About
Community
Bad Ideas
Drugs
Ego
Erotica
Fringe
Society
Technology
Hack
Phreak
Broadcast Technology
Computer Technology
Cryptography
Science & Technology
Space, Astronomy, NASA
Telecommunications
The Internet: Technology of Freedom
Viruses
register | bbs | search | rss | faq | about
meet up | add to del.icio.us | digg it

A Primer on Embedded Controllers and Microcontrollers

2) EMBEDDED CONTROLLERS AND MICROCONTROLLERS

2.1) What is a Microcontroller?

A controller is used to control (makes sense!) some process or aspect of the environment. A typical microcontroller application is the monitoring of my house. As the temperature rises, the controller causes the windows to open. If the temperature goes above a certain threshold, the air conditioner is activated. If the system detects my mother-in-law approaching, the doors are locked and the windows barred. In addition, upon detecting that my computer is turned on, the stereo turns on at a deafening volume (for more on this, see the section on development tools).

At one time, controllers were built exclusively from logic components, and were usually large, heavy boxes (before this, they were even bigger, more complex analog monstrosities). Later on, microprocessors were used and the entire controller could fit on a small circuit board. This is still common - you can find many [good] controllers powered by one of the many common microprocessors (including Zilog Z80, Intel 8088, Motorola 6809, and others).

As the process of miniaturization continued, all of the components needed for a controller were built right onto one chip. A one chip computer, or microcontroller was born. A microcontroller is a highly integrated chip which includes, on one chip, all or most of the parts needed for a controller. The microcontroller could be called a "one-chip solution". It typically includes: CPU (central processing unit) RAM (Random Access Memory) EPROM/PROM/ROM (Erasable Programmable Read Only Memory) I/O (input/output) - serial and parallel timers interrupt controller

By only including the features specific to the task (control), cost is relatively low. A typical microcontroller has bit manipulation instructions, easy and direct access to I/O (input/output), and quick and efficient interrupt processing. Microcontrollers are a "one-chip solution" which drastically reduces parts count and design costs.

2.2) What is an Embedded Controller?

Hah! Why not ask an easy question like "why is there hate in the world?" or "how does the brain work"?

Simply (and naively stated) an embedded controller is a controller that is embedded in a greater system. Great, we hit that nail right on the head. A rigid definition is difficult if not impossible to formulate, since the usual result is something like "most embedded controllers are...". The problem here is "most". We can't seem to shake that word from the definition. No matter how clever you feel your definition is, some wiseguy will come along and find an exception, or two, or 50.

You COULD say that an embedded controller is a controller (or computer) that is embedded into some device for some purpose other than to provide general purpose computing. Of course, someone will eventually prove you wrong, but who cares?

A common example of a general purpose computer, would be a typical PC clone. The x86 processor in this machine can't really be considered an embedded processor, since the machine is typically used for general purpose computing. However, what is general purpose computing? Take this same PC clone, turn it into a multi-media machine, and voila! You have an appliance - much on the order of a microwave oven or television. Is the x86 processor now considered an embedded processor? Or, is the PC clone itself, now considered an embedded controller, controlling the multi-media peripherals? Hey - I'm getting to old for this nonsense.

One common misconception is that an embedded controller is the same as a microcontroller. How about all of those 68000s, 32032s, x86s, Z80s, and so on that are used as embedded controllers. They aren't microcontrollers. Or are they? What's the difference between an embedded controller and a microcontroller? Well, today - not much. I wouldn't touch that question with a ten foot logic probe.

We might be safe by stating that an embedded controller controls something (for example controlling a device such as a microwave oven, car braking system, or a cruise missile). Is this always true? How about an embedded processor? You know, it just doesn't end.

The main thing is not to get to hung up on precise definitions. Black and white? Hell no, we've got grey scale, dithering, diffusion, you name it! Same thing goes here embedded controllers, just go with the flow. It all depends on your point of view.

2.3) Applications

In addition to control applications such as the above home monitoring system, microcontrollers are frequently found in embedded applications (embedded controllers?). Among the many uses that you can find one or more microcontrollers: appliances (microwave oven, refrigerators, television and VCRs, stereos), automobiles (engine control, diagnostics, climate control), environmental control (greenhouse, factory, home), instrumentation, aerospace, and thousands of other uses.

Microcontrollers are used extensively in robotics. In this application, many specific tasks might be distributed among a large number of microcontrollers in one system. Communications between each microcontroller and a central, more powerful microcontroller (or microcomputer, or even large computer) would enable information to be processed by the central computer, or to be passed around to other microcontrollers in the system.

A special application that microcontrollers are well suited for is data logging. Stick one of these chips out in the middle of a corn field or up in a ballon, and monitor and record environmental parameters (temperature, humidity, rain, etc). Small size, low power consumption, and flexibility make these devices ideal for unattended data monitoring and recording.

2.4) Flavors

Microcontrollers come in many flavors and varieties. Depending on the power and features that are needed, you might choose a 4 bit, 8 bit, 16 bit, or 32 bit microcontroller. In addition, some specialized versions are available which include features specific for communications, keyboard handling, signal processing, video processing, and other tasks.

3) THE MICROCONTROLLER MARKET

Thanks to Robin Getz of National Semiconductor for supplying much of the material in this section.

3.1) Shipments

WorldWide Microcontroller Shipments (in millions of dollars)

'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 4-bit 1,393 1,597 1,596 1,698 1,761 1,826 1,849 1,881 1,856 1,816 1,757 8-bit 2,077 2,615 2,862 3,703 4,689 5,634 6,553 7,529 8,423 9,219 9,715 16-bit 192 303 340 484 810 1,170 1,628 2,191 2,969 3,678 4,405

WorldWide Microcontroller Shipments (in Millions)

'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 4-bit 778 906 979 1036 1063 1110 1100 1096 1064 1025 970 8-bit 588 753 843 1073 1449 1803 2123 2374 2556 2681 2700 16-bit 22 38 45 59 106 157 227 313 419 501 585

Source: WSTS & ICE - 1994

If you were wondering why you should bother learning about microcontrollers - well, the tables above should fairly scream the answer at you. Microcontrollers will be *BIG* business - we're talking piles of cash - billions!

Notice that even the lowly 4-bit device is holding its own - what use is a 16-bit part in a toaster oven? Also notice that the 8-bit market just keeps growing, and will probably continue to grow. 8-bit devices account for over half of the market, and will eventually grab even more. Now do you understand why every silicon manufacturer is really pushing their 8-bit microcontrollers?

3.2) Industrial applications

Average Semiconductor Content per Passenger Automobile (in Dollars)

'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00 $ 595 634 712 905 1,068 1,237 1,339 1,410 1,574 1,852 2,126

Source: ICE - 1994

The automotive market is the most important single driving force in the microcontroller market, especially at it's high end. Several microcontroller families were developed specifically for automotive applications and were subsequently modified to serve other embedded applications.

The automotive market is demanding. Electronics must operate under extreme temperatures and be able to withstand vibration, shock, and EMI. The electronics must be reliable, because a failure that causes an accident can (and does) result in multi-million dollar lawsuits. Reliability standards are high - but because these electronics also compete in the consumer market - they have a low price tag.

Automotive is not the only market that is growing. DataQuest says that in the average North American's home there are 35 microcontrollers. By the year 2000 - that number will grow to 240. Consumer electronics is a booming business.

3.3) Deciding whose microcontroller to use

When deciding which devices to implement in a design, there are lots of things to consider besides who else is using these devices (and how many are they using). - Can I expect help when I am having problems? - What development tools are available and how much do they cost? - What sort of documentation is available (reference manuals, application notes, books)? - Can I work a deal by purchasing more devices at one manufacturer? That is, purchasing not only the microcontroller, but also peripherals (A/D, memory, voltage regulator, etc.) from one company). - Do they support OTPs, windowed devices, mask parts?

3.4) The players

Here is a list of the big guys. Keep in mind that units does not equal dollars. Since some companies deal primarily in higher end devices, they need to sell fewer units to achieve a higher dollar total.

Company Units (k) 1993 ----------------------------------------------- Motorola 358,894 Mitsubishi 71,674 NEC 70,180 Hitachi 67,873 Philips 56,680 Intel 46,876 SGS-Thomson 37,350 Microchip 35,477 Matsushitta 34,200 Toshiba 32,205 National Semiconductor 31,634 Zilog 31,000 Texas Instruments 29,725 Siemens 20,874 Sharp 17,505

SOURCE: DataQuest June 1994

The above numbers are just somebody's best guess - believe them if you want to. Since they get paid to come up with these numbers, one would hope that they would be fairly reliable. However, one of these numbers is wrong for certain (and Robin Getz won't say whether it should be higher or lower ;-).

4) MICROCONTROLLER FEATURES

Thanks to Robin Getz of National Semiconductor who supplied some of the material in this section.

4.1) Fabrication techniques

CMOS - Complementary Metal Oxide Semiconductor

This is the name of a common technique used to fabricate most (if not all) of the newer microcontrollers. CMOS requires much less power than older fabrication techniques, which permits battery operation. CMOS chips also can be fully or near fully static, which means that the clock can be slowed up (or even stopped) putting the chip in sleep mode. CMOS has a much higher immunity to noise (power fluctuations or spikes) than the older fabrication techniques.

PMP - Post Metal Programming (National Semiconductor)

PMP is a high-energy implantation process that allows microcontroller ROM to be programmed AFTER final metalization. Usually ROM is implemented in the second layer die, with nine or ten other layers then added on top. That means the ROM pattern must be specified early in the production process, and completed prototypes devices won't be available typically for six to eight weeks. With PMP, however, dies can be fully manufactured through metalization and electrical tests (only the passivation layers need to be added), and held in inventory. This means that ROM can be programmed late in production cycle, making prototypes available in only two weeks.

4.2) Architectural features

Von-Neuman Architecure

Microcontrollers based on the Von-Neuman architecture have a single "data" bus that is used to fetch both instructions and data. Program instructions and data are stored in a common main memory. When such a controller addresses main memory, it first fetches an instruction, and then it fetches the data to support the instruction. The two separate fetches slows up the controller's operation.

Harvard Architecture

Microcontrollers based on the Harvard Architecture have separate data bus and an instruction bus. This allows execution to occur in parallel. As an instruction is being "pre-fetched", the current instruction is executing on the data bus. Once the current instruction is complete, the next instruction is ready to go. This pre-fetch theoretically allows for much faster execution than a Von-Neuman architecture, but there is some added silicon complexity.

CISC

Almost all of today's microcontrollers are based on the CISC (Complex Instruction Set Computer) concept. The typical CISC microcontroller has well over 80 instructions, many of them very powerful and very specialized for specific control tasks. It is quite common for the instructions to all behave quite differently. Some might only operate on certain address spaces or registers, and others might only recognize certain addressing modes.

The advantages of the CISC architecture is that many of the instructions are macro-like, allowing the programmer to use one instruction in place of many simpler instructions.

RISC

The industry trend for microprocessor design is for Reduced Instruction Set Computers (RISC) designs. This is beginning to spill over into the microntroller market. By implementing fewer instructions, the chip designed is able to dedicate some of the precious silicon real-estate for performance enhancing features. The benefits of RISC design simplicity are a smaller chip, smaller pin count, and very low power consumption.

Among some of the typical features of a RISC processor: - Harvard architecture (separate buses for instructions and data) allows simultaneous access of program and data, and overlapping of some operations for increased processing performance - Instruction pipelining increases execution speed - Orthogonal (symmetrical) instruction set for programming simplicity; allows each instruction to operate on any register or use any addressing mode; instructions have no special combinations, exceptions, restrictions, or side effects

SISC

Actually, a microcontroller is by definition a Reduced Instruction Set Computer (at least in my opinion). It could really be called a Specific Instruction Set Computer (SISC). The [original] idea behind the microcontroller was to limit the capabilities of the CPU itself, allowing a complete computer (memory, I/O, interrupts, etc) to fit on the available real estate. At the expense of the more general purpose instructions that make the standard microprocessors (8088, 68000, 32032) so easy to use, the instruction set was designed for the specific purpose of control (powerful bit manipulation, easy and efficient I/O, and so on).

Microcontrollers now come with a mind boggling array of features that aid the control engineer - watchdog timers, sleep/wakeup modes, power management, powerful I/O channels, and so on. By keeping the instruction set specific (and reduced), and thus saving valuable real estate, more and more of these features can be added, while maintaining the economy of the microcontroller.

4.3) Advanced Memory options

EEPROM - Electrically Erasable Programmable Read Only Memory

Many microcontrollers have limited amounts of EEPROM on the chip. EEPROM seems more suited (becuase of its economics) for small amounts of memory that hold a limited number of parameters that may have to be changed from time to time. This type of memory is relatively slow, and the number of erase/write cycles allowed in its lifetime is limited.

FLASH (EPROM)

Flash provides a good better solution than regular EEPROM when there is a requirement for large amounts of non-volatile program memory. It is both faster and permits more erase/write cycles than EEPROM.

Battery backed-up static RAM

Battery backed-up static RAM is useful when a large non-volatile program and DATA space is required. A major advantage of static RAM is that it is much faster than other types of non-volatile memory so it is well suited for high performance application. There also are no limits as to the number of times that it may be written to so it is perfect for applications that keep and manipulate large amounts of data locally.

Field programming/reprogramming

Using nonvolatile memory as a place to store program memory allows the device to be reprogrammed in the field without removing the microcontroller from the system that it controls. One such application is in automotive engine controllers. Reprogrammable non-volatile program memory on the engine's microcontroller allows the engine controller program to be modified during routine service to incorporate the latest features or to compensate for such factors as engine aging and changing emissions control laws (or even to fix bugs!!). Reprogramming of the microcontroller could become a standard part the routine engine tune-up.

Almost every application could benefit from this type of program memory - If a modem's hardware supported it, you could remotely upgrade your modem from Vfast to V.34, or incorporate new features such as voice control or a digital answering machine.

OTP - One Time Programmable

An OTP is a PROM (Programmable Read-Only-Memory) device. Once your program is written into the device with a standard EPROM programmer, it can not be erased or modified. This is usually used for limited production runs before a ROM mask is done in order to test code.

A OTP (One Time Programmable) part uses standard EPROM, but the package has no window for erasing. Once your program is written into the device with a standard EPROM programmer, it cannot be erased or modified. (Well, sort of - any bit that is a one can be changed to a zero - but a bit that is a zero cannot be changed into a one).

As product design cycles get shorter, it is more important for micro manufacturers to offer OTPs as an option. This was commonly used for limited production runs before a ROM mask in order to test code. However, one problem with Mask ROM is that programming, setup, and engineering charges make it economical only when the systems manufacturer purchases large quantities of identically programmed micros. Then when you discover THAT bug (and find it and fix your code), you have quantities of *old buggy* micros around that you have to throw away. Not to mention that lead time (the time when you submit your code to the micro manufacture, to the time you receive your micro with your code on it) can be at least 8 weeks, and as bad as 44 weeks.

Software protection

Either by encryption or fuse protection, the programmed software is protected against unauthorized snooping (reverse engineering, modifications, piracy, etc.).

This is only an option on OTPs and Windowed devices. On Masked ROM devices, security is not needed - the only way to read your code would be to rip the microcontroller apart with a scanning electron microscope - and how many people really have one of those?

Although - and this is a manufacturer's little know fact - when a silicon manufacturer makes your ROMed microcontroller - they have to test it in order to make sure that it is programmed properly. (You should see what a spec of dust does on a mask :-) In order to test this, they must be able to read out the ROM and compare it to the code you submitted. This mode is known as test mode. IN TEST MODE YOU CAN READ OUT THE ROM OF ANY DEVICE. Anybody who tells you different, does not know what they are talking about - or is lying. This is usually not a big deal because test mode is ***VERY*** confidential, and (usually) only known by that manufacturer (i.e. you cannot put a device into test mode by accident). Test mode is ONLY applicable with ROMed devices.

4.4) Power Management and Low Voltage

Low voltage parts

Since automotive applications have been the driving force behind most microcontrollers, and 5 Volts is very easy to do in a car, most microcontrollers have only supported 4.5 - 5.5 V operation. In the recent past, as consumer goods are beginning to drive major segments of the microcontroller market, and as consumer goods become portable and lightweight, the requirement for 3 volt (and lower) microcontrollers has become urgent (3 volts = 2 battery solution / lower voltage = longer battery life). Most low voltage parts in the market today are simply 5 volt parts that were modified to operate at 3 volts (usually at a performance loss). Some micros being released now are designed from the ground up to operate properly at 3.0 (and lower) voltages, which offer comparable performance of the 5 volt devices.

Now, why are voltages REALLY going down on ICs? Paul K. Johnson (of Hewlett-Packard) explains:

There are a few interesting rules of thumb regarding transistors: 1) The amount of power they dissipate is proportional to their size. If you make a transistor half as big, it dissipates half as much power. 2) Their propagation delay is proportional to their size. If you make a transistor half as big, it's twice as fast. 3) Their cost is proportional to the square of their size. If you make them half as big, they cost one quarter as much.

If you make a transistor smaller, you improve the power, speed, and cost. The only drawback is that they are harder to make. (Well, how hard can it be for HP, IBM, Motorola, National, etc?) Everybody in the world wants to make transistors smaller and smaller, the advantages are enormous.

For years people have been using 5 Volts to power IC's. Because the transistors were large, there was little danger damaging the transistor putting this voltage across it. However, now that the transistors are getting so small, 5 Volts will actually fry them. The only way around this is to start lowering the voltage. This is why people are now using 3 (actually 3.3) Volt logic, and lower in the next few years. It isn't just because of batteries.

Brownout Protection

Brownout protection is usually an on-board protection circuit that resets the device when the operating voltage (Vcc) is lower than the brownout voltage. The device is held in reset and will remain in reset when Vcc stays below the Brownout voltage. The device will resume execution (from reset) after Vcc has risen above the brownout Voltage.

Idle/Halt/Wakeup

The device can be placed into IDLE/HALT mode by software control. In both Halt and Idle conditions the state of the microcontroller remains. RAM is not cleared and any outputs are not changed. The terms idle and halt often have different definitions, depending on the manufacturer. What some call idle, others may call halt, and vice versa. It can be confusing, so check the data sheet for the device in question to be sure.

In IDLE mode, all activities are stopped except: - associated on-board oscillator circuitry - watchdog logic (if any) - the clock monitor - the idle timer (a free running timer) Power supply requirements on the microcontroller in this mode are typically around 30% of normal power requirements of the microprocessor. Idle mode is exited by a reset, or some other stimulus (such as timer interrupt, serial port, etc.). A special timer/counter (the idle timer) causes the chip to wake up at a regular interval to check if things are OK. The chip then goes back to sleep.

IDLE mode is extremely useful for remote, unattended data logging - the microprocessor wakes up at regular intervals, takes its measurements, logs the data, and then goes back to sleep.

In Halt mode, all activities are stopped (including timers and counters). The only way to wake up is by a reset or device interrupt (such as an I/O port). The power requirements of the device are minimal and the applied voltage (Vcc) can sometimes be decreased below operating voltage without altering the state (RAM/Outputs) of the device. Current consumption is typically less than 1 uA.

A common application of HALT mode is in laptop keyboards. In order to have maximum power saving, the controller is in halt until it detects a keystroke (via a device interrupt). It then wakes up, decodes and sends the keystroke to the host, and then goes back into halt mode, waiting either for another keystroke, or information from the host.

Multi-Input Wakeup (National Semiconductor)

The Multi-Input WakeUp (MIWU) feature is used to return (wakeup) the microcontroller from either HALT or IDLE modes. Alternately MIWU may also be used to generate up to 8 edge selectible external interrupts. The user can select whether the trigger condition on the pins is going to be either a positive edge (low to high) or a negative edge (high to low).

4.5) I/O

UART

A UART (Universal Asynchronous Receiver Transmitter) is a serial port adapter for asynchronous serial communications.

USART

A USART (Universal Synchronous/Asynchronous Receiver Transmitter) is a serial port adapter for either asynchronous or synchronous serial communications. Communications using a USART are typically much faster (as much as 16 times) than with a UART.

Synchronous serial port

A synchronous serial port doesn't require start/stop bits and can operate at much higher clock rates than an asynchronous serial port. Used to communicate with high speed devices such as memory servers, display drivers, additional A/D ports, etc. Can also be used to implement a simple microcontroller network.

SPI (Motorola)

An SPI (serial peripheral interface) is a synchronous serial port.

SCI

An SCI (serial communications interface) is an enhanced UART (asynchronous serial port).

I2C bus - Inter-Integrated Circuit bus (Philips)

The I2C bus is a simple 2 wire serial interface developed by Philips. It was developed for 8 bit applications and is widely used in consumer electronics, automotive and industrial applications. In addition to microcontrollers, several peripherals also exist that support the I2C bus.

The I2C bus is a two line, multi-master, multi-slave network interface with collision detection. Up to 128 devices can exist on the network and they can be spread out over 10 meters. Each node (microcontroller or peripheral) may initiate a message, and then transmit or receive data. The two lines of the network consist of the serial data line and the serial clock line. Each node on the network has a unique address which accompanies any message passed between nodes. Since only 2 wires are needed, it is easy to interconnect a number of devices.

MICROWIRE/PLUS (National Semiconductor)

MICROWIRE/PLUS is a serial synchronous bi-directional communications interface. This is used on National Semiconductor Corporation's devices (microcontrollers, A/D converters, display drivers, EEPROMS, etc.).

CAN & J1850

CAN (Controller Area Network) is a mutiplexed wiring scheme that was developed jointly by Bosh and Intel for wiring in automobiles. J1850 is the SAE (Society of Automotive Engineers) multiplexed automotive wiring standard that is currently in use in North America.

Both of these groups have the "NOT INVENTED HERE" syndrome and refuse to work with each other's standard. The standards are quite different and are not compatible at all.

The CAN specification seems to be the one that is being used in industrial control both in North American and Europe. With lower cost microcontrollers that support CAN, CAN has a good potential to take off.

Analog to Digital Conversion (A/D)

Converts an external analog signal (typically relative to voltage) and converts it to a digital representation. Microcontrollers that have this feature can be used for instrumention, environmental data logging, or any application that lives in an analog world.

The various types of A/D converters that can be found:

Succesive Approximation A/D converters -- This the most common type of A/D and is used in the majority of microcontrollers. In this technique, the converter figures out each bit at a time (most significant first) and finds if the next step is higher or lower. This way has some benefits - it takes exactly the same amount of time for any conversion - it is very common - (and therefore very cheap). However it also has some disadvantages - it is slow - for every bit it takes at least one clock cycle - the best an 8-bit A/D can do is at least 8 clock cycles (and a couple for housekeeping). Because it takes so long - it is a power hog as compared to the other types of A/Ds.

Single Slope A/D converters -- This is the type of converter that you can build yourself (if the microcontroller has a couple of analog blocks on it). Your single slope A/D converter would include Analog Mux / comparator / timer (8-bit timer = 8 bit A/D - 16-bit timer = 16 bit A/D) with input capture and a constant current source. The only microcontroller (that I know of) that has all of this on it is National's COP888EK.

First Step is to clear the timer to 0000 and then start it. It is a simple matter to hang an external capacitor, and charge it with the constant current source (linearly because of the current source) when the voltage on the cap exceeds the sampling voltage, the comparitor toggles, stops the timer - and voila - you have the voltage in uSecs - with 16-bit accuracy. The only drawback is you can't really expect 16 bits (14 yes) - the conversion time varies quite a bit, and it is SLOW.

Delta-Sigma A/Ds converters -- This type of A/D converter is found on higher-end DSPs. These are the hardest to understand of the A/Ds because it just makes a best guess (a little National Semiconductor humor here :-). Delta sigma A/Ds can be broken down into two main parts.

The modulator which does the A/D conversion and the filter, which turns the output of the modulator into a format suitible for the microcontroller (or DSP).

The modulator is very simple - it just compares the input voltage to the average of the last 100 (or so) modulator outputs and decides if the input is higher or lower than the average. This happens millions of times a second, resulting in a high speed single-bit datastream of 1s and 0s who's *average* is equal to the input voltage. Becuse the ouput is only a one or a zero, there are very few sources of errors. This is the main reason that delta-sigma A/Ds are **very** accurate.

The filter comes after the modulator ... and this filter is essentially a big DSP block. It must take the very high speed stream of ones and zeros and turn it into a slower speed stream of 16-bit (or greater) words to be used by the microcontroller. This process is called decimation and the filter is often called a "comb filter". Another digital filter follows this stage and rejects unwanted frequencies. This filter performs a similar function to the anti-aliasing filter required in many traditional A/D appliactions, but it does it at an unprecedented level of performance and at low cost. This is the other major benefit of delta-sigma A/Ds.

Flash A/D -- This is the basic architecure for the fastest category of A/Ds. The flash converter involves looking at each level that is possible and instantaneously saying what level the voltage is at. This is done by setting up comparators as threshold detectors with each detector being set up for a voltage exaclty 1 LSB higher than the detector below it. The benefit of this architecture is that with a single clock cycle, you can tell exactly what the input voltage is - that is why it is so fast. The disadvantage is that to achieve 8-bit accuracy you need 256 comparators and to achieve 10-bit accuracy you need 1024 comparators. To make these comparators operate at higher speeds, they have to draw LOTS of current, and beyond 10 bits, the number of comparators required becomes totally unmanageable.

D/A (Digital to Analog) Converters

This feature takes a Digital number and converts it to a analog output. The number 50 would be changed to the analog output of (50/256 * 5Volts) = .9765625V on a 8-bit / 5 Volt system.

Pulse width modulator

Often used as a digital-to-analog conversion technique. A pulse train is generated and regulated with a low-pass filter to generate a voltage proportional to the duty cycle.

Pulse accumulator

A pulse accumulator is an event counter. Each pulse increments the pulse accumulator register, recording the number of times this event has occurred.

Input Capture

Input Capture can measure external frequencies or time intervals by copying the value from a free running timer into a register when an external event occurs.

Comparator

One or more standard comparators can sometimes be placed on a microcontroller die. These comparators operate much like standard comparators however the input and output signals are available on the microcontroller bus.

Mixed (Analog-Digital) Signal

We live in an analog world where the information we see, hear, process, and exchange with each other, and with our mechanical and electronic systems, is always an analog quantity - pressure, temperature, voltage, current, air and water flow are always analog entities. They can be digitized for more efficient sorting, storage and transmittal, but the interface - the input and output - is almost always analog. Thus the essence of analog electronics lies in sensing continuously varying information, shaping and converting it for the efficiency of digital processing and transmission, and reshaping the digital data to an analog signal at the other end.

Mixed analog-digital devices are being used increasingly to integrate the complex functions of high-speed telecommunications, or the real-time data processing demanded by industrial control systems and automotive systems. Start looking for microcontrollers that have analog comparators, analog multiplexers, current sources, voltage doublers, PLL (Phase Lock Loops) and all sorts of peripherals that you thought were analog only.

4.6) Interrupts

Polling

Polling is not really a "feature" - it's what you have to do if your microcontroller of choice does not have interrupts. Polling is a software technique whereby the controller continually asks a peripheral if it needs servicing. The peripheral sets a flag when it has data ready for transferring to the controller, which the controller notices on its next poll. Several such peripherals can be polled in succession, with the controller jumping to different software routines, depending on which flags have been set.

Interrupts

Rather than have the microcontroller continually polling - that is, asking peripherals (timers / UARTS / A/Ds / external components) whether they have any data available (and finding most of the time they do not), a more efficient method is to have the peripherals tell the controller when they have data ready. The controller can be carrying out its normal function, only responding to peripherals when there is data to respond to. On receipt of an interrupt, the controller suspends its current operation, identifies the interrupting peripheral, then jumps (vectors) to the appropriate interrupt service routine.

The advantage of interrupts, compared with polling, is the speed of response to external events and reduced software overhead (of continually asking peripherals if they have any data ready).

Most microcontrollers have at least one external interrupt, which can be edge selectible (rising or falling) or level triggered. Both systems (edge/level) have advantages. Edge - is not time sensitive, but it is susceptible to gitches. Level - must be held high (or low) for a specific duration (which can be a pain - but is not susceptible to glitches).

Interrupts are critical when you are controlling anything (this is what microcontrollers do). If you misunderstand any of the terms, and design your systems with the way you *think* it works - not the way it *really* works - it will effect system performance. It may also work for a very long time with no problems, and then all of a sudden fail. Check your datasheets - these descriptions are the correct ones (or are at least supposed to be), but that does not mean that they are agreed to by the silicon manufacturers, (or by the marketing guys that they employ, and who write parts of the data sheets.)

4 bit microcontrollers usually have either a polling or non-vectored type of interrupt scheme. 8 and 16 bit microcontrollers usually have some type of vectored arbitration type of interrupt scheme. 32 bit microcontrollers usually will have some type of vectored priority type of interrupt scheme. Again, check your data sheet to make sure - or ask a manufacturer's rep if you aren't sure.

Maskable Interrupts

A maskable interrupt is one that you can disable or enable (masking it out means disabling the interrupt), whereas non-maskable interrupts you can't disable. The benefit of maskable interrupts is that you can turn off a particular interrupts (for example a UART) during some time critical task. Then, those particular interrupts will be ignored thus allowing the microcontroller to deal with the task at hand. Most microcontrollers (as well as most microprocessors) have some type of Global Interrupt Enable (GIE) which allows you to turn off (or on) all of the maskable interrupts with one bit. NOTE: GIE usually does not effect any NMI (Non-Maskable Interrupts)

Vectored Interrupts

Simple (non-vectored) interrupts is one of the simplest interrupt schemes there is (Simple = less silicon = more software = slower). Whenever there is an interrupt, the program counter (PC) branches to one specific address. At this address, the system designer needs to check the interrupts (one at a time) to see which peripheral has caused the interrupt to occur. Code for this may look like (on a COP8):

IFBIT UART,PSW ; If the UART bit has been set JP UART_Recieve ; Jump to the UART receive service routine

IFBIT T1,PSW ; If the timer has underflowed JP Underflow ; Jump to the underflow service routine

... and so on

This can be *very* slow - and the time between the interrupt happening and the time the service routine is entered, depends on how the system designer sets up their ranking. The peripheral that is checked last takes the longest to process. Most microcontrollers that have fewer than 3 - 5 interrupts use this method. The benefit of this is that the system designer can set the priority - The most important peripheral gets checked first - and you get to decide which peripheral that is.

Vectored interrupts are a little easier to set up, but the system designer has less control of the system (i.e. is dependent on the silicon manufacture to make the proper decisions during design of the chip). When an interrupt occurs, the hardware interrupt handler automatically branches to a specific address depending on what interrupt occurred. This is much faster than the non-vectored approach described above, however the system designer does not get to decide what peripheral gets checked first. Example (on a National Semiconductor COP888CG):

Rank Source Description Vector Address ------------------------------------------------------------------ 1 (highest) Software INTR Instruction 01FE - 01FF 2 External Pin G0 Edge 01FA - 01FB 3 Timer T0 Underflow 01F8 - 01F9 4 Timer T1 T1A / Underflow 01F6 - 01F7 5 Timer T1 T1B 01F4 - 01F5 6 MICROWIRE/PLUS BUSY Goes Low 01F2 - 01F3 7 UART Receive 01EE - 01EF 8 UART Transmit 01EC - 01ED 9 Timer T2 T2A / Underflow 01EA - 01EB 10 Timer T2 T2B 01E8 - 01E9 11 Timer T3 T3A / Underflow 01E6 - 01E7 12 Timer T3 T3B 01E4 - 01E5 13 Port L / MIWU Port L Edge 01E2 - 01E3 14 (lowest) Default VIS Interaction 01E0 - 01E1

In ROM location 01F8 - 01F9 (2bytes x 8 bits = 16bit address) the system designer enters the ROM location of where they want the service routine (of the Timer T0 underflow) to be. And so on for the rest of the addresses.

Interrupt arbitration and priority

Interrupt arbitration and priority - These are two of the most misused words when it comes to microcontrollers (microprocessors too for that matter) and it's generally because no one knows the difference between them. Priority is not Arbitration. Arbitration is not Priority. Lets see if we can sort out the differences.

Arbitration - If you look at the above chart of the COP888CG, you may think the interrupts are prioritized because they have some ranking. They do have rank, but they are not prioritized. What happens is that (in an arbitration scheme) when an interrupt occurs, the GIE (Global Interrupt Enable) is cleared. This effectively means that all future interrupts will be delayed until the GIE is set. The GIE becomes set only if the system designer sets it in a service routines, or on a RETI (Return from Interrupt).

Quick Example 1 - Timer 1 underflows - the hardware clears the GIE, looks at ROM locations 01F6 and 01F7 and jumps to the ROM location pointed to by those addresses. The program does a couple things, and then sets the GIE (because the user wants to recognize an external interrupt during this service routine). However while in the service routine, Timer 3 underflows. Although a timer 3 underflow is lower in rank than a timer 1 underflow, the interrupt handler does not care - it simply looks at the GIE, and because it is set - handles the interrupt (now we have nested interrupts). The Timer 1 underflow service routine will not be completed until the Timer 3 underflow is complete.

Quick Example 2 - Timer 3 underflows at the same time as an External interrupt occur. The one to be handled first is the External Interrupt. If the user sets the GIE, the interrupt handler will jump down to the Timer 3 underflow handler. If the user does not set the GIE, the microcontroller handles the External interrupt, does a RETI, and the Timer 3 underflow can now be handled.

Priority - In a priority scheme, things are prioritized (well, what'd you expect?). If Timer T0 underflows, the only thing that can interrupt that is an external or software interrupt. If a external or software interrupt occurs, the interrupt handler will branch to these service routines. When they are complete, it will return to the Timer T0 underflow.

Quick Example - In the below timing diagram, the following happens: 1) Timer T0 underflows 2) Timer T2 underflows 3) An External Interrupt occurs.

In a priority scheme, the following would happen:

External Interrupt |---------| | | Timer T0 Underflow |-------| |------| | | Timer T2 Underflow | |------| | | Normal Execution ---| |-------

^ ^ ^ ^ ^ ^ | | | | | | Time -> | | | | | \-T2 Done | | | | \-------- T0 Done | | | \-------------- Ext Done | | \------------------------ Ext Edge | \----------------------- T2 Underflows \--------------------------- T0 Underflows

This is what RTOS (Real Timer Operating Systems) do - prioritize and handle interrupts.

4.7) Special microcontroller features

Watchdog timer

A watchdog timer provides a means of graceful recovery from a system problem. This could be a program that goes into an endless loop, or a hardware problem that prevents the program from operating correctly. If the program fails to reset the watchdog at some predetermined interval, a hardware reset will be initiated. The bug may still exist, but at least the system has a way to recover. This is especially useful for unattended systems.

Digital Signal Processors (DSP)

Microcontrollers react to and control events - DSPs execute repetitive math-intensive algorithms. Today many embedded applications require both types of processors, and semiconductor manufacturers have responded by introducing microcontrollers with on-chip DSP capability and DSPs with on-chip microcontrollers.

The most basic thing a DSP will do is a MACC (Multiply and ACCumulate). The number of data bits a DSP can Multiply and ACCumulate will determine the dynamic range (and therefore the application).

Bits Fixed/Floating Dynamic Range Typical Application

8 Fixed 48 dB Telephone-quality voice 16 Fixed 96 dB Compact disk (marginal) 24 Fixed 144 dB Compact disk (room for error)

Clock Monitor

A clock monitor can shut the microcontroller down (by holding the microcontroller in reset) if the input clock is too slow. This can usually be turned on or off under software control.

Resident program loader

Loads a program by Initializing program/data memory from either a serial or parallel port. Convenient for prototyping or trying out new features, eliminates the erase/burn/program cycle typical with EPROMs, and allows convenient updating of a system even from an offsite location.

Monitor

A monitor is a program installed in the microcontroller which provides basic development and debug capabilities. Typical capabilities of a microcontroller monitor include: loading object files into system RAM, executing programs, examining and modifying memory and registers, code disassembly, setting breakpoints, and single-stepping through code. Some simple monitors only allow basic functions such as memory inspection, and the more sophisticated monitors are capable of a full range of debug functions.

Monitors can either communicate with a dumb terminal or with a host computer such as a PC. Much of the work of the monitor (such as user interface) can be offloaded to the host PC running a program designed to work with the monitor. This makes it possible to reduce the size and complexity of the code that must be installed in the target system.

MIL transducer

An MIL transducer is a sophisticated and expensive device that detects the presence of your mother-in-law. Sensitivity settings are possible for a full range of stimuli such as: snarling, stomping, nasty faces, and others. Techno-Wimp (address withheld upon request), the sole manufacturer of the MIL transducer, has recently announced a major new version which is sensitive enough to detect less-tangible stimuli. This breakthrough product is dubbed the MIL-WOMF ("Whoa, outta my face!") transducer. Both the original MIL and the new MIL-WOMF transducers are programmable and easy to interface to most microcontrollers.

5) Some popular microcontrollers

Some common microcontrollers are described below. A common question is "what microcontroller should I use for...?" Well, that's a tough one. The best advice would be to choose a chip that has a full set of development tools at the price you can afford, and good documentation. For the hobbyist, the Intel 8051, Motorola 68hc11, or Microchip PIC would all make suitable choices.

8048 (Intel)

The grandaddy of 'em all, the first microcontroller, it all started here! Although a bit long in the tooth and a bit kludgey in design (at least by today's standards), it is still very popular due to its very low cost, availability, and wide range of development tools.

Modified Harvard architecture with program ROM on chip with an additional 64 to 256 bytes of RAM also on chip. I/O is mapped in its own space.

8051 (Intel and others)

The 8051, Intel's second generation of microcontrollers, rules the microcontroller market at the present time. Although featuring a somewhat bizarre design, it is a very powerful and easy to program chip (once you get used to it).

Modified Harvard architecture with separate address spaces for program memory and data memory. The program memory can be up to 64K. The lower portion (4K or 8K depending on type) may reside on chip. The 8051 can address up to 64K of external data memory, and is accessed only by indirect addressing. The 8051 has 128 bytes (256 bytes for the 8052) of on-chip RAM, plus a number of special function registers (SFRs). I/O is mapped in its own space.

The 8051 features the so-called "boolean processor". This refers to the way instructions can single out bits just about anywhere (RAM, accumulators, I/O registers, etc.), perform complex bit tests and comparisons, and then execute relative jumps based on the results.

Piles of software, both commercial and free, are available for the 8051 line. Many manufacturers supply what must be a hundred different variants of this chip for any requirement. Often featured in construction projects in the popular hobbyist magazines.

80c196 (MCS-96)

The third generation of Intel microprocessors, the 80c196 is a 16 bit processor. Originally fabricated in NMOS (8096), it is now mainly available in CMOS. Intel Corp. has recently introduced a clock-doubled (50MHz) version of the 80c196.

Among the many features it includes are: hardware multiply and divide, 6 addressing modes, high speed I/O, A/D, serial communications channel, up to 40 I/O ports, 8 source priority interrupt controller, PWM generator, and watchdog timer.

80186,80188 (Intel)

These chips are, in essence, microcontroller versions of the 8086 and 8088 (of IBM/PC fame). Included on the chip are: 2 channels of DMA, 2 counter/timers, programmable interrupt controller, and dynamic RAM refresh. There are several variations including: low power versions, variations with serial ports, and so on.

One major advantage you gain by using one of these parts is that you can use standard PC development tools (compilers, assemblers, etc) for developing you applications. If you are already familiar with PC software development, the learning curve will be short, since these chips have the same basic architecture as the original 8088 (as used in the IBM/PC).

Other advantages include high speed processing, a full megabyte addressing space, and powerful interrupt processing.

80386 EX (Intel)

The 80386 EX is of course a 386 in microcontroller clothing. Included on the chip are: serial I/O, power management, DMA, counter/timers, programmable interrupt controller, and dynamic RAM refresh. And of course, all of the power of the 386 microprocessor.

One major advantage you gain by using one of these parts is that you can use standard PC development tools (compilers, assemblers, etc) for developing your applications. If you are already familiar with PC software development, the learning curve will be short, since these chips have the same basic architecture as the original 8088 (as used in the IBM/PC).

We're talking power here gang. Now let's all wait for Microsoft to release a version of Windows for embedded and real-time applications (Windows ET? Windows RT? Windows 2000? :-).

6805 (Motorola)

The 6805 is based loosely on the manufacturer's earlier 6800, with some similarities to the 6502. It has a Von-Neuman architecture in which instructions, data, I/O, and timers all share the same space. Stack pointer is 5 bits wide which limits the stack to 32 bytes deep. Some members of this family include on chip A/D, PLL frequency synthesizer, serial I/O, and software security.

68hc11 (Motorola and others)

The popular 68hc11 is a powerful 8-bit data, 16-bit address microcontroller from Motorola (the sole supplier) with an instruction set that is similar to the older 68xx parts (6801, 6805, 6809). The 68hc11 has a common memory architecture in which instructions, data, I/O, and timers all share the same memory space.

Depending on the variety, the 68hc11 has built-in EEPROM/OTPROM, RAM, digital I/O, timers, A/D converter, PWM generator, pulse accumulator, and synchronous and ansynchronous communications channels. Typical current draw is less than 20ma.

683xx (Motorola)

The MC68EC300 series incorporates various peripherals into various 68k family core processors. These can be called "integrated processors". They are really super-microcontrollers, very high performance, capable of high processing speeds, and able to address large amounts of memory. A typical example from this line would be the 68331. It is based on a 68020-like core and has about the same processing power as an Intel 80386.

PIC (MicroChip)

While watching my 8 year old daughter play with her Barbie Dolls (she has about 7 or so, including two that used to belong to Roz, my wife, when she was a girl) I noticed an interesting difference between the old dolls and the new dolls. The old Barbies could only move their heads sideways, while the new Barbies not only can move their heads sideways, but also up and down. AMAZING - the old Barbies were good girls - they could only say no. The new Barbies however can also say yes. Progress - isn't it wonderful! (Not to mention the gymnast Barbie that Dave Perry's daughter got for Christmas - "wait'll you see what *she* can do ;-)"

Which leads me to an amazing fact. Most everyone thinks of the PIC microcontroller line as being a recent introduction. However, they've been popular for over 20 years. What's the difference? Microchip (which was originally [owned by] General Instruments), seems to have recreated this microcontroller into a product universally regarded as a powerful and cost effective solution. The new chips are fabricated in CMOS, some features have been added, and new family lines have been introduced.

The PIC microcontrollers were the first RISC microcontrollers. RISC generally implies that simplicity of design allows more features to be added at lower cost, and the PIC line is no exception. Although having few instructions (eg. 33 instructions for the 16C5X line versus over 90 for the Intel 8048), the PIC line has a wealth of features included as part of the chip. Separate buses for instructions and data (Harvard architecture) allows simultaneous access of program and data, and overlapping of some operations for increased processing performance. The benefits of design simplicity are a very small chip, small pin count, and very low power consumption.

PIC microcontrollers are rapidly gaining in popularity. They are being featured more and more often in construction projects in popular hobbyist magazines, and are chalking up a good number of design wins. Due to their low cost, small size, and low power consumption, these microcontrollers can now be used in areas that previously wouldn't have been appropriate (such as logic circuits). They are currently available in three lines: the PIC16C5x, PIC16Cxx, and PIC17Cxx families.

PSST! Hey kid! Want a naked Barbie Doll?!

COP400 Family (National Semiconductor)

The COP400 Family is a P2CMOS 4-bit microcontroller which offers 512 bytes to 2K ROM and 32x4 to 160x4 RAM. Packages are varied from 20 to 28 pin (DIP/SO/PLCC). Functions include Microwire, timers counters, 2.3 to 6.0 Volt operation, ROMless modes, and OTP support.

Far from being "old" technology - 4-bit microcontrollers are meeting significant market needs in more applications than ever before. The reason for the continuing strength of the COP400 family is its versatility. Over 60 different, compatible devices are available for a wide range of requirements. The first under $.50 microcontroller set a new standard of value for cost/performance.

COP800 Family (National Semiconductor)

The COP800 Basic Family is a fully static 8-bit microcontroller, fabricated using double metal silicon gate microCMOS technology. This low cost microcontroller contains all system timing, interrupt logic, ROM, RAM, and I/O necessary to implement dedicated control functions in a variety of applications.

Depending on the device, features include: 8-bit memory mapped architect, MICROWIRE serial I/O, UART, memory mapped I/O, many 16 bit timer/counters with capture registers, a multi-sourced vectored interrupt, comparator, WATCHDOG Timer and Clock monitor, Modulator/Timer (high speed PWM timer for IR transmission), 8-channel A/D converter with prescaler and both differential and single-ended modes, brownout protection, halt mode, idle mode, high current I/O pins with 15mA sink capability, Schmitt trigger inputs and Multi-Input-Wake-Up. Most devices operate over a voltage range from 2.5V to 6V.

High throughput is achieved with an efficient, powerful instruction set operating at a 1uS per instruction rate (most instructions are single byte/single cycle) including true bit manipulation and BCD arithmetic instructions. Most devices have military versions for -55C to +125C.

HPC Family (National Semiconductor)

The HPC Family of High Performance microControllers is a 16-bit controller fabricated using National's advanced microCMOS technology. This process combined with an advanced architecture provides fast, flexible I/O control, efficient data manipulation, and high speed computation.

With its 16x16 bit multiply and 32x16 bit divide, the HPC is appropriate for compute-intensive environments that used to be the sole domain of the microprocessor. The architecture is a Von-Neuman architecture where the program and data memory share the same address space.

Depending on the family member, features include: 16-bit memory-mapped architecture with software configurable external address/data bus, Microwire/Plus serial I/O, UART, 16-bit timer/counters with input capture capability, High-Level Data Link Control (HDLC) for ISO-standard data communications, 8-channel A/D converter with prescaler and both differential and single-ended modes, power-saving modes, Multiply/Accumulate Unit with built-in circular buffer management for low to medium DSP applications, software configurable chip-select outputs, 64KB address space directly addressable, low-voltage (3.3V) operation.

High throughput is achieved with an efficient, powerful instruction set operating at a 50ns per instruction cycle (most instructions are single byte/single cycle) including true bit manipulation. Key applications currently using the HPC family include: Anti-lock Braking Systems, Hard Disk drives for mass storage, telecommunications, security systems, laser printers, and some military applications.

Project Piranha (National Semiconductor)

Project Piranha is an internal code name for National Semiconductor's embedded RISC processor technology. The Piranha technology represents the first RISC processor specifically designed for the needs of embedded applications. This was accomplished through examination of the needs of typical embedded applications, resulting in a technology which maintains the benefits of CISC while providing the performance of RISC.

Specifically, some of these benefits are: compact code density --> smaller memory usage/ lower system cost small core size --> more room for add-on system design scalable architecture --> a range of performance solutions from 8 to 64 bits with a common architecture common instruction set --> you only face the learning curve and development tools once modular design --> designed for easy integration of specialized functions into single chip

This technology is initially being implemented in application specific products from National Semiconductor, with the first product being available in Q1, 1995. For further information on this technology, please contact Mark Throndson at [email protected], or (408) 721-4957.

Z8 (Zilog)

A "loose" derivative of the Zilog Z80, the Z8 is actually a composite of several different achitectures. Not really compatible with the Z80 peripherals. Has a unique architecture with three memory spaces: program memory, data memory, and a CPU register file. On-chip features include UART, timers, DMA, up to 40 I/O lines. Some versions include a synchronous/asynchronous serial channel. Features fast interrupt response with 37 interrupt sources. The Z8671 has Tiny Basic in ROM. The Super-8 is just that, a super version of the Z8 with more of everything.

HD64180 (Hitachi)

A powerful microcontroller with full Z80 functionality plus: extended memory management, two DMA channels, synchronous and asynchronous communications channels, timers, and interrupt controller. Some versions of this chip also include EPROM, RAM, and PIO (programmable input/output). It runs Z80 code in fewer clock cycles than the Z80 and adds in hardware multiply and a few other instructions. Available in versions that run up to 18MHz.

TMS370 (Texas Instruments)

It is similar to the 8051 in having 256 registers, A and B accumulators, stack in the register page, etc. It also has a host of onboard support devices, some members have all of them while others have a subset, the peripherals include: RAM, ROM (mask, OTP, or EEPROM), 2 timers (configurable as timers/ counters/comparators/PWM output), watchdog timer, SCI (syncronous serial port), SPI (asynchronous serial port), A/D (8 bit, 8 channel), interrupts.

Instruction set is mostly 8 bit with some 16 bit support. Has several addressing modes, 8x8 multiply, 16/8 divide. Clock speeds are up to 20MHz which gives 5MHz for buss access and instruction cycles. Pins mostly TTL compatible (except clock and reset).

Packages include: 28,40 DIP 28 CLCC 28,44,68 PLCC 40,64 SDIP

A developers/proto board is available. It is a multi layer PCB about 12"x7" with RS-232 serial I/O, and monitor as well as access to all processor pins on a patch and proto area. Support software includes IBM-PC monitor & loader, cross assembler (absolute only). A pure serial TTY monitor is also supported. Sole power requirement is +5v. Priced is about $500 or so.

A relocating assembler and linker, and a C compiler are also available.

1802 (RCA)

This is a real old-timer. The 1802 is the successor to the 1801 (2 chip set) which was the first microprocessor implemented in CMOS. Both products were called microprocessors by RCA, not microcontrollers. However, since the 1801 was implemented in CMOS and therefore had low power requirements, it was often used in microcontroller applications. The 1802, with its higher level of integration and ease of use, could actually be considered a true microcontroller. The 1802 is radiation hard and used in a lot of deep space and satellite applications.

The 1802 has a fairly clean instruction set, a bunch of general-purpose registers (more like a Z80 than an 8051 in that regard), and separate data and I/O address spaces.

MuP21 (Forth chip)

The MuP21 was designed by Chuck Moore, the inventor of Forth. With the MuP21, Forth can compile into machine code and still be Forth, because the machine code IS Forth. The MuP21 freaks out at 100 MIPS while consuming only 50 milliwatts. Not only that, the chip includes a video generator, has only about 7000 transistors (that's right, 7000 and not 7,000,000), and costs about $20.

The assembler on this chip is a sort of dialect of Forth, as the CPU is modeled after the Forth virtual machine. MuP21 is a MINIMAL Forth engine. In fact MuP21 was designed to run OKAD (Chuck Moore's VLSI CAD softare), and OKAD was designed to run on MuP21. OKAD was run on a 486 to design MuP21, and MuP21 was designed to have just enough hardware to run OKAD about ten times as fast as a 486 on a very cheap chip (the MuP21). That's the reason for the MuP21's on-chip video generator coprocessor. The CPU programs the video generator and then just manipulates the video buffer. It is composite video out, so it only needs one pin. MuP21 is only a 40 pin chip.

MuP21 chips, boards, software, manuals, and spec sheets are available from: Offete Enterprises 1306 South B Street, San Mateo CA 94402 (415) 574-8250 Email: [email protected]

F21 (Next generation Forth chip)

F21 will be bigger (10k vs 7k transistors for the MuP21!) but since it is going to implemented with a smaller geometry (.8 micron vs 1.2) it will still be extremely small and low power, and low cost. Although the specs on this chip aren't final yet, expected performance is in the range of 250 MIPS!!. It will have multiple analog processors and a very high speed serial network coprocessor on chip. F21 will also support a wider range of memory chips and have more I/O processors.

Designed for cheap consumer multimedia and parallel processing, the F21 is planned for release some time in 1995.

For more information on this project, contact: Jeff Fox <[email protected]>.

6) GETTING STARTED WITH MICROCONTROLLERS

In order to get started with microcontrollers, several factors need to be considered. - cost - convenience - availability of development tools - intended use

The hardware described in this section is readily available, affordable, and is easy to find software for.

<Inclusion or exclusion of a product in this section doesn't have any real significance. I've tried to give a good cross-section of devices and manufacturers - I'm open for suggestions.>

6.1) Evaluation Kits/Boards

Many manufacturers offer assembled evaluation kits or boards which usually allow you to use a PC as a host development system. Among some of the more popular evaluations kits/boards are:

Parallax Basic Stamp This is a small single-board controller that runs BASIC, and costs only $39. A SIP version for only $29 is also available. THE 256 byte EEPROM can hold a program of up to about 100 instructions. The BASIC Stamp Programming Package is a complete development package for only $99. Parallax, Inc., 3805 Atherton Rd. 102, Rocklin, CA 95765 (916)624-8333 Fax: (916)624-8003 BBS: (916)624-7101 email: [email protected]

Motorola EVBU, EVB, EVM, EVS A series of very popular evaluation/development systems. Comes complete with the BUFFALO monitor and varying types of development software. Commonly used for university courses.

Dallas Semiconductor DS5000TK The DS5000TK allows evaluation of any DS5000 series device in any existing application without circuit changes. The included DS5000T plugs into the supplied serial interface pod which provides a connection to a host PC. A target cable connects the pod to the target system. Programs can be downloaded directly to the chip (no EPROM programming!) using the built-in serial loader. (With Dunfield's Development System, you end up with a cheap "pseudo-ice". Dunfield also has a circuit if you want to build a similar device.)

Philips DS750 For $100, you get a "pseudo-ice" for testing your code in-circuit. Based on the low-end Philips 87c75x parts. Allows source-code debugging in assembler (included), C, and PL/M, with an interface similar to that of Borland's Turbo Debugger. Very popular with students and consultants for experimenting with 80c51 code. Includes a VERY NICE book which describes the theory of operation of the board itself, and includes a good number of experiments that you can try for yourself. Philips sold nearly 10,000 of these boards in the USA (and 5000 in Europe without even advertising).

National Semiconductor's EPU The COP8780 Evaluation / Programming Unit (EPU) offers designers a low-cost ($125) tool for an introduction to National's COP8 Basic Family of 8-bit microcontrollers. This development tool gives you an inexpensive way to benchmark and evaluate microcontroller code in realtime. With its built in MIRCOWIRE/PLUS interface, it can interface to numerous MICROWIRE/PLUS devices such as EPROMS, EEPROMS, D/As, A/Ds, DASs, and others, to give a full featured system. The system includes the EPU board, assembler and debugger software, sample code, very limited C compiler, wall power supply, documentation, and a really great box :-).

6.2) Easy chips to use

In addition, several chips provide a similar capability if you are willing to spend a bit of time wiring up a simple circuit. A few chips worth looking at are:

Motorola MC68HC11A8P1 Contains Motorola's BUFFALO monitor which has the same functionality as the one on Motorola's evaluation boards. A working system can be built with this chip and a Maxim MAX-232. You can talk to it with a PC or Mac over a 3-wire RS232 connection. It is easy to load and run anything you want in the on-board RAM and EEPROM. You can even use subprograms in the BUFFALO monitor after getting a listing from Motorola's BBS or ftp site. This BBS/ftp site also has freeware assemblers to make a complete development environment cheaply and quickly.

Intel 8052AH-BASIC This popular chip with hobbyists is another easy way to get started. You can download high level code from your host. The disadvantages are that you can't get away from a multi-chip solution, the code is noticeably slow, you have to buy an MCS BASIC manual, you are detached from the inner workings, there aren't many on-chip goodies like A/D, and you can forget about running off of a battery.

Dallas Semiconductor DS5000/DS2250 These are well suited even for electronics ignoramuses (ignorami?) such as myself. All you need to add is a crystal and two capacitors to end up with a working system. These chips come complete with non-volatile RAM in the form of static RAM (at least 8K) backed up with a lithium battery. Everything is saved - program, data, and bugs ;-).

MicroChip PIC '5x series With only 33 instructions, this chip is definitely easy to use! Using Parallax's assembler, the instruction set is ** MUCH ** less intimidating than MicroChip's opcodes! These chips simply need power, ground, and 1 of 4 different timing circuits. Doesn't get much easier than that! With I/O pins that are beefy (25mA per pin sink, 20mA per pin source) and drive both high and low, interfacing is super easy. It's great to hook LEDs and such directly to output pins with only a resister in-line!

6.3) Software (Cheap and easy)

You can search for free software for development, but you often get what you pay for. What is sorely lacking in freeware is technical support. Several packages are available that provide complete development environments for some of the more popular microcontrollers. If you want to be productive right away, think about investing $100 or so - it'll be well worth the price!

I've been playing with the Dunfield Development System lately (on the 8051), and it's really quite nice. I've also heard many good things about it from others. It includes a near ANSI-C compiler, run-time library with source, assembler, ROM debugger, integrated development environment, monitor with source, utilities, and other extras. Although not freeware, the low price ($100), the features, all of the extra goodies, and the good reviews make this a package worth looking at. Also, if you're interested in working on more than one family of microcontroller, Dunfield supports a wide range. This means only needing to learn one system, instead of many. The following chips are supported: 6805, 6809, 68hc11, 68hc16, 8051/52, 8080/85, 8086, and 8096. A package including a simulator and a resident monitor debugger are also available for the 8051 for $50. Dunfield Development Systems P.O. Box 31044, Nepean, Ontario K2B 8S8 Canada (613)256-5820 Fax: (613)256-5821 Email: [email protected]

A decent C compiler for the 68hc11 comes from ImageCraft. This package, which runs under DOS and OS/2, includes a near ANSI C compiler, assembler, linker, librarian, ANSI C functions and headers, and 90 page manual. The current release is version 1.02 of their compiler. The price is just $40. Initial feedback on this compiler seems promising. The pre-release versions are already in use by many of you, and will still be available as freeware. ImageCraft P.O. Box 64226, Sunnyvale, CA 94086-9991 (Richard Man) [email protected]

Another low priced ($100) C compiler comes from Micro Computer Control. Cross compilers running under DOS are available for the 8051 and the Z8 (including Super-8). This package includes a C compiler, assembler, linker, librarian, and extensive printed documentation. A simulator/source code debugger is available for an additional $79.95. Micro Computer Control Corporation PO Box 275, 17 Model Ave., Hopewell, NJ 08525 (609)466-1751 Fax: (609)466-4116 BBS: (609)466-4117 Email: 73062.3336@compuserve.com

C isn't the only development system available (yeah, I know that's hard to believe) - good solid Basic and Forth development systems are also available. Refer to the appropriate FAQ for the microcontroller that you are using for more information on free and commercial development systems.

If the Microchip PIC is your game, then check out the Parallax tools (available on their ftp and web sites). All Parallax software is available free of charge to all takers! This includes PSIM (a PIC simulator), PASM (an assembler for '5x parts), and PASMX (an assembler for 'xx parts). These are the full commercial versions, not hobbled in any way!

7) MICROCONTROLLER PROGRAMMING LANGUAGES

Just a bit of an introduction for the beginner.

7.1) Machine/Assembly language

Machine language is the program representation as the microcontroller understands it. It is not easy for humans to read and is a common cause of migraine headaches. Assembly language is a human-readable form of machine language which makes it much easier for us flesh and bone types to deal with. Each assembly language statement corresponds to one machine language statement (not counting macros).

An assembly/machine language program is fast and small. This is because you are in complete charge of what goes into the program. Of course, if you write a slow, large, stupid program, then it will run slowly, be too big, and be stupid. Assembly language (assembler) can't correct stupidity - although sometimes I wish it could ;-).

If you are starting out learning about microcontrollers, it would be worth your while first learning assembler. By programming in assembler, you master the underlying architecture of the chip, which is important if you intend to do anything significant with your microcontroller.

7.2) Interpreters

An interpreter is a high level language translator that is closer to natural language. The interpreter itself is a program that sits resident in the microcontroller. It executes a program by reading each language statement one at a time and then doing what the statement says to do. The two most popular interpreters for microcontrollers are BASIC and FORTH.

BASIC's popularity is due to its simplicity, readability, and of course just about everyone has at least played with BASIC at one time or another. One common compaint about [interpreted] BASIC is that it is slow. Often this can be solved by using a different technique for performing the desired task. Other times it is just the price paid for using an interpreter.

FORTH has a very loyal following due to its speed (approaching that of assembler language) and its incremental approach to building a system from reusable parts. Many FORTH systems come with a host system which turns your desktop computer into a development system. FORTH can be quite difficult to write in (if you have no experience with it) and is probably even harder to read. However, it is a very useful and productive language for control systems and robotics, and can be mastered in time.

The nicest thing about developing a system with an interpreter is that you can build your program interactively. You first write a small piece of code and then you can try it out immediately to see how it works. When the results are satisfactory, you can then add additional components until the final product is achieved.

7.3) Compilers

A compiler is a high level language translator that combines the programming ease of an interpreter with greater speed. This is accomplished by translating the program (on a host machine such as a desktop PC) directly into machine language. The machine language program is then burned onto an EPROM or downloaded directly to the microcontroller. The microcontroller then executes the translated program directly, without having to interpret first.

The most popular microcontroller compilers are C and BASIC. PL/M, from Intel, also has some popular support due to that company's extensive use of that language.

Due to both its popularity and its slow speed, it was only logical that BASIC would appear as a compiled language. A few companies supply a BASIC compiler for several of the more popular microcontrollers. Execution speed is drastically increased over interpreted BASIC since the microcontroller is freed from the task of interpreting the statements as the program runs.

While interpreted Forth approaches (and sometimes surpasses) the speed of many compilers, compiled Forth screams along. Today there are many high performance optimizing native code Forth compilers, and there are also lots of very cheap or free public domain Forths. Some of them like Tom Almy's ForthCMP produces optimized native code with less overhead and better performance than just about anything else out there. Of course it still has compactness and more elegant factoring of functionality than in most languages.

C is now the language of choice for the entire universe. C is used on computers from the tiny microcontroller up to the largest Cray supercomputer. Although a C program can be a bit tedious at times to read (due to the terse programming style followed by many C programmers), it is a powerful and flexible development tool. Although a high level language, it also gives the developer access to the underlying machine. There are several very good and cheap C compilers available for the more popular microcontrollers. It is widely used, available, supported, and produces fairly efficient code (fast and compact).

7.4) Fuzzy Logic and Neural Networks

Fuzzy Logic and neural networks are two design methods that are coming into favor in embedded systems. The two methods are very different from each other, from conception to implementation. However, the advantages and disadvantages of the two can complement each other.

The advantage of neural networks is that it is possible to design them without completely understanding the underlying logical rules by which they operate. The neural network designer applies a set of inputs to the network and "trains" it to produce the required output. The inputs must represent the behavior of the system that is being programmed, and the outputs should match the desired result within some margin of error. If the network's output does not agree with the desired result, the structure of the neural network is altered until it does. After training it is assumed that the network will also produce the desired output, or something close to it, when it is presented with new and unknown data.

In contrast, a fuzzy-logic system can be precisely described. Before a fuzzy control system is designed, its desired logical operation must be analyzed and translated into fuzzy-logic rules. This is the step where neural networks technology can be helpful to the fuzzy-logic designer. The designer can first train a software neural network to produce the desired output from a given set of inputs and outputs and then use a software tool to extract the underlying rules from the neural network. The extracted rules are translated into fuzzy-logic rules.

Fuzzy logic is not a complete design solution. It supplements rather than replaces traditional event control and PID (proportional, integral, and derivate) control techniques. Fuzzy logic relies on grade of membership and artifical intelligence techniques. It works best when it is applied to non-linear systems with many inputs that cannot be easily expressed in either mathematical equations used for PID control or IF-THEN statements used for event control.

In an effort to change fuzzy logic from a "buzzword" (as it is in most parts of the world) to a well established design method (as it is in Japan), most manufacturers of microcontrollers have introduced fuzzy logic software. Most software generates code for specific microcontrollers, while other generates C code which can be compiled for any microcontroller.

8) DEVELOPMENT TOOLS

Having a programming language is usually not enough to develop a program for a microcontroller. Some way of debugging your program is needed. I am only too painfully aware of this fact.

8.1) Simulators

A simulator runs your microcontroller program on a host machine (such as your PC). You can step through the code to see exactly what is happening as the program runs. Contents of registers or variables can be altered to change the way the program runs. Eliminates (or at least delays) the erase/burn/program EPROM cycle common in microcontroller program development. You can work out ideas or learn about microcontrollers by experimenting with small code fragments and watching on the screen what happens. A simulator can't support real interrupts or devices, and usually runs much slower than the real device the program is intended for.

Some manufacturers have a cross between a software simulator and the hardware emulator - a hardware simulator. This is a piece of equipment that plugs into your target, and the pins will toggle and react like they should - just MUCH slower. Cost of a device like this is only about $100. Two such boards by National Semiconductor and Philips are detailed in section 6.2.

8.2) Resident Debuggers

A resident debugger runs your program on the microcontroller itself, while showing the progress on your host machine (such as a PC). Has many of the same advantages as simulator above, with the additional benefit of seeing how the program runs on the real target machine. A resident debugger needs to "steal" some resources from the target machine, including: a communications port to communicate with the host, an interrupt to handle single stepping, and a certain amount of memory for the resident part (on the target) of the debugger.

8.3) Emulators

If you've got the money, this is the equipment you want to develop your system with (yeah, that's right, a preposition at the end of a sentence!). A [usually] expensive piece of hardware that even for the cheaper versions will run you at least $700. An emulator is a sophisticated device that pretends that it is the microprocessor itself, while at the same time capturing information. It provides full and total control over your target, while at the same time not requiring any resources from the target. The emulator can either be a stand alone device with its own display, or it can be interface to a PC.

8.4) Good Stereo System

This is the most important tool for the microcontroller developer, or for any computer system developer for that matter. Don't expect to get anywhere unless you have the proper music playing in the background(?) at the proper volume. I find that I do my best work with the Rolling Stones (especially Goats Head Soup) or Clapton (especially early stuff like Cream - Disraeli Gears is a killer album!). The volume must be set to cause excrutiating pain to be most effective. Trust me on this ;-).

Tom Mornini of Parallax reports: "Johnny Cash also has a certain effectiveness, as well as the Beatles, Aerosmith, and Rush! 60's rock and British invasion bands in particular seem to have a particularly productive effect."

This would be an interesting topic for an in-depth study. Particularly intriguing, is if certain types of music work better with specific [families of] processors. Another question in need of study would be if it's really true that the smaller the chip (in bits), the louder the music needs to be.

9) FINDING OUT MORE ABOUT MICROCONTROLLERS

If you are interested in learning more about microcontrollers, there are many fine sources of information. You have your choice of printed media (books, periodicals, informative graffiti) or interactive (right here on the Internet, or BBSs).

9.1) Books

8-bit Microcontroller Instruction Set Performance - Digitial Systems Consulting / June 1994 - compares Motorola's M68HC05, Intel's 80x51, Microchip's PIC16C5x, and National's COP8 - lit number 630008 - (800)272-9959 call this number for copies

The 16 bit 8096: Programming, Interfacing, Applications - Ron Katz and Howard Boyet - Microprocessor Training Inc 14 East 8th Street, New York, NY 10003 212-473-4947 - Library of Congress Catalog card number: 85-61954 - According to William Chernoff: "The book is pretty good - mostly software examples. The one hardware thing I looked closely at was wrong - a schematic error. Oh well."

The 68hc11 Microcontroller - Joseph D. Greenfield (at R.I.T.) - Saunders College Publishing, (Harcourt Brace Jovanovich) - 1992 - ISBN 0-03-051588-2 - A number of the sections make use of the Buffalo monitor. This could be useful if you are using the Motorola Trainer EVB.

The 8051 Family of Microcontrollers -Richard H. Barnett -Prentice-Hall, 1995 (yeah, that's right, 1995!) -ISBN 0-02-306281-9

8051 Interfacing and Applications - Applied Logic Engineering 13008 93rd Place North, Maple Grove, MN 55369 - (612)494-3704

The 8051 Microcontroller - I. Scott MacKenzie - Macmillan Publishing Company, 1992 - includes schematics for a single-board computer, assembly-language source code for a monitor program, and interfaces to a keypad, LEDs, and loudspeaker.

The 8051 Microcontroller - James W. Stewart - Regents/Prentice-Hall, 1993 - $27.50, 273 pages - includes many interfacing examples (switches, solenoids, relays, shaft encoders, displays, motors, and A/D converters) and a chapter on top-down design method

The 8051 Microcontroller: Architecture, Programming and Applications - Kenneth J. Ayala - 241 pages, soft cover - 5.25" diskette with assembler and simulator - ISBN 0-314-77278-2, Dewey 004.165-dc20 - West Publishing Company P.O. Box 64526, St. Paul, MN 55164 (800)328-9352 - see review in next section

The Art of Programming Embedded Systems - Jack G. Ganssle - 1992, 279pp, $55.00 - ISBN: 0-12-274880-0 - CONTENTS: Introduction, Initial Considerations. Elegant Structures. Designs for Debugging. Design for Test. Memory Management. Approximations. Interrupt Mamangement. Real-Time Operating Systems. Signal Sampling and Smoothing. A Final Perspective. Appendixes: Magazines, File Format. Serial Communications. Bibliography. Index.

Assembly Language Programming (for the MCS-51 family) - F. A. Lyn - L. S. Electronic Systems Design

Basic-52 Programmer's Guide - Systronix, Inc. (they also sell a Basic compiler) - address above

Beginner's Guide - Suncoast Technologies

A Beginners Guide to the Microchip PIC - Nigel Gardner - Character Press, Ltd. (UK) - ISBN 1 899013 00 8 - software (on floppy) and hardware guide, debugging techniques - suitably titled, for those with no previous microcontroller experience - 19.95 UK Pounds

The PIC Source Book: - assembly language source code on diskette - $39 - Scott Edwards Electronics 964 Cactus Wren Lane, Sierra Vista, AZ 85635 (602)459-4802 Fax: (602)459-0623 72037.2612@compuserve.com

C and the 8051 - Thomas W. Schultz - Prentice Hall - ISBN 0-13-753815-4

Data Acquisition and Process Control with the M68HC11 Microcontroller - Frederick Driscoll, Robert Coughlin, Robert Villanucci of Wentworth Institute of Technology. - Macmillan Publishing Company - 1994 - ISBN 0-02-33055-X - Several Chapters on the 68HC11, instructions, and EVB; chapters on interfacing Analog and Digital signals to the 68HC11; example applications of interfaces to temperature, load cell, pressure and thermocouple sensors. - a good companion to Motorola's "pink" books

Data book / Handbook / Users' Guide - Advanced Micro Devices - Dallas (User's guide for the DS5000) - Intel - Siemens

Design with Microcontrollers - John B. Peatman - ISBN 0-07-049238-7 - This book is on a more advanced level. Uses both the 68hc11 and Intel 8096 as example systems. - Used for a very popular course on microcontroller design at Georgia Tech.

Embedded Controller Forth for the 8051 Family - Academic Press - William H. Payne - uses a Forth development system available on the Internet

Embedded Controllers Databook 1992 Edition - National Semiconductor Corporation - literature number: 400049 - (800)272-9959 call this number for for copies

Embedded Systems Programming in C and Assembler - John Forrest Brown - Van Nostrand Reinhold, 1994 - 304 pages, $49.95 - ISBN 0-442-01817-7 - covers Motorola and Intel processors - includes diskette with code from the book - book review in Dr. Dobb's Journal, November 1994, page 121

Experimenter's guide - Rigel Corporation

Introduction to Microcontroller Design, Based on the 8051 family of Processors - Business Data Computers P.O. Box 1549, Chester, CA 96020

M68hc11 Reference Manual - Motorola - literature reference M68HC11RM/AD - This document is the "bible" of the 6811 and is a must-have for any serious 6811 programmer.

MC68hc811E2 Programming Reference Guide - Motorola - literature reference M68HC811E2RG - A pocket-sized guide to the version of the 6811 used on the Mini Board

The Microcontroller Idea Book - Jan Axelson (of Microcomputer Journal fame) - features the 8052-BASIC microcontroller - hands-on guide with complete plans (schematics, design theory, program listings, construction details, etc) - explains how to use sensors, relays, displays, clock/calendars, keypads, wireless links, and more - 1994, 273 pages, $31.95 + shipping - Lakeview Research, 2209 Winnebago St., Madison, WI 53704 (608)241-5824 Internet: 71163.3555@compuserve.com - contact the author at [email protected]

Microcomputer Engineering - Gene H. Miller - Prentice Hall, Englewood Cliffs, NJ 07632 - 1993 - ISBN 0-13-584475-4 - Explains the basics. Many clear and concise assembly language example programs. - Written to be used with the Motorola Trainer (EVB).

Microcontroller Technology, The 68hc11 - Peter Spasov - Prentice Hall - ISBN 0-13-583568-2

Microcontrollers: Architecture, Implementation, and Programming - Kenneth Hintz and Daniel Tabak - McGraw-Hill Inc. 1992 - ISBN 0-07-028977-8

PIC 16Cxx Development Tools instructions manuals - Parallax, Inc. - Instruction manual for the Parallax PIC assemblers - Instruction manual for the Parallax Software Simulator - Instruction manual for the Parallax PIC programmer hardware - Details the Parallax PIC instruction set

PIC 16Cxx Applications Handbook - Parallax, Inc. - Contains condensed data sheets for '5x, '64, '71, and '84 controllers - Contains 14 application notes showing circuits and code for common projects using the PIC series of microcontrollers.

Posix.4: Programming for the Real World - Bill O. Gallmeister - O'Reilly and Associates, 1995 - ISBN 1-56592-074-0 - Part I of the book describes the Posix standard (what it is, what it isn't, and what it's for), and explains the principles of real time programming (tasking, messages, scheduling, I/O, and performance) and why Unix isn't fit for real-time programming. Part II is a reference on the Posix functions and header files. Part III contains much of the code for the exercises in the book.

Programmer's Guide to the 1802 - Tom Swan - Hayden Book Company, Inc., 1981 - ISBN 0-8104-5183-2 - good introduction to assembly language progamming and an thorough tutorial on the 1802

Programming Microcontrollers in C - Ted Van Sickle - HighText Publications, 1994 - 394 pages, $29.95 - ISBN 1-878707-14-0 - thorough tutorial on C programming, covers aspects of C programming specific to embedded systems - covers the Motorola line of microcontrollers (small to large) - book review in Dr. Dobb's Journal, November 1994, page 121

The Real-Time Kernel - Jean Labrosse - R&D Publications, Inc. Suite 200 1601 W 23rd St., Lawrence, KS 66046 - (913)841-1631 Fax: (913)841-2624 - Based on the article "A Portable Real Time Kernel in C" in Embedded Systems Programming (Part 1: vol 5 no 5 May 1992, Part 2: vol 5 no 6 June 1992) - originally written for the Intel 186 but ported to HC11 source code for UCOS11

Single- and Multiple-Chip Microcomputer Interfacing - G.J. Lipovski - Copyright 1988 - 478 pages - ISBN 0-13-810557-X (Prentice-Hall Edition) ISBN 0-13-810573-1 (Motorola Edition) - Based around the 68HC11 it covers both hardware and software at undergraduate level, but the emphasis is on interfacing. - Chapter titles: 1 Microcomputer Architecture 2 Programming Microprocessors 3 Bus Hardware and Signals 4 Parallel and Serial I/O 5 Interrupts and Alternatives 6 Analog Interfacing 7 Counters and Timers 8 Communications Systems 9 Storage and Display Systems

Single- and Multiple- Chip Microcomputer Interfacing (Lab Manual) - Peter Song and G. Jack Lipovski - Prentice-Hall, 1988 - ISBN 0-13-811605-9 - Support for the above book. Examples based around the Motorola EVB and the BUFFALO monitor or the EVBU (or 3-chip micro) and PC-Bug11.

User Manual for the CDP1802 COSMAC Microprocessor - RCA, 1977 - contains useful hardware and software techniques

9.2) Data and Reference Books

Motorola - M68hc11 Reference Manual, ref # M68HC11RM/AD this document is the "bible" of the 6811 and is a must-have for any serious 6811 programmer contact Motorola at 800-521-6274 (in the U.S.) to get a free copy of this manual - MC68hc811E2 Programming Reference Guide, ref # M68HC811E2RG a pocket-sized guide to the version of the 6811 used on the Mini Board, "ownership of this handy reference is proof of being a true 6811 nerd" - by Fred Martin

National Semiconductor - (800)272-9959 for copies - COP8 Databook, ref # 400007 - COP8 Selection Guide, ref # 630006 - COP8 Designers Information Kit, ref # 6300007-005 contains: - COP8 Databook (1994 Edition) - COP8 Selection Guide (1994 Edition) - Independent 8-bit Instruction Set Analysis - Independently prepared software analysis of National's COP8, Motorola's M68Hc05, Intel's 80X51, and Microchip's PIC16C5X - Utility and Overview Disks - Self-lead overview on COP8, includes electronic selection guide and sample application code - COP8 Utility Disk, Mac ref # 6300000, Windows ref # 630001 typical microcontroller applications and sample code available by ftp nscmicro.nsc.com in/pub/COP8 - COP8 Overview Disk, Mac ref # 630004, Windows ref # 630005 self-lead COP8 overview, shows product features/benifits and includes a electronic selection guide (2 disks) available by ftp nscmicro.nsc.com in /pub/COP8

 
To the best of our knowledge, the text on this page may be freely reproduced and distributed.
If you have any questions about this, please check out our Copyright Policy.

 

totse.com certificate signatures
 
 
About | Advertise | Bad Ideas | Community | Contact Us | Copyright Policy | Drugs | Ego | Erotica
FAQ | Fringe | Link to totse.com | Search | Society | Submissions | Technology
Hot Topics
Essential Programs Thread
Your tech related job
Split Hard Drive???
computer crashed
Intel's Q6600
Unlock My Phone
opening a .iso file without writing it?
best laptops
 
Sponsored Links
 
Ads presented by the
AdBrite Ad Network

 

TSHIRT HELL T-SHIRTS