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COP8 microcontroller FAQ |
Section 1 of 2 - Prev - Next
Archive-name: microcontroller-faq/COP8
Posting-Frequency: monthly (20thish of each month)
Last-modified: 20June1995
URL: http://www.nsc.com/
This article is a draft collection of information sources on the line of
National Semiconductor Corporation ("National") COP8 microcontrollers.
The following topics are addressed:
0) Changes Since Last Time
0.1) Why should I read this?
1) ABOUT THIS FAQ
1.1) Who put this FAQ together?
1.2) How can I contribute to this list?
1.3) What newsgroups will this FAQ be posted to?
1.4) May I post this FAQ to my local BBS?
1.5) Are there any FAQs pertaining to other microcontrollers?
2) ABOUT THE COP8
2.1) The COP8 microcontroller
2.2) COP8 flavors / Numbering Scheme
2.3) COP8 chips and approximate prices (in US $)
2.4) Advantages in implementing control applications on this
family of microcontrollers
2.5) Techy Details
2.5.1) How fast are the parts?
2.5.2) What is the operating voltage of the devices?
2.5.3) How can I guarantee that my program will run reliably?
2.5.4) What kind of power savings features are available?
2.5.5) What about EMI?
2.5.6) Instruction Set
2.5.7) Can I hook up a LED to pins direct?
3) COP8 PRODUCTS
3.1) FTP sites
3.2) BBSs
3.3) Free languages and development tools
3.4) Free C compilers
3.5) Plans for COP8-based boards
3.6) Commercially available products
3.7) Contacting National
4) COP8 DOCUMENTATION
4.1) Periodicals
4.2) Data Books / Application Notes
----------------------------------------------------------------------
0) Changes since Last Time
Added a reference to coptools@esd.nsc.com (a support line for help on
cop8 tools).
Somebody pointed out to me the other day - Since the COP8 and the 8051
are modified harvard - they can do a load/store instruction in one
instruction cycle. A Von Neuman machine can not do that. This makes
(for memory intensive applications) a harvard machine almost 2 times
as fast as a Von Neuman running at the same speed.....
Maybe architecture does make a difference on a 8-bit controller....
0.1) Why should I read this document?
The COP8 is a pretty cool 8-bit microcontroller that has never had a
lot of exposure into the hobbiest/smaller manufactures marketplace.
I would like to change that. (& on the internet the indiviaul can do
anything!)
In a nutshell, some of the strengths of the COP8 are:
o Efficient Instruction Set - 77% os instructions are single cycle/
single byte
o Efficient Input/Output utilization - i.e. on a 44-pin package > 80%
of this pins are devoted to I/O. Efficient pin usage facilitiates a
cleaner hardware design and smaller die size = Overall cost reduction
o Powerful Timers - i.e. processor-independent Pulse Width Modulation
(PWM) and capture capabiliy - less software and processor overhead
o Low Poer Consumption (Low Voltage / Low Current)
o Multi-Input Wake Up (MIWU) - Only COP8 offers this unique feature
o Wide range of temperature and power supply operation
o Low cost Basic Family to address low-end 8-bit applications and
feature family to address mid-to-high end 8-bit market
And the Opposite side to the coin (have to be fair):
o Difficult (i.e. none) external memory interface
o No Multipy / Divide instructions
o Multiply / Divide hardware only offered on a couple devices
o Lack of EEPROM, and LCD (Although they are working on it)
-----------------------------------------------------------------------
1) ABOUT THIS FAQ
1.1) Who put this FAQ together?
After reading the excellent FAQs on the 8051 (Intel/Phillips) and
the 68hc11 (Motorola) put together by Russ Hersch
(Nice work Russ), I decided to make a FAQ
on the COP8, National's family of 8-bit microcontrollers.
I work for National in the Geographic Business Unit (GBU) responsible for
technical support for New Business Development (NBD), so if you want to
call this advertising, and don't want me to continue to post this in
the future, please email me (that doesn't mean I will stop, but you
will get it off your chest ;-). I think that I have kept most of the
hype out - please let me know if you think otherwise.
This FAQ will hopefully give everyone a brief overview of why you should
have a further look at the COP8 instead of automatically picking a
HC11, or 8051. Not that they are bad parts, in fact they are better
at some things than the COP8. And COP8 is much better at some things
than the HC11 or 8051. The COP8 is a good chip, and well worth
learning and developing with. With everyone's help this FAQ should
turn out to be a useful document.
Because I admire Russ's FAQ's and I was too lazy to take the time to think
up my own format, I have copied his basic format and a couple of sections
(with his permission, of course).
1.2) How can I contribute to this list?
I ask that if you have any suggestions or additions, or you would like to
correct any of the information contained herein, please send me a note.
My Email address is: rgetz@esd.nsc.com
My Smail address is:
Robin Getz
National Semiconductor Corporation
MS 16-325
Santa Clara, CA, 94086
USA
I certainly hope that those of you who know of interesting items for
the COP8 will share with everyone by contributing to this list.
If you are a manufacturer and have an anonymous ftp site available
that supports the COP8, please let me know by Email so that I can
add it to this FAQ.
1.3) What newsgroups will this FAQ be posted to?
This FAQ will be posted to the following newsgroups:
comp.realtime Issues related to real-time computing.
comp.robotics All aspects of robots and their applications.
sci.electronics Circuits, theory, electrons and discussions.
comp.arch.embedded Embedded computer systems topics.
And sometime later, depending on what people think....
news.answers
comp.answers
sci.answers
The first four newsgroups often contain discussions, announcements,
or information on microcontrollers. Check them out from time to
time. By posting to the *.answers newsgroups, the FAQ will
automatically be archived. The archive name of this FAQ (also
included in the header) is: cop8-microcontroller-faq.
Items will be posted once a month. I can't promise that
it will be on time, but I hope to post it on the 25th of each month.
You may also want to check out the following newsgroups, since they
occasionally have items of interest for COP8 users.
comp.lang.misc
alt.comp.hardware.homebuilt
1.4) May I post this FAQ to my local BBS?
I am putting no restrictions on the use of this FAQ except - It must
be distributed in its entirety with the copyright notice, and no
financial gain may be realized from it. After all, I have spent, and
continue to spend, a lot of time on this, and the only thing that I
intend to gain from it is more information on the COP8, and getting
to know my fellow COP8 groupies better.
For this reason I have appended a copyright statement to the end of
this FAQ. I feel pretty silly doing this, but I just want to protect
myself. The copyright does not limit the use of this list for
non-commercial purposes. I hereby give my permission to one and all
to pass this list around and post it wherever you want - as long as
it is not for financial gain.
Thanks.
1.5) How about FAQs on other microcontrollers?
If anyone wishes to start a FAQ on another microcontroller, please
feel free to copy the format of this FAQ (I did). With a common
format, we will all benefit when trying to find information on a
particular microcontroller. If anyone has any comments on the format
itself, I'm open for suggestions.
Other Microcontroller FAQs
Subject: 68hc11 microcontrollers
Newsgroups: comp.realtime
comp.robotics
sci.electronics
Archive: rtfm.mit.edu :
/pub/usenet/comp.answers/microcontroller-faq/68hc11
/pub/usenet/sci.answers/microcontroller-faq/68hc11
/pub/usenet/news.answers/microcontroller-faq/68hc11
Maintainer: Russ Hersch
Email: sibit@datasrv.co.il
Subject: PIC microcontrollers
Newsgroups: comp.realtime
comp.robotics
sci.electronics
Maintainer: Tom Kellett
Tom@takdsign.demon.co.uk
Subject: 8051 microcontrollers
Newsgroups: comp.sys.intel
comp.realtime
comp.robotics
comp.lang.forth
sci.electronics
Archive: rtfm.mit.edu :
/pub/usenet/comp.answers/microcontroller-faq/8051
/pub/usenet/sci.answers/microcontroller-faq/8051
/pub/usenet/news.answers/microcontroller-faq/8051
Maintainer: Russ Hersch
Email: sibit@datasrv.co.il
Subject: Microcontroller primer and FAQ
Newsgroups: comp.sys.intel
comp.realtime
comp.robotics
sci.electronics
alt.comp.hardware.homebuilt
Archive: rtfm.mit.edu :
/pub/usenet/comp.answers/microcontroller-faq/primer
/pub/usenet/sci.answers/microcontroller-faq/primer
/pub/usenet/news.answers/microcontroller-faq/primer
Maintainer: Russ Hersch
Email: sibit@datasrv.co.il
Additional FAQs of interest
Subject: Robotics
Newsgroups: comp.robotics
Maintainer: Kevin Dowling
Email: nivek@ri.cmu.edu
Subject: Electronics
Newsgroups: sci.electronics
Maintainer: Filip Gieszczykiewicz
Email: filip@smi.med.pitt.edu
Subject: Real-time
Newsgroups: comp.realtime, comp.answers, news.answers
Archive: rtfm.mit.edu : pub/usenet/comp.realtime
Maintainer: Mark Linimon
Email: linimon@nominil.lonesome.com
Subject: Neural Networks
Newsgroups: comp.ai.neural-nets,comp.answers,news.answers
Archive: rtfm.mit.edu : pub/usenet/neural-net-faq
URL: http://wwwipd.ira.uka.de/~prechelt/FAQ/neural-net-faq.html
Maintainer: Lutz Prechelt
Email: prechelt@ira.uka.de
Subject: Fuzzy Logic
Newsgroups: comp.ai.fuzzy,comp.answers,news.answers
Archive: rtfm.mit.edu : pub/usenet/fuzzy-logic/
URL: http://www.cs.cmu.edu:8001/Web/Groups/AI/html/faqs
/ai/fuzzy/part1/faq.html (should be one line)
Maintainer: Mark Kantrowitz
Email: mkant+@cs.cmu.edu
Other useful articles are also available. One article provides a
tabular cross reference of features and pin counts. This lists was
compiled and is being maintained by Roger Nelson
.
For more information on various microcontrollers and their features,
refer to the Microcontroller primer and FAQ listed above. URL:
ftp://rtfm.mit.edu/pub/usenet/comp.answers/microcontroller-faq/primer
----------------------------------------------------------------------
2) ABOUT THE COP8
2.1) The COP8 microcontroller
General
Firstly - COP8 (Control Orientated Processor) actually stands for
something. (Although the rest of the numbering scheme leaves something
to be desired). This is not a failed microprocessor that was cut down for
8-bit control (like some others). This is a full featured microcontroller
designed for bit level control. (Although National does make a 32-bit
processor (32000), the COP8 has nothing to do with it).
The COP8 is a powerful 8-bit data, 15-bit address (32K max ROM)
microcontroller from National with an instruction set that is
similar (somewhat) to the 8051, although it is much easier for
the beginner to understand and pick up (In my unbasised opinion
of course :)
Depending on the variety, the COP8 has built-in EEPROM/OTPROM, RAM,
digital I/O, timers, A/D converter, PWM generator, and synchronous
and asynchronous communications channels (RS232 and MICROWIRE/PLUS).
Typical current draw is less than 12ma, with powerdown modes that
can reduce current draw to typically less than 1 uA. (Although I
have seen ***50nA***)
A typical COP8 contains:
- CPU with Boolean processor
- fully static processor
- up to vectored 14 interrupts: 2 are external (8 pins can
be ORed into one interrupt, for a total of 9 external)
- arbitration levels
- 1,2 or 3 16-bit timer/counters (min 1 max 3)
- programmable full-duplex serial port (UART/USART or
MICROWIRE/PLUS)
- up to 56 I/O lines (11 pins min + Vcc/GND/Reset/CKI/CKO)
- up to 512 bytes RAM (64 bytes min)
- up to 16K ROM/EPROM in some models (768 bytes min)
- new parts are LOW EMI (typically lower than 14dB emissions)
The COP8 peripherals are POWERFUL. The timer that you will find on
a COP8 is much more powerful than on a typical microcontroller.
I will get into this a little later.
The COP8 instruction set is optimized for the one-bit operations so
often desired in real-world, real-time control applications. The
Boolean processor provides direct support for bit manipulation. This
leads to more efficient programs that need to deal with binary input
and output conditions inherent in digital-control problems. Bit
addressing can be used for test pin monitoring or program control
flags.
Architecture
The COP8 is a modified Harvard architecture. With the Harvard
architecture, the ROM is separated from the data memory (RAM). Both
ROM and RAM have their own separate addressing space with separate
address busses (there are two 0 addresses - 1 for ROM, 1 for RAM). The
COP8, though based on the Harvard Architecture, permits transfers from
ROM to RAM (hence modified).
The CPU has an 8-bit accumulator (A) that all arithmetic operations go
into. Two 8-bit index registers are present (X, B) to provide indexing
to anywhere in the memory map. Having the two index registers means the
COP8 is very good for processing data. Although an 8-bit processor, the
COP8 has some 16 bit (and bigger) peripherals (timers, 24 by 8 divide,
16 by 8 multiply, 16-bit A/D). An 8 bit stack pointer is also present,
and instructions are provided for stack manipulation.
Feature Family / Basic Family
The COP8 family is divided into two families - the Basic Family and
the Feature Family. There is little difference between the devices
although the feature family has the following advantages:
- 7 more instructions (including PUSH and POP)
- 2 auto-reload registers on timers / Basic family only has one
- IDLE Mode (Basic family only offers HALT mode)
- powerful peripherals ( A/D, UART, high speed timers, WatchDog,
comparators, etc. )
Onboard subsystems
Timer - Main timer system comprises of a single 16-bit counter
(2 x 8-bit registers) clocked at tc (1MHz at Crystal frequency of
10MHz). Timers have at least one associated register and all Feature
Family devices have 2 registers. All timers have at least 1uSec
accuracy and some have 100nS - check datasheet for specific details.
Timers can be configured in the following methods:
- External Counter (clocked on positive or negative edge)
- Timer w/ Auto-Load Register (PWM output)
- Timer with Capture (triggered on positive or negative edge)
Pulse Stream Generators - Some of the devices have specific timers
that are 100ns resolution 16-bit PWM (Pulse Width Modulation) outputs
only.
Multi-Input Wakeup -The Multi-Input WakeUp (MIWU) 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
selectable 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).
A-D Converters - 8-bit, 8-channel (multiplexed input) SAR
(Successive Approximation Register). Two dedicated pins Vref and
Agnd are provided for voltage reference. The time required for an
A/D conversion is dependent on the prescaler (fast conversion = more
power consumed - you can run the microcontroller fast - and the A/D
slow). The A/D converter has the following different modes of
operation:
- One channel conversion then stop
- Any specific channel to be scanned continuously
- Any differential channel pair measurement and then stop
- Any differential channel pair be scanned continuously
It also has a device that supports single slope A/D - the device
contains a constant current source, a comparator, an analog
mutliplexer, and a couple of 16-bit timers. These can be configured to
give the designer a 16-bit (resolution - not accuracy) A/D converter.
UART / USART - Asynchronous or synchronous serial communication block.
Clock generation (for asynchronous operation) is very sophisticated -
standard baud rates (300,1200,2400,4800,9600,19200,38400) can be generated
without having to select some obscure crystal frequency (Run the
controller at full speed). Synchronous operations occur at 16 x the speed
of asynchronous. Framing formats supported are: 1 Start, 7,8 or 9 data,
Parity/No Parity, 1 or 2 stop. The Attention Mode (or Network Mode) is
also supported, whereby a single master / multi-slave environment is set
up. This is a *very* powerful feature that can be used almost anywhere
when you need to talk to more than one controller / CPU. Diagnostic
mode is also enhanced from a regular UART. Internally, the Transmit
Shift Register is "looped back" into the Receive Shift Register.
Externally the receiver input pin (RDX) is connected to the
transmitter output pin(TDX). This allows the external UART to do a
continuity check of the external lines.
MICROWIRE/PLUS - A Synchronous serial communications port, comprised
of Serial Clock (SK), Serial Data In (SI), Serial Data Out (SO) and
optional chip selects. There are many specific MICROWIRE, MICROWIRE/PLUS
and SPI devices, (the only difference between SPI and MICROWIRE is
when the data is shifted in - and with MICROWIRE/PLUS - you control that)
such as A/Ds, D/As, EPROM, FLASH, EEPROM, MUX's.....
Comparator - A differential comparator, with a pair of inputs (positive
and negative) and an output. The comparator can be software disabled (to
save power). The output can either be brought outside (via a pin) or left
as a bit somewhere inside the controller.
BrownOut - 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.
CAN - The COP8 supports applications which require a low speed CAN
interface. The interface is compatible with CAN Specification 2.0 part B,
without the capability to receive/transmit extended frames. However,
extended frames on the bus are checked and acknowledged according to the
CAN specification. The maximum bus speed achievable with the CAN interface
is a function of crystal frequency, message length and software overhead.
The device can support a bus speed of up to 1 Mbit/s with a 10MHz
oscillator and 2 byte messages.
Hardware Multiply / Divide - This block supports a 1 byte x 2 bytes
(3 byte result) multiply operation (in one instruction cycle - 1uS) or a
3 byte x 2 byte (2 byte result) divide operation (in two instruction
cycles - 2uS). There are no multiplication errors that can occur ( FFh x
FF FFh = FE FF 01h which fits in three bytes). Divide errors are trapped
(overflow FF FF FFh / 1h = FF FF FFh which is bigger than two bytes and
division by zero)
2.2) COP8 flavors / Numbering Scheme
All devices include at least one 16-bit timer, MICROWIRE/PLUS serial
interface, common pinouts, common instruction set and most are
available in ...
Basic Family Numbering Scheme
COP8720CJ-XXX/N
^^^^^^^^^ ^^^ ^
|||||| ||| \-- Package Type : N - DIP
|||||| ||| : WM - Surface Mount
|||||| ||| : V - PLCC
|||||| ||| : J - DIP Windowed
|||||| |||
|||||| \\\---- Unique ROM id Code assigned by National
|||||| NOTE: OTP and windowed parts do not have
|||||| this code
||||||
||||\\-------- Features : CJ - Brown-out,high speed timers,
|||| comparators,MIWU
|||| C - 16-bit timer
||||
|||\---------- Number of pins : 0 - 28/40/44 (depends on package)
||| : 1 - 28
||| : 2 - 20
||| : 3 - 16
||| : 8 - Indicates Feature Family
||| : 5 - Indicates Feature Family
||| : 4 - Indicates Feature Family
|||
||\------------ ROM/RAM : 2 - 1k ROM / 64 btyes RAM
|| : 4 - 2k ROM / 128 bytes RAM
|| : 8 - 4k ROM / 128 bytes RAM
||
|\------------- If 7 is there indicates Programmability (EPROM)
| If 6 is there indicates EEPROM for RAM
| If nothing indicates ROM device with volatile RAM
|
\-------------- Temp range : 6 - Military (-55C to +125C)
8 - Industrial (-40C to +85C)
9 - Commercial (0C to +70C)
Feature Family Numbering Scheme
COP8788EG-XXX/N-R
^^^^^ ^^^ ^^^ ^ \ - OTP Oscillator Option: R - RC
|| ||| ||| | X - Crystal
|| ||| ||| |
|| ||| ||| \-- Package Type : N - DIP
|| ||| ||| : WM - Surface Mount
|| ||| ||| : V - PLCC
|| ||| ||| : J - DIP Windowed
|| ||| |||
|| ||| \\\---- Unique ROM id Code assigned by National
|| ||| NOTE: OTP and windowed parts do not have
|| ||| this code
|| |||
|| ||\-------- Features : F - 2 timers, 8-bit, 8-channel ADC
|| || G - 3 timers, 2 comparators, UART
|| || C - 1 timer, CAN, 2 comparators
|| || S - 1 timer, 1 comparator, UART
|| || L - 2 timers
|| || K - 1 time, Analog block, 1 comparator
|| || W - 2 timers, 4 Pulse Stream Generators
|| || Hardware Multiply divide
|| ||
|| |\--------- ROM/RAM : B - 2k ROM / 64 RAM
|| | C - 4k ROM / 128 RAM
|| | E - 8k ROM / 256 RAM
|| | G - 16k ROM / 512 RAM
|| |
|| \---------- Number of pins : 8 - 40/44 (depends on package)
|| : 5 - 20
|| : 4 - 28
|| : 2 - Indicates Basic Family device
|| : 1 - Indicates Basic Family device
|| : 0 - Indicates Basic Family device
||
|\------------- If 7 is there indicates Programmability (EPROM)
| If 6 is there indicates EEPROM for RAM
| If nothing indicates ROM device with volatile RAM
|
\-------------- Temp range : 6 - Military (-55C to +125C)
8 - Industrial (-40C to +85C)
9 - Commercial (0C to +70C)
2.3) COP8 chips and approximate prices (in US $)
I am affiliated with the manufacturer of these devices, & you will most
likely be purchasing parts from a distributor. If I was to list prices,
some people would think that was pricing fixing - so I can't (& won't).
The below prices are subject to lots of things, where you live (prices
vary by region), package type (DIP, SO, PLCC), Temperature range
(Commerical, Industrial, Military) and volume. Contact your favorite
National Distributor for more info.
OTPs
-----------
Basic Family |ROM|RAM|DI| |PL|TI|CO|UA|MI|WD|Other
Device | 5000 | | |P |SO|CC|ME|MP|RT|WU|OG|
COP8780 | 3.25 | 4k|128|40| |44| 1| | | | |
COP8781 | 2.55 | 4k|128|28|28| | 1| | | | |
COP8782 | 2.30 | 4k|128|20|20| | 1| | | | |
COP8720CJ | 4.00 | 1k| 64|28|28| | 2| 1| | Y| Y|
COP8722CJ | 3.50 | 1k| 64|20|20| | 2| 1| | Y| Y|
COP8740CJ | 5.25 | 2k|128|28|28| | 2| 1| | Y| Y|
COP8742CJ | 4.40 | 2k|128|20|20| | 2| 1| | Y| Y|
Feature Family
COP8784BC | 7.90 | 2k| 64|28|28| | 2| 2| | Y| |CAN, Power-On-Reset
COP8788CF | 7.65 | 4k|128|40| |44| 2| | | Y| Y|8-bit 8-chan
COP8784CF | 7.40 | 4k|128|28|28| | 2| | | Y| Y|A/D
COP8788EG | 7.85 | 8k|256|40| |44| 3| 2| 1| Y| Y|
COP8784EG | 7.60 | 8k|256|28|28| | 3| 2| 1| Y| Y|
COP8788CL | 6.70 | 4k|128|40| |44| 2| | | Y| Y|
COP8784CL | 6.45 | 4k|128|28|28| | 2| | | Y| Y|
COP8788EK | 9.40 | 8k|256|40| |44| 3| 1| | Y| Y|Analog fncts
COP8784EK | 9.10 | 8k|256|28|28| | 3| 1| | Y| Y|(16-bit A/D)
Otherwise you can call Future Active Industrial @ 800-723-5817. They do
stock parts on the shelf, and should be able to ship within a day or
two. To find you favorite local distributor, please call National, and
I am sure that we should be able to tell you.
ROMmed - Check with your local National Distributor.
2.4) Advantages in implementing control applications on this
family of microcontrollers
Traditional architecture - Modified Harvard (separate RAM and ROM busses)
leads to an easy to learn device as well as speeding the device up. As your
first microcontroller, this is very well suited to learning.
More features - a COP8 is typically a "one-chip" solution since it always
includes such items as serial I/O, PWM, and many I/O lines, and typically
includes on board A/D, UARTs, and many timers.
Fast and effective - the architecture correlates closely with the problem
being solved (control systems). Specialized instructions mean that fewer
bytes of code need to be fetched and fewer conditional jumps are processed.
(77% on instructions are single byte/single cycle - this means smaller and
faster code).
Low cost - high level of system integration within one component, only a
handful of components needed to create a working system.
2.5) Techy Details
Not all of the below features are on all of the devices (check the
datasheet):
2.5.1) How fast are the parts?
The COP8 has a max Clock input (CKI) of 10MHz. Since the parts have a
divide by 10 internal clock, the instruction cycle time (tc) is 1Mhz
or 1us. Most internal devices are fed with tc. The UART is fed by tc
through a very complex divide and prescaler, which allows any standard
baud rate to be generated with almost any tc. (i.e. Get the baud rate
you want without having to purchase that 9.8746856MHz crystal!) Some
timers are fed with CKI, giving a PWM output with **100ns** resolution.
Hardware multiply/divide are fed with CKI allowing a 3 byte by 2 byte
multiply to be completed in 1us, and a 3 byte by 2 byte divide completing
in 2us.
The parts are also fast because most of the instructions execute in one
tc. (1us).
2.5.2) What is the operating voltage of the devices?
The operating voltage of most of the ROMmed devices is between 2.3 <->
6.0V
The operating voltage of most of the OTP's is between 4.5 <-> 5.5V. A low
voltage (2ishV) OTP is expected within 12 months.
2.5.3) How can I guarantee that my program will run reliably?
You can't.
Not COP8, nor any other microcontroller is guaranteed to operate when a
10MegaWatt Radar wave is passing through it. EMI can cause any
microcontroller to do *VERY* funny things. What your microcontroller can
do is provide a couple features to ensure that the application realizes
that funny things have gone on.
The COP8 provides 3 methods of trapping these types of events.
NOTE: these events are just as likely to happen on a HC11, 8051,
PIC, ect . . . COP8 just traps them.
SOFTWARE TRAP - since the Program Counter (PC) is 15 bits in length
(Max theoretical ROM space of 32K) and the biggest part we make (currently)
is a 16K part (and most smaller) there is a possibility that the PC could
point to ROM that does not physically exist. This will be trapped within
one tc (instruction cycle) and cause an interrupt to occur. The interrupt
will reload the PC with a known value (0x00FF) and go to that value. A
Software Trap is the only non-maskible interrupt on the COP8. This can also
be valuable when your program takes 4097 bytes (As most programs do) and
you have to use a part with an 8K ROM. The upper 4095 bytes of ROM are
physically there, but unused. If the PC does the funky chicken and points
to those ROM locations, is this trapped? (Well - I wouldn't ask the
question if I didn't have the answer). Yes, this can be trapped. The
best method of doing this is to load all unused ROM locations with 0x00.
(Software Trap is simple a 00 OpCode). Since this is an interrupt, your
interrupt handler can do anything it wants. (i.e. re-initialize the device)
WATCHDOG - In a well thought out program this works wonderfully. The
software designer knows exactly how long program execution takes, and
services a timer every so often. This time frame (the amount of time
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