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I'd like to start messing around programming and building something with an Arduino board, but I can't think of any great ideas on what to build. Do you have any suggestions?
I show kids, who have never programmed, or done any electronics before, to make a simple 'Phototrope', a light sensitive robot, in about a day. It costs under £30 (GBP) including Arduino, electronics and off-the-shelf mechanics. If folks really get into mobile robots, the initial project can grow and grow (which I feel is part of the fun).
There are international robot competitions which require relatively simple mechanics to get started, e.g. in the UK http://www.tic.ac.uk/micromouse/toh.asp
Ultimate performance require specially built machines (for lightness) , but folks would get creditable results with an Arduino Nano, the right electronics, and a couple of good motors.
A line following robot is the classic mobile robot project. The track can be as simple as electrical tape. Pololu have some fun videos about their near-Arduino 3PI robot. The sensors are about £1, and there are a bunch of simple motor+gearbox kits from lots of places for under £10. Add a few £ for motor control, and you have autonomous robot mechanics, in need of programming! Add an Infrared Remote receiver (about £1), and you can drive it around using your TV remote. Add a small solar cell, use an Arduino analogue input to measure voltage, and it can find the sun. With a bit more electronics, it can 'feed' itself. And so it gets more sophisticated. Each step might be no more than a few hours to a few days effort, and you'll find new problems to solve and learn from.
IMHO, the most interesting (low-cost) competitions are maze solving robots. The international competition rule require the robot to explore a walled maze, usually using Infrared sensors, and calculate their optimal route. The challenges include keeping track of current position to near-millimeter accuracy, dealing with real world's unpredictably noisy environment and optimising straight-line speed with shortest distance cornering.
All that in 16K of program, and 1K RAM, with real-time interrupt handling (as much as 100K interrupts/second for some motor systems), sensor sampling, motor speed control, and maze solving is an interesting programming challenge. (You might make it 'easy' with 32K of program, and 2K RAM :-)
I'm working on a 'constrained' robot challenge (based on Arduino) so that robot performance is mainly about programming rather than having a big budget.
Start small and build up to something more complex. Control servos. Blink LEDs. Debounce inputs. Read analog sensors. Display text on an LCD. Then put it together.
Despite the name, I like the "Evil Genius" book for PIC microcontrollers because of the small, easily digestible projects that tend to build on one another. It is, of course, aimed at PIC programmers rather than the Arduino, but the material covered will be useful no matter what you're developing on.
I know Arduino is trendy right now, but I also like the Teensy++ development board because of its low price-point ($24), breadboard-compatible PCB, relatively high pin count, Linux development environment, USB connectivity, and not needing a programmer. Worth considering for smaller projects.
If you come up with something cool, let me know. I need an excuse to do something fun :)
Bicycle-related ideas:
theft alarm (perhaps with radio link to a base station which is connected to a PC by Ethernet)
fancy trip computer (with reed switch or opto sensor on wheel)
integrate with a GPS telematics unit (trip logging) with Ethernet/USB download of logged data to PC. Also has an interesting PC programming component--integrate with Google Maps.
Other ideas:
Clock with automatic time sync from:
GPS receiver
FM radio signal with embedded RDS data with CT code
Digital radio (DAB+)
Mobile phone tower (would it require a subscription and SIM card for this receive-only operation?)
NTP server via:
Ethernet
WiFi
ZigBee (with a ZigBee coordinator that gets its time from e.g. Ethernet or GPS)
Mains electricity smart meter via ZigBee (I'm interested now that smart meters are being introduced in Victoria, Australia; not sure if the smart meters broadcast the time info though, and whether it requires authentication)
Metronome
Instrument tuner
This reverse-geocache puzzle box was an awesome Arduino project. You could take this to the next step, e.g. have a reverse-geocache box that gives out a clue only at a specific location, and then using physical clues found at that location coupled with the next clue from the box, determine where to go for the next step.
You could do one of the firefighting robot competitions. We built a robot in university for my bachelor's final project, but didn't have time to enter the competition. Plus the robot needed some polish anyway... :)
Video here.
Mind you, this was done with a Motorola HC12 and a C compiler, and most components outside the microcontroller board were made from scratch, so it took longer than it should. Should be much easier with prefab components.
Path finding/obstacle navigation is typically a good project to start with. If you want something practical, take a look at how iRobot vacuums the floor and come up with a better scheme.
Depends on your background and if you want practical or cool. On the practical side, a remote control could be a simple starting point. It's got buttons and lights but isn't too demanding.
For a cool project maybe a Simon-style memory game or anything with lights & noises (thinking theremin-style).
I don't have suggestions or perhaps something like a line follower robot. I could help you with some links for inspiration
Arduino tutorials
Top 40 Arduino Projects of the Web
20 Unbelievable Arduino Projects
I'm currently developing plans to automate my 30 year old model train layout.
A POV device could be fun to build (just google for POV Arduino). POV means persistence of vision.
As a hobby project to keep myself out of trouble, I'd like to build a little programmer timer device. It will basically accept a program which is a list of times and then count down from each time.
I'd like to use a C or Java micro controller. I have used BASIC in the past to make a little autonomous robot, so this time around I'd like something different.
What micro controller and display would you recommend? I am looking to keep it simple, so the program would be loaded into memory via computer (serial is ok, but USB would make it easier)
Just use a PIC like 16F84 or 16F877 for this. It is more than enough.
As LCD use a 16 x 2 LCD. It is easy to use + will give a nice look to your project.
LCD
The language is not a matter. You can use PIC C, Micro C or any thing you like. The LCD's interface is really easy to drive.
As other components you will just need the crystal and 2 capacitors as oscillator + pull up resister. The rest of the components depend on the input method that you are going to use to set the times.
If you are using a computer to load the list then you will need additional circuit to change the protocols. Use MAX 232 to do that. If you want to use USB, you need to go ahead and use a PIC with USB support. (18F series)
(source: sodoityourself.com)
This is a set of nice tutorials you can use. You can purchase the products from them as well. I purchased once from them.
I would go with the msp430. An ez430 is $20 and you can get them at digikey or from ti directly, then sets of 3 microcontroller boards for $10 after that. llvm and gcc (and binutils) compiler support. Super simple to program, extremely small and extremely low power.
There are many ways to do this, and a number of people have already given pretty good suggestions AVR or PIC are good starting points for a microcontroller to work with that doesn't require too much in the way of complicated setup (hardware & software) or expense (these micros are very cheap). Honestly I'm somewhat surprised that nobody has mentioned Arduino here yet, which happens to have the advantage of being pretty easy to get started with, provides a USB connection (USB->Serial, really), and if you don't like the board that the ATMega MCU is plugged into, you can later plug it in wherever you might want it. Also, while the provided programming environment provides some high level tools to easily protype things you're still free to tweak the registers on the device and write any C code you might want to run on it.
As for an LCD display to use, I would recommend looking for anything that's either based on an HD44780 or emulates the behavior of one. These will typically use a set of parallel lines for talking to the display, but there are tons code examples for interfacing with these. In Arduino's case, you can find examples for this type of display, and many others, on the Arduino Playground here: http://www.arduino.cc/playground/Code/LCD
As far as a clock is concerned, you can use the built-in clock that many 8-bit micros these days provide, although they're not always ideal in terms of precision. You can find an example for Arduino on doing this sort of thing here: http://www.arduino.cc/playground/Code/DateTime. If you want something that might be a little more precise you can get a DS1307 (Arduino example: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1191209057/0).
I don't necessarily mean to ram you towards an Arduino, since there are a huge number of ways to do this sort of thing. Lately I've been working with 32-bit ARM micros (don't do that route first, much steeper learning curve, but they have many benefits) and I might use something in that ecosystem these days, but the Arduino is easy to recommend because it's relatively inexpensive, there's a large community of people out there using it, and chances are you can find a code example for at least part of what you're trying to do. When you need something that has more horsepower, configuration options, or RAM, there are options out there.
Here are a few places where you can find some neat hardware (Arduino-related and otherwise) for projects like the one you're describing:
SparkFun Electronics
Adafruit Industries
DigiKey (this is a general electronics supplier, they have a bit of everything)
There are certainly tons more, though :-)
I agree with the other answers about using a PIC.
The PIC16F family does have C compilers available, though it is not ideally suited for C code. If performance is an issue, the 18F family would be better.
Note also that some PICs have internal RC oscillators. These aren't as precise as external crystals, but if that doesn't matter, then it's one less component (or three with its capacitors) to put on your board.
Microchip's ICD PIC programmer (for downloading and debugging your PIC software) plugs into the PC's USB port, and connects to the microcontroller via an RJ-11 connector.
Separately, if you want the software on the microcontroller to send data to the PC (e.g. to print messages in HyperTerminal), you can use a USB to RS232/TTL converter. One end goes into your PC's USB socket, and appears as a normal serial port; the other comes out to 5 V or 3.3 V signals that can be connected directly to your processor's UART, with no level-shifting required.
We've used TTL-232R-3V3 from FDTI Chip, which works perfectly for this kind of application.
There are several ways to do this, and there is a lot of information on the net. If you are going to use micro controllers then you might need to invest in some programming equipment for them. This won't cost you much though.
Simplest way is to use the sinus wave from the power grid. In Europe the AC power has a frequency of 50Hz, and you can use that as the basis for your clock signal.
I've used Atmel's ATtiny and ATmega, which are great for programming simple and advanced projects. You can program it with C or Assembly, there are lots of great projects for it on the net, and the programmers available are very cheap.
Here is a project I found by Googling AVR 7 segment clock.
A second vote for PIC. Also, I recommend the magazine Circuit Cellar Ink. Some technical bookstores carry it, or you can subscribe: http://www.circellar.com/
PIC series will be good, since you are creating a timer, I recommend C or Assembly (Assembly is good), and use MPLAB as the development environment. You can check how accurate your timer with 'Stopwatch' in MPLAB. Also PIC16F877 has built in Hardware Serial Port. Also PIC16F628 has a built in Hardware serial port. But PIC16F877 has more ports. For more accurate timers, using higher frequency oscillators is recommended.
I've experience in doing desktop and web programming for a few years. I would like to move onto doing some embed system programming. After asking the initial question, I wonder which hardware / software IDE should I start on...
Arduino + Arduino IDE?
Atmel AVR + AVR Studio 4?
Freescale HCS12 or Coldfire + CodeWarrior?
Microchip PIC+ MPLAB?
ARM Cortex-M3 + ARM RealView / WinARM
Or... doesn't matter?
Which development platform is the easiest to learn and program in (take in consideration of IDE usability)?
Which one is the easiest to debug if something goes wrong?
My goal is to learn about "how IO ports work, memory limitations/requirements incl. possibly paging, interrupt service routines." Is it better to learn one that I'll use later on, or the high level concept should carry over to most micro-controllers?
Thanks!
update: how is this dev kit for a start? Comment? suggestion?
Personally, I'd recommend an ARM Cortex-M3 based microcontroller. The higher-power ARM cores are extremely popular, and these low-power versions could very well take off in a space that is still littered with proprietary 8/16-bit cores. Here is a recent article on the subject: The ARM Cortex-M3 and the convergence of the MCU market.
The Arduino is very popular for hobbyist. Atmel's peripheral library is fairly common across processor types. So, it would smooth a later transition from an AVR to an ARM.
I don't mean to claim that an ARM is better than an AVR or any other core. Choosing an MCU for a commercial product usually comes down to peripherals and price, followed by existing code base and development tools. Besides, microcontrollers are general much much simpler than a desktop PC. So, it's really not that hard to move form one to another after you get the hang of it.
Also, look into FreeRTOS if you are interested in real-time operating system (RTOS) development. It's open source and contains a nice walk through of what an RTOS is and how they have implemented one. In fact, their walk-through example even targets an AVR.
Development tools for embedded systems can be very expensive. However, there are often open source alternatives for the more open cores like ARM and AVR. For example, see the WinARM and WinAVR projects.
Those tool-chains are based on GCC and are thus also available (and easier to use IMHO) on non-Windows platforms. If you are familiar with using GCC, then you know that there are an abundance of "IDE's" to suit your taste from EMACS and vi (my favorite) to Eclipse.
The commercial offerings can save you a lot of headaches getting setup. However, the choice of one will very much depend on your target hardware and budget. Also, Some hardware support direct USB debugging while others may require a pricey JTAG adapter.
Other Links:
Selection Guide of Low Cost Tools for Cortex-M3
Low-Cost Cortex-M3 Boards:
BlueBoard-LPC1768-H ($32.78)
ET-STM32 Stamp Module ($24.90)
New Arduino to utilize an ARM Cortex-M3 instead of an AVR microcontroller.
Given that you already have programming experience, you might want to consider getting an Arduino and wiping out the firmware to do your own stuff with AVR Studio + WinAVR. The Arduino gives you a good starting point in understanding the electronics side of it. Taking out the Arduino bootloader would give you better access to the Atmel's innards.
To get at the goals you're setting out, I would also recommend exploring desktop computers more deeply through x86 programming. You might build an x86 operating system kernel, for instance.
ARM is the most widely used embedded architecture and covers an enormous range of devices from multiple vendors and a wide range of costs. That said there are significant differences between ARM7, 9, 11, and Cortex devices - especially Cortex. However if getting into embedded systems professionally is your aim, ARM experience will serve you well.
8 bit architectures are generally easier to use, but often very limited in both memory capacity and core speeds. Also because they are simple to use, 8-bit skills are relatively easy to acquire, so it is a less attractive skill for a potential employer because it is easy to fulfil internally or with less experienced (and therefore less expensive) staff.
However if this is a hobby rather than a career, the low cost of parts, boards, and tools, and ease of use may make 8 bit attractive. I would suggest AVR simply because it is supported by the free avr-gcc toolchain. Some 8 bit targets are supported by SDCC, another open source C compiler. I believe Zilog make their Z8 compiler available for free, but you may need to pay for the debug hardware (although this is relatively inexpensive). Many commercial tool vendors provide code-size-limited versions of their tools for evaluation and non-commercial use, but beware most debuggers require specialist hardware which may be expensive, although in some cases you can build it yourself if you only need basic functionality and low speeds.
Whatever you do do take a look at www.embedded.com. If you choose ARM, I have used WinARM successfully on commercial projects, although it is not built-for-comfort! A good list of ARM resources is available here. For AVR definitely check out www.avrfreaks.net
I would only recommend Microchip PIC parts (at least the low-end ones) for highly cost sensitive projects where the peripheral mix is a good fit to the application; not for learning embedded systems. PIC is more of a branding than an architecture, the various ranges PIC12, 16, 18, 24, and PIC32 are very different from each other, so learning on one does not necessarily stand you in good stead for using another - often you even need to purchase new tools! That said, the dsPIC which is based on the PIC24 architecture may be a good choice if you wanted to get some simple DSP experience at the same time.
In all cases check out compiler availability (especially if C++ support is a requirement) and cost, and debugger hardware requirements, since often these will be the most expensive parts of your dev-kit, the boards and parts are often the least expensive part.
This is kind of a hard question to answer as your ideal answer very much depends on what it is your interested in learning.
If your goal is just to dive a little deeper into the inner workings of computing systems i would almost recommend you forgo the embedded route and pick up a book on writing a linux kernel module. Write something simple that reads a temperature sensor off the SMbus or something like that.
If your looking at getting into high level (phones, etc) embedded application development, download the Android SDK, you can code in java under eclipse and even has a nice emulator.
If your looking at getting into the "real" microcontroller space and really taking a look at low level system programming, i would recommend you start on a very simple architecture such as an AVR or PIC, something without an MMU.
Diving into the middle ground, for example an ARM with MMU and some sort of OS be it linux or otherwise is going to be a bit of a shock as without a background is both system programming and hardware interfacing i think the transition will be very rough if you plan to do much other than write very simple apps, counting button presses or similar.
Texas Instruments has released a very interesting development kit at a very low price: The eZ430-Chronos Development Tool contains an MSP430 with display and various sensors in a sports watch, including a usb debug programmer and a usb radio access point for 50$
There is also a wiki containing lots and lots of information.
I have already created a stackexchange proposal for the eZ430-Chronos Kit.
No it doesn't matter if you want to learn how to program an embedded device. But you need to know the flow of where to start and where to go next. Cause there are many micro-controllers out there and you don't know which one to choose. So better have a road-map before starting.
In my view you should start with - Any AVR board (atmega 328P- arduino boards or AVR boards)
then you should go to ARM micro-controller - first do ARM CORTEX TDMI
then ARM cortex M3 board.Thus this will give you an overall view after which you can choose any board depending on what kind of project you are working and what are your requirements.
Whatever you do, make sure you get a good development environment. I am not a fan of Microchip's development tools even though I like their microcontrollers (I have been burned too many times by MPLAB + ICD, too much hassle and dysfunction). TI's 2800 series DSPs are pretty good and have an Eclipse-based C++ development environment which you can get into for < US$100 (get one of the "controlCARD"-based experimenter's kits like the one for the 28335) -- the debugger communications link is really solid; the IDE is good although I do occasionally crash it.
Somewhere out there are ICs and boards that are better; I'm not that familiar with the embedded microcontroller landscape, but I don't have much patience for poor IDEs with yet another software tool chain that I have to figure out how to get around all the bugs.
Some recommend the ARM. I'd recommend it, not as a first platform to learn, but as a second platform. ARM is a bit complex as a platform to learn the low-level details of embedded, because its start-up code and initialisation requirements are more complicated than many other micros. But ARM is a big player in the embedded market, so well worth learning. So I'd recommend it as a second platform to learn.
The Atmel AVR would be good for learning many embedded essentials, for 3 main reasons:
Architecture is reasonably straight-forward
Good development kits available, with tutorials
Fan forum with many resources
Other micros with development kits could also be good—such as MSP430—although they may not have such a fan forum. Using a development kit is a good way to go, since they are geared towards quickly getting up-and-running with the micro, and foster effective learning. They are likely to have tutorials oriented towards quickly getting started.
Well, I suppose the development kits and their tutorials are likely to gloss over such things as bootloaders and start-up code, in favour of getting your code to blink the LED as soon as possible. But that could be a good way to get started, and you can explore the chain of events from "power-on" to "code running" at your pace.
I'm no fan of the PICs, at least the PIC16s, due to their architecture. It's not very C-friendly. And memory banks are painful.
It does matter, you need to gradually acquire experience starting with simpler systems. Note that by simpler I dont mean less powerful, I mean ease of use, ease of setup etc. In that vein I would recommend the following (I have no vested interest in a any of the products, I just found them the best):
I've started using one of these (MBED developer board). The big selling points for me were that I could code in C or C++, straightforward connection vis USB and a slick on-line development environment (no local tool installation required at all!).
http://mbed.org/
Five minutes afer opening box I had a sample blinky program (the 'hello world' of the emedded world) running the following:
#include "mbed.h"
DigitalOut myled(LED1);
int main()
{
while(1)
{
myled = 1;
wait(0.2);
myled = 0;
wait(0.2);
}
}
That's it! Above is the complete program!
It's based on ARM Cortex M3, fast and plenty of memory for embedded projects (100mhz, 256k flash & 32k ram). The online dev tools have a very good library and plenty of examples and theres a very active forum. Plenty of help on connecting devices to MBED etc
Even though I have plenty of experience with embedded systems (ARM 7/9, Renases M8/16/32, Coldfire, Zilog, PIC etc) I still found this a refreshingly easy system to get to grips with while having serious capability.
After initially playing with it on a basic breadboard I bought a base board from these guys: http://www.embeddedartists.com/products/lpcxpresso/xpr_base.php?PHPSESSID=lj20urpsh9isa0c8ddcfmmn207. This has a pile of I/O devices (including a miniture OLED and a 3axis accelerometer). From the same site I also bought one of the LCPExpresso processor boards which is cheap, less power/memory than the MBED but perfect for smaller jobs (still hammers the crap out of PIC/Atmega processors). The base board supports both the LCPExpresso and the MBED. Purchasing the LCPExpress processor board also got me me an attached JTAG debugger and an offline dev envoronment (Code Red's GCC/Eclipse based dev kit). This is much more complex than the online MBED dev environment but is a logical progression after you've gained expeience with the MBED.
With reference to my original point noite that the MBED controller is much more capable than the the LPCExpresso controller BUT is much simpler to use and learn with.
I use microchips PIC's, its what I started on, I mainly got going on it due to the 123 microcontroller projects for the evil genius book. I took a Microprocessors class at school for my degree and learned a bit about interrupts and timing and things, this helped a ton with my microcontrollers. I suppose some of the other programmers etc may be better/easier, but for $36 for the PicKit1, I'm too cheap to go buy another one...and frankly without using them I don't know if they are easier/better, I like mine and recommend it every chance I get, and it took me forever to really actually look at it, but I was able to program another chip off board with ICSP finally. I don't know what other programmers do it, but for me that's the nicest thing 5 wire interface and you're programmed. Can't beat that with a stick...
I've only used one of those.
The Freescale is a fine chip. I've used HC-something chips for years for little projects. The only caveat is that I wouldn't touch CodeWarrier embedded with a 10 foot pole. You can find little free C compilers and assemblers (I don't remember the name of the last one I used) that do the job just fine. Codewarrior was big and confusing and regardless of how much I knew about the chip architecture and C programming always seemed to only make things harder. If you've used Codewarrior on the Mac back in the old days and think CW is pretty neat, well, it's not at all like that. CW embedded looks vaguely similar, but it works very differently, and not very well.
A command-line compiler is generally fine. Professionals who can shell out the big bucks get expensive development environments, and I'm sure they make things better, but without that it's still far better than writing assembly code for a desktop PC in 1990, and somehow we managed to do that just fine. :-)
You might consider a RoBoard. Now, this board may not be what you are looking for in terms of a microcontroller, but it does have the advantage of being able to run Windows or DOS and thus you could use the Microsoft .NET or even C/C++ development tools to fiddle around with things like servos or sensors or even, what the heck, build a robot! It's actually kinda fun.
There's also the Axon II, which has the ATmega640 processor.
Either way, both boards should help you achieve your goal.
Sorry for the robotics focus, just something I'm interested in and thought it may help you too.
I use PICs, but would consider Arduino if I chose today. But from your goals:
how IO ports work
memory limitations/requirements
interrupt service routines
I wonder if you best bet is just to hack in the Linux kernel?
BBC Micro Bit
https://en.wikipedia.org/wiki/Micro_Bit
This cheap little board (~20 pounds) was crated by ARM Holdings as an educational device, and 1M units were given out for free to UK students.
It contains an ARM Cortex-M0, the smallest ARM core of all.
I recommend it as a first micro-controller board due to its wide availability, low cost, simplicity, and the fact that it introduces you to the ARM architecture, which has many more advanced boards also available for more serious applications.
How can I make my own microcontroller? I've done some work using GAL chips and programmed a chip to do simple commands such as add, load, move, xor, and output, but I'd like to do something more like a real microcontroller.
How can I go about doing this? I've read a little bit about FPGA and CPLD, but not very much, and so was looking for some advice on what to get and how to start developing on it.
Look here for a good wiki book. I had some coursework I wrote when I was teaching Electronic Eng, but I couldn't find it around. When I was teaching, most of the students were happy to use the schematic capture tools in the Xilinx Foundation package. They've moved onto ISE and WebPACK now. You can download the WebPack for free, which is useful, and it has schematic capture and simulation in it.
If you really want to shine, learn VHDL or Verilog (VHDL seems to be more common where I've worked, but that is only a small smattering of places) and code the design rather than enter it through the GUI.
If you know ANYTHING at all about digital logic design (and some HDL) I rekon you can have a somewhat functional 8-bit microprocessor simulating in VHDL in about 2 days. You're not going to build anything blazingly fast or enormously powerful in that time but it's a good starting point to grow from. If you have to learn about digital design, factor in a couple of days to learn how the tools work and simulate some basic logic circuits before moving onto the uP design.
Start learning the basics of digital systems, and how to build a binary adder. Move on to building an ALU to handle addition, subtraction, and, or, xor, etc and then a sequencer to read opcodes from RAM and supply them to the execution unit.
You can get fancy with instruction set design, but I'd recommend starting out REALLY simple until you have your head around whats going on, then throw it out and start again with something more complex.
Once you have the design simulating nicely you can gauge its complexity and purchase a device to suit. You should look at a development system for the device family you've chosen. Pick a device bigger than what you need for development because it's nice to be able to add extra instrumentation to debug it when it's running, and you almost certainly won't have optimized your design in the early stages of getting it on the device.
EDIT: Colin Mackenzie has a good tutorial about uC design and some FPGA boards as well as a bit of other stuff.
You may want to have a look around OpenCores.org, a "forge" site for open source IP core development. Also, consider getting yourself a development board like one of these to play around with.
Much of the tools ecosystem revolves around VHDL, although Avalda is working on tools to compile F# for FPGAs.
I saw a textbook once that stepped through building a machine from TTL chips. This had the same instruction set as a PDP-8, which is very - and I mean very - simple, so the actual machine architecture is easy to implement in this way.
The PDP-8 FAQ mentions a book: "The Art of Digital Design," second edition, by Franklin Prosser and David Winkel (Prentice-Hall, 1987, ISBN 0-13-046780-4). It also mentions people implementing it in FPGA's.
Given the extreme simplicity of this CPU architecture and availability of PDP-8 code or reference implementations it might be a good starting point to warm up with.
Alternatively, an acquaintance of mine implemented a thumb (cut down ARM) on a FPGA as a university project run by one Steve Furber (a prominent Acorn alumnus). Given that this could be compressed into a format small enough for a university project it might also be a good start.
To play with soft-core microprocessors, I like the Spartan 3 Starter Board from Digilent just because it has 1M of static RAM. SDRAM and DDR RAM are harder to get going, you know.
The leds, switches and a simple serial interface are a plus to debug and communicate.
As someone already pointed out, OpenCores.org is a good place to find working examples. I used the Plasma uC to write some papers while on university.
A microcontroller can be as simple as a ROM (instruction*2^x + (clock phase) is the address, outputs are the control signals, and you're good to go). Or it can be a complex harry beast with three arms and branch prediction support hardware.
Can you give more details about your aspirations?
After searching some very helpful links by all of you, I came across this Wikiversity course.
One of the first sentences is, "Have you ever thought to build your own microprocessor?"
Xilinx has a MicroBlaze and a PicoBlaze soft controller for its FPGAs. The latter is free, while, IIRC, the Microblaze is to be paid for.
As its name suggests the PicoBlaze is a small processor, which has its limitations, but OTOH is compact enough to run on a CPLD. Anyway a nice processor to get you started.
Pablo Bleyer has a PicoBlaze-compatible PacoBlaze. PacoBlaze was written in Verilog (which, like Adam said, less common than VHDL).
You need a big fpga for a little mcu.
You need a fpga with the correct hardware blocks if you need things like AD.
You need a soft core to put into the fpga.
But how about to just play around with a normal MCU before this project,
so you kind of know where you are going? How about some AVR:s from Atmel.
You can get free samples of pic micro controllers at this site. Last I knew, you don't even have to pay shipping.
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=64
I would like to create/start a simulator for the following microcontroller board: http://www.sparkfun.com/commerce/product_info.php?products_id=707#
The firmware is written in assembly so I'm looking for some pointers on how one would go about simulating the inputs that the hardware would receive and then the simulator would respond to the outputs from the firmware. (which would also require running the firmware in the simulated environment).
Any pointers on how to start?
Thanks
Chris
Writing a whole emulator is going to be a real challenge. I've attempted to write an ARM emulator before, and let me tell you, it's not a small project. You're going to either have to emulate the entire CPU core, or find one that's already written.
You'll also need to figure out how all the IO works. There may be docs from sparkfun about that board, but you'll need to write a memory manager if it uses MMIO, etc.
The concept of an emulator isn't that far away from an interpreter, really. You need to interpret the firmware code, and basically follow along with the instructions.
I would recommend a good interactive debugger instead of tackling an emulator. The chances of destroying the hardware is low, but really, would you rather buy a new board or spend 9 months writing something that won't implement the entire system?
It's likely that the PIC 18F2520 already has an emulator core written for it, but you'll need to delve into all the hardware specs to see how all the IO is mapped still. If you're feeling up to it, it would be a good project, but I would consider just using a remote debugger instead.
You'll have to write a PIC simulator and then emulate the IO functionality of the ports.
To be honest, it looks like its designed as a dev kit - I wouldn't worry about your code destroying the device if you take care. Unless this a runner-up for an enterprise package, I would seriously question the ROI on writing a sim.
Is there a particular reason to make an emulator/simulator, vs. just using the real thing?
The board is inexpensive; Microchip now has the RealICE debugger which is quite a bit more responsive than the old ICD2 "hockey puck".
Microchip's MPLAB already has a built-in simulator. It won't simulate the whole board for you, but it will handle the 18F2520. You can sort of use input test vectors & log output files, I've done this before with a different Microchip IC and it was doable but kinda cumbersome. I would suggest you take the unit-testing approach and modularize the way you do things; figure out your test inputs and expected outputs for a manageable piece of the system.
It's likely that the PIC 18F2520 already has an emulator core written for it,
An open source, cross-platform simulator for microchip/PICs is available under the name of "gpsim".
It's extremely unlikely that a bug in your code could damage the physical circuitry. If that's possible, then it is either a bug in the board design or it should be very clearly documented.
If I may offer you a suggestion from many years of experience working with these devices: don't program them in assembly. You will go insane. Use C or BASIC or some higher-level language. Microchip produces a C compiler for most of their chips (dunno about this one), and other companies produce them as well.
If you insist on using an emulator, I'm pretty sure Microchip makes an emulator for nearly every one of their microcontrollers (at least one from each product line, which would probably be good enough). These emulators are not always cheap, and I'm unsure of their ability to accept complex external input.
If you still want to try writing your own, I think you'll find that emulating the PIC itself will be fairly straightforward -- the format of all the opcodes is well documented, as is the memory architecture, etc. It's going to be emulating the other devices on the board and the interconnections between them that will kill you. You might want to look into coding the interconnections between the components using a VHDL tool that will allow you to create custom simulations for the different components.
Isn't this a hardware-in-the-loop simulator problem? (e.g. http://www.embedded.com/15201692 )