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I would like to have Arduino operating in a CAN network. Does the software that provides OSI model network layer exist for Arduino? I would imagine detecting the HI/LOW levels with GPIO/ADC and sending the signal to the network with DAC. It would be nice to have that without any extra hardware attached. I don't mind to have a terminating resistor required by the CAN network though.
By Arduino I mean any of them. My intention is to keep the development environmen.
If such a software does not exist, is there any technical obstacle for that, like limited flash size (again, I don't mean particular board with certain Atmega chip).
You can write a bit banging CAN driver, but it has many limitations.
First it's the timeing, it's hard to achieve the bit timing and also the arbitration.
You will be able to get 10kb or perhaps even 50kb but that consumes a huge amount of your cpu time.
And the code itself is a pain.
You have to calculate the CRC on the fly (easy) but to implement the collision detection and all the timing parameters is not easy.
Once, I done this for a company, but it was a realy bad idea.
Better buy a chip for 1 Euro and be happy.
There are several CAN Bus Shield boards available (e.g: this, and this), and that would be a far better solution. It is not just a matter of the controller chip, the bus interface, line drivers, and power all need to be considered. If you have the resources and skills you can of course create your own board or bread-board for less.
Even if you bit-bang it via GPIO you would need some hardware mods I believe to handle bus contention detection, and it would be very slow and may not interoperate well with "real" CAN controllers on the bus.
If your aim is to communicate between devices of your own design rather than off-the shelf CAN devices, then you don't need CAN for that, and something proprietary will suffice, and a UART will perform faster that a bit-banged CAN implementation.
I don't think, that such software exists. CAN bus is more complex, than for example I2C. Basically you would have to implement functionality of both CAN controller and CAN transceiver. See this thread for more details (in German).
Alternatively you could use one of the CAN shields. Another option were to use BeagleBone with suitable CAN cape.
Also take a look at AVR-CAN.
Hi Im using the following RF module
http://www.apogeekits.com/rf_receiver_module_rx433.htm
on an embedded board with the PIC16F628A. Sadly, I realized that the signal strength was in analog form and couldn't get any ideas to get the RSSI reading off the pin because well my PIC is digital DUH!.
My basic idea was
To get the RSSI value from my Receiver
Send it to the PIC
Link the PIC to a PC via RS232
Plot a graph of time vs RSSI of the receiver (so I can make out how close my TX is to my RX)
I thought it was bloody brilliant at first but ive hit a dead end here. Any ideas on getting the RSSI data to my PC from this receiver would be nice.
Thanks in Advance
You can get a PIC that has an integrated ADC for sampling the analog signal. Or, you can use an external ADC chip to do the conversion. You would connect that to your PIC using SPI or I2C.
The simplest thing to do is obviously to use a more appropriate microcontroller - one with an ADC! There are many (most), including PICs (though that wouldn't be my first choice).
Attaching an external SPI or I2C ADC might be a bit tedious since having no SPI or I2C on your part, you'd have to bit-bash it. If you do that, use an SPI part - its simpler. Your sample rate will suffer and may end-up being a bit jittery if you are not careful.
Another solution is to use a voltage controlled PWM, then use the timer input capture to time the pulse width. That will give you good regularity and potentially good resolution. You can get a chip (example) to do that, or grow your own. That last option requires a triangle wave input as well as the measured (control) voltage, but on the same site...
In a similar vein, you could use a low frequency VCO (example) and use the output to clock one of the timers, then using a second timer periodically sampling the first and reset it. The count will relate to the voltage, though not necessarily a linear relationship, linearisation could be none on the PIC or at the receiving PC - I'd go for the latter - your micro will suck at arithmetic (performance wise) - even integer arithmetic, especially if it involves division.
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'd like to start out with the Arduino to make something that will (preferably) dim my room lights and turn on some recessed lighting for my computer when a button or switch is activated.
First of all, is this even possible with the Arduino?
Secondly, how would I switch on and off real lights with it? Some sort of relay, maybe?
Does anyone know of a good tutorial or something where at least parts of this are covered? I'll have no problems with the programming, just don't know where to start with hardware.
An alternative (and safer than playing with triacs – trust me I've been shocked by one once and that's enough!) is to use X-10 home automation devices.
There is a PC (RS232) device (CM12U UK or CM11 US) you can get to control the others. You can also get lamp modules that fit between your lamp and the wall outlet which allows you to dim the lamp by sending signals over the mains and switch modules which switch loads on and off.
The Arduino has a TTL level RS232 connector (it's basically what the USB connection uses) – Pins 0 and 1 on the Diecimila so you could use that, connect it via a level converter which you can buy or make and connect to the X-10 controller, theirs instructions on the on the Arduino website for making a RS232 port.
Alternatively you could use something like the FireCracker for X-10 which uses 310MHz (US) or 433MHz (UK) and have your Arduino send out RF signals which the TM12U converts into proper X-10 mains signals for the dimmers etc.
In the US the X-10 modules are really cheep as well (sadly not the case in the UK).
Most people do it using triacs. A triac is like two diodes in anti-parallel (in parallel, but with their polarity reversed) with a trigger pin. A triac conducts current in either direction only when it's triggered. Once triggered, it acts as a regular diode, it continues to conduct until the current drops bellow its threshold.
You can see it as a bi-directional switch on a AC line and can vary the mean current by triggering it in different moments relative to the moment the AC sine-wave crosses zero.
Roughly, it works like this: At the AC sine-wave zero, your diodes turn off and your lamp doesn't get any power. If you trigger the diodes, say, halfway through the sine's swing, you lamp will get half the normal current it would get, so it lights with half of it's power, until the sine-wave crosses zero again. At this point you start over.
If you trigger the triac sooner, your lamp will get current for a longer time interval, glowing brighter. If you trigger your triac latter, your lamp glows fainter.
The same applies to any AC load.
It is almost the same principle of PWM for DC. You turn your current source on and off quicker than your load can react, The amount of time it is turned on is proportional to the current your load will receive.
How do you do that with your arduino?
In simple terms you must first find the zero-crossing of the mains, then you set up a timer/delay and at its end you trigger the triac.
To detect the zero-crossing one normally uses an optocoupler. You connect the led side of the coupler with the mains and the transistor side with the interrupt pin of your arduino.
You can connect your arduino IO pins directly to the triacs' triggers, bu I would use another optocoupler just to be on the safe side.
When the sine-wave approaches zero, you get a pulse on your interrupt pin.
At this interrupt you set up a timer. the longer the timer, the less power your load will get. You also reset your triacs' pins state.
At this timers' interrupt you set your IO pins to trigger the triacs.
Of course you must understand a little about the hardware side so you don't fry your board, and burn your house,
And it goes without saying you must be careful not to kill yourself when dealing with mains AC =).
HERE is the project that got me started some time ago.
It uses AVRs so it should be easy to adapt to an arduino.
It is also quite complete, with schematics.
Their software is a bit on the complex side, so you should start with something simpler.
There is just a ton of this kind of stuff at the Make magazine site. I think you can even find some examples of similar hacks.
I use MOSFET for dimming 12V LED strips using Arduino. I chose IRF3710 for my project with a heat sink to be sure, and it works fine. I tested with 12V halogen lamp, it worked too.
I connect PWM output pin from Arduino directly to mosfet's gate pin, and use analogWrite in code to control brightness.
Regarding 2nd question about controlling lights, you can switch on/off 220V using relays, as partially seen on my photo, there are many boards for this, I chose this:
As a quick-start, you can get yourself one of those dimmerpacks (50-80€ for four lamps).
then build the electronics for the arduino to send DMX controls:
Arduino DMX shield
You'll get yourself both the arduino-expirience + a good chance of not frying your surrounding with higher voltage..