Here is another project which proves the versatility of the Nokia 3310 display, with a few components you can have a thermometer with graphical display. In many cases the 3310 display is to small, well for this application it fits like a glove, the sensor is the DS1621 with i2c interface, this way you can learn also how to use the AVR two wire interface to, don’t be afraid of the graphical display, you will find plenty of example source code and library.
Estimating from the price drop of LCD technology, the commonly used two row alpha numeric displays will be obsolete in a few years, its time to migrate to graphical!
AVR thermometer+Nokia display: [Link]
There many devices which can be controlled trough relays, like light bulbs, pumps, motorized doors, and the list can go on. Most of the relay boards available on the web are based on the serial interface, this has some drawbacks: limited distance, about 15meter based on the RS232 standard, and the new generation of motherboards lack this port. The presented board has ethernet interface using the ENC28J60 and the PIC18F4680, it also has a Real Time Circuit with battery backup, the ethernet interface beside its speed has a major advantage, the RJ45 contains a coupling transformer which is used to galvanically isolate the local electronics ground from the bus, this doesn’t mean that it will support a 230 common mode voltage, but offers protection to a certain limit.
The ethernet interface shows its full potential when comes along with a webserver, fortunately the author thought this to, he developed a simple web server which runs on the PIC, this way you can control the relays trough your network or even the internet.
Ethernet relay board: [Link]
This is the most advanced DIY metering device I have seen on the web with open source hardware and software, it has two 0-10VDC range and one auto range 0-30VDC voltmeter, one channel 0-3A high side amp meter, four channel logic analyzer, pulse/sine/triangle waveform generator and frequency counter, it has a simple PC interface, which makes all the functions easily accessible. Did I mentioned that even the PC software is open source?
Be aware though that isn’t a hand held multimeter, it doesn’t have any protection for over voltage, and it is connected to your PC the trough the serial port, so be careful not to fry your computer, I recommend this instruments to people who work with micro controllers, or low voltage electronics powered trough a power supply which has a transformer, this way you and your computer are on the safe side of the wall outlet.
AVR bench instrument: [Link]
It’s great fun building robots, the most simple one is a vehicle robot, in other words a small car, the next step is to add some remote control, wireless off course, by wireless most of you probably think of radio control, yes that has long range, works trough obstacles, maybe even trough solid walls, but building one can be a real challenge, and buying one can be expensive. The author of this project solved this issue by using a simple TV remote control.
The original project is quite limited regarding the functions, only forward and reverse controls are possible, since it has just one motor, but it’s easy to improve the design, my choice would be to use two motors, each with separate H bridge, this is the easiest way the steer it.
The source code is written for ICC compiler and is made available for download, if you adapt it to AVR-GCC then you can adapt it to work with any type of remote control and start adding some intelligence to the robot, like line following, maze solving and many more.
IR remote robot: [Link]
Yes, it is an Arduino board, but I omitted to mention in the title not to discourage those who doesn’t have one, because the project needs just a few passive components beside the ATmega168 you can even build it on a breadboard.
The project is a great example of the AVR micro controllers speed since it does a real-time audio signal sampling and output on the PWM channel, it has also a couple of audio effects like reverberation, overtone. Because it isn’t a dedicated audio DPS it has some limitations, like 15kHz sampling rate, 512byte ring buffer, 8bit PWM which handles the digital to analog conversion, so don’t expect for high quality sound output. Consider this a scaled down audio effect generator, it covers the basic effects and is a great introduction for more complex audio processing
ATmega audio processing: [Link]
