Sunday, 18 April 2010

Arduino on a budget - part 3


The best-made plans...

I'd hoped to build version two of Veroduino (my Arduino clone on a strip-board), using a narrower piece of strip-board than my first attempt. Alas, the new version was too narrow; if you use a crystal for the controller's oscillator you need to connect it to a couple of capacitors, and I couldn't find a workable layout in the limited space available.

I decided to use a SimmStick. SimmSticks have fallen out of fashion as the USB has taken over, but they still work well and I had a suitable board from Dontronics.

The SimmStick can take a 28 or 40-pin Atmel AVR micro-controller; it took an hour or so to polulate the board and check it out. I already had a motherboard which provides power and RS232 comms if required. I modified the motherboard by adding a 30-pin PCB header. That gave me access to all the lines of the SimmBus; these include the SDA and SCL signals needed for I2C, as well as Ground and the 5v supply needed by my I2C boards.

I now have a non-Arduino compatible board, using legacy technology, but it's good enough for me to carry on testing my I2C peripherals until my Arduino Component Kit arrives from Oomlout.

I can use the avr gcc toolchain to compile my test code, an avrisp programmer to connect it to my workstation's parallel port, and the open source avrdude program to upload my software to the board and verify it.

The board already drives my LED test board; tomorrow I plan to write code to drive my I2C LCD.

No comments:

Post a Comment