USBasp (http://www.fischl.de/usbasp/) designed by Thomas Fischl is a very nice and cheap AVR ISP programmer. However the original version theoretically does not allow to program AVRs powered from voltages lower than 5V. Because I wanted to use it to program new AVRs working at c.a. 2V, I had to modify the original circuit. To keep design as simple as possible and to avoid using integrated level converters (which are sometimes difficult to buy), I have decided to use simple transistor keys with Schottky diodes to convert logic levels. Such keys however invert the signals, so I had to modify the firmware. Final result (schematic diagram and modified sources) are available on my website http://www.ise.pw.edu.pl/~wzab/usbasp_mv . I hope that someone may found it useful. -- Regards, WZab
USBasp programmer-modified to program AVR powered from 2V to 5V
Started by ●April 26, 2010