Poor mans AVR programmer from USB keyboard

In order to program AVR microcontrollers using ISP interface only four control signals are required – SCK, MISO, MOSI and RESET. Steve figured out that these signal could be controlled using USB keyboard three LED indicators and keyboard key. LEDs can be easily toggled using HID device specification. So these signals come from PC as MOSI, SCK and RESET. MISO was received from device as keyboard key presses. A little trick had to be done with optocoupler in order to achieve this. He wrote an avrdude interface driver for this programmer, so its pretty easy to use. Problem is that programming speed is slowish because of attempt to debounce MISO line. Anyway, this is great hack that might be useful for someone. Continue reading