Programming adaptor for 8 and 28 pin AVR Microcontrollers using ISP
Ok...its not pretty, but its practical. The 20 pin connector at the far right is left over from a diffferent project and is no longer used.
This adaptor lets me program 8 or 20 pin DIP devices using the In-System Programmer (ISP) described in Atmel's AVR910 application note. This circuit provides power and clocks for the part to be programmed and power to the ISP circuit.
When programming 8 pin devices, the part is positioned toward pins 1 and 20 of the socket such that the 8 pins of the chip occupy the pins 1,2,3,4,17,18,19, abd 20 of the programming socket.In the case of an 8 pin part being programmed, the SPST switch that grounds pin 4 must to be closed.Conversely, when programming a 20 pint part, the switch on pin 4 must be open so the crystal can be used for the clock for the part being programmed.