Negcon to PS3 adaptor. Page under construction.

Source code, schematic and compiled hex:
PS3negcon0.3.zip

Linked to suggestions in the Rapid Electronics online catalogue

1 x ATMega8-16PU
1 x 28-pin DIL socket

1 x 12Mhz crystal oscillator

1 x 1N4148 signal diode
2 x 3V6 500mw Zener diode

2 x 22pf ceramic capacitor
1 x 100nf ceramic capacitor
1 x 100uf electrolytic capacitor

1 x 2k2 resistors
2 x 4k7 resistors
2 x 68R resistors
3 x 10k potentiometers (and knobs!)

6 x push switches
3 x SPST toggle switches (optional)

1 x case

stripboard
connecting wire

1 x USB cable with type A plug
1 x Playstation controller extension cable

You will also need some way to connect the programmer. I used a 7-way single row header (cut down from 10-way plug/socket) wired to a 3+3 way header that plugs into the AVRISP programmer out. The single row header is connected directly by pins 17 - 23; I cut the leg off the DIL socket at pin 23 (PC0, unused) and connected that line to RESET. As AVcc/ARef and AGnd are connected to Vcc and Gnd respectively, I just left a gap at ARef and connected the programmer lines to the correct pins. (This will be clearer when I add some pictures!)