What is it?

A very simple routing board for Raspberry Pi SBCs with 26 and 40 pin header that exposes and routes almost every special function SBC pin to a dedicated header footprint.

Why did you make it?

I wanted to use an old Raspberry Pi Type A model 1 mainly as an AVR ISP/JTAG programmer. Works with I2C/SPI EEPROMs too. Installing a GNU/linux distro make it possible to use it both as a local or remote programmer and like a serial converter too. Pinout is explained on board itself and it's possible to mount additional header to use it to debug another compatible board.

What makes it special?

Every single-in-line header has 3.3V on first pin, GND as the last pin and has 2.54mm pitch. The board routes signals directly so only 3.3V systems are usable with it just like connecting everything else directly on the Raspberry Pi itself.