Planet Arduino

It is almost impossible these days to find a PC with old ISA card slots. Full size PCI card slots are in danger of going the same way. Many PCs today feature PCI Express connectors. PCI Express offers a lot of advantages including a small size, lower pin count, and a point-to-point serial bus topology that allows multiple simultaneous transfers between different pairs of end points. You’ll find PC Express connectors in things other than PCs too, including a lot of larger embedded systems.

If you ever wanted to prototype something on PCI Express, you’d usually turn to an FPGA. However, [moonpunchorg] posted a workable design for an Arduino on a mini PCI Express board. (As [imroy264] points out in the comments, the board is using the USB port present on the PCI-E connector.) The design files use KiCAD so it should be fairly easy to replicate or change. Naturally, there are pins on the edges to access I/O ports and power. You do need to use ISP to program the Arduino bootloader on the chip.

The board appears to a host computer as a SparkFun as a Pro Micro 3.3V board, and from there you could easily add function to a computer with a PCI Express slot using nothing more than the Arduino IDE. The board is known to work with the VIA VAB-600 Springboard and VIA VAB-820 boards, although it is likely to work with other PCI Express hosts, too.