# How do I easily flip odd and even pins between a Raspberry Pi and Pi hat?

My group built a custom hat for a Pi but when we integrated it we discovered a problem with our implementation.

Our even and odd pins were reversed. On the Pi, the headers are

------------
2  4  6  ...
1  3  5  ...
------------


But our board has the pins

------------
1  3  5  ...
2  4  6  ...
------------


Our 40-pin headers are surface-mounted on the bottom, so we cannot easily turn it around or put it underneath. We can connect a bunch of jumper wires and the circuit works by flipping the order of pins, but it'd be great if there was an easier workaround.

Is there some kind of thing we could get to do the reversal, or should we just do a revision on the boards?

• Is the header compatible with an available ribbon cable connector? If it is, you can probably fix it by assembling connectors onto a ribbon cable, both on the same side of the cable but rotated opposite each other, and use that cable to connect between your two boards. Mar 30 '18 at 18:29
• Do a revision of the board, especially if you are wanting to distribute or sell this. Mar 30 '18 at 20:02