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GPIO Replicator
- Details
Connecting wires to the RPi PINs is quite easy but makes me nervous about making a short-circuit and burning the whole thing. Such a fear is, obviously, exaggerated. Damaging a RPi is not that easy. The first thing that breaks is the SD card and a card can be replaced or in lighter cases - formatted. Even that noone likes to reinstall the whole system and waste the time...
To make a random damage less likely and to get an easier connection method with screw terminals and also to finally and for good close the RPi case I made a PCB board, which according to some people I have found in the net, should protect the PINs.
My board is based on the project of Mike Cook, who proposed using 330R resistors to limit the current flow and 3V3 zener diodes to limit the voltage. I added two fuses on 3V3 and 5V pins to enable powering the whole RPi over those pins. Once the case is closed I plan to connect the power to the pins, not to the mini USB connector, which is protected against excessive current. The scheme of the board looks as follows:
I have the filing that soldering all those resistors, diodes and fuses is a bit exaggerated. I use so far only 2 pins... I cannot also say for sure that the whole protection makes real sense. When making a PCB the number of elements makes no difference and the soldering itself is fun. It therefore is, as it is - ready to be used when the RPi applications grow in numbers.
It was slightly difficult to plan the board as it was necessary to remember which side is which. The paths are on one side while the connectors on the other. It's easy to get fooled. After the board was ready I also found that the goldpins are too close to the screw terminal. The schemes presented above are already connected but the photo below shows the problem.
The dimensions of the board were chosen to fit into the Z108 case from Kradex in the upper connectors level. The whole thing works and fits very well. Finally - if a wire is screwed in, it stays that way...