From the elinux.org documentation for this GPIO, I have summarized the following information:

The Raspberry Pi Model A+ and B+ boards, and the Pi 2 Model B, have a 40-pin 2.54 mm header marked J8, arranged as 2x20 pins. GPIO voltage levels are 3.3 V and are not 5 V tolerant. There is no over-voltage protection on the board - the intention is that people interested in serious interfacing will use an external board with buffers, level conversion and analog I/O rather than soldering directly onto the main board.

The header looks like this:

enter image description here

What I would like to do is create a breakout panel that provides, primarily, easy to access and labelled jumper lead sockets for the GPIO lines from the header on the Pi board. I would like to add over-voltage protection for 3.3V, and also possibly an LED for each line to indicate it's high or low status.

I haven't been active in electronics for a long time, so I would like to know what the ideal socket type would be, as opposed to large and clumsy olden day "banana plugs", and then how to provide over-voltage protection. The sockets should be further spaced and much harder to incorrectly select than the fine spacing on a breadboard based breakout.

One of the first and simplest experiments with the Pi is powering an LED, with resistor, directly connected to a ground and output pin on the GPIO header. If possible, I would like to include such an LED for each GPIO line on my breakout panel, but can I do this without affecting the normal function of that line with whatever circuit it is actually used to communicate with.

  • \$\begingroup\$ 'ideal' depends on your situation. What would you want to connect to? For breadboard wires, 'wire cups' spaced 2.54 mm apart (in a single row) are ideal. But if you want to connect thick wires to a screw terminal you would need a quite different spacing. \$\endgroup\$ – Wouter van Ooijen Sep 20 '15 at 9:21
  • \$\begingroup\$ @WoutervanOoijen I think maybe wire cups will be a good choice. I can mount them on a pre-labelled PCB or something like that. \$\endgroup\$ – ProfK Sep 20 '15 at 13:34

You definitely don't want to have an LED pre-wired to every GPIO pin, since it would like interfere with future use of those pins.

Rather than try to build your own, which is going to be a lot of work, take a couple of weeks just to get boards made, and be costly -- since making just a couple of PCB's is always expensive -- I suggest looking into solutions already available such as this one using a cable connected to a breadboard:

enter image description here

or this one using a cape type board, both made by Adafruit.

enter image description here

  • \$\begingroup\$ Adafruit have some very nice looking 'Cobblers', thanks for the reference. Not quite what I want, but may be useful in many other scenarios. I guess I'll have to hack up a UI control that I can place anywhere on a screen to show me the states of all GPIO lines. \$\endgroup\$ – ProfK Sep 20 '15 at 13:30

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.