Posts: 7
Joined: Sat May 11, 2013 10:33 pm

GPIO - Cobbler pinouts

Mon Nov 28, 2016 3:42 am

Okay, so I've had a PiB that I played with a little 4 or so years ago, I added a pi 2B about a year ago, then just recently acquired a Pi3B. Initially I was intrigued by the software, but am looking to experiment with IOT, so having both a PiB (v2, I think) with 26 pin GPIO and a 2B and 3B with 40 pin GPIO how do I make since of differences in pinouts? I bought a 40 pin T-Cobbler for the 2B and 3B and then last week a 26 pin T-Cobbler for the 1B the major difference between the two from my perspective is that the Viaboot plugs into a breadboard on a 2X20 matrix, the 26 pin T-Cobbler splits power and GND off onto the 'T' with 3.3V + GND on one side and 5V + GND on the other in the power columns of the breadboard, then there are only 2X9 pins connected down the breadboard! Looking at the projects on and elsewhere, either physical pinouts are quoted, 1-26 or 1-40 or the slightly more cryptic but probably more meaningful GPIO numbering scheme, which I don't fully understand as yet but seems easy to follow except for my cobblers! does anyone have a way I can 'map' the two, without sitting down and doing it with a multimeter? Is anyone familiar with the products? The 40 pin t-Cobbler or the seemingly generic 26 pin I have too? (see attached photo), Any help would be much appreciated.

User avatar
Posts: 19543
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: GPIO - Cobbler pinouts

Mon Nov 28, 2016 6:57 am

The part of the cobblers that plugs into the breadboard should have the GPIO numbers printed on it. You don't need all of the pins, as many on the 26 and 40 way connectors are GND pins and your really only need one on your breadboard. The same goes for the two 3V3 and 5V pins. is a good site for looking at the different naming conventions of each pin and what they can be configured to do.

User avatar
Posts: 5534
Joined: Sun Dec 28, 2014 3:02 pm
Location: East Yorkshire

Re: GPIO - Cobbler pinouts

Mon Nov 28, 2016 7:29 am

There is no attached photo, but I have two different 'full pin' call it a + model as the 40pin is based on the B+ design iirc.

One like your shorter has the 3V3 and 5V placed directly into the power rails, very convenient and my favourite design. Saves a few wires.

The link given is great to use.
GPIO / BOARD pinout usually refers to physical pin number.
BCM (Broadcom) refers to actual pin function. RaspberryPi foundation and anything designed by them used BCM.

BCM is the most useful for knowing what's what and not using a pin that may be useful for something else.

GPIO pin counting is so much easier for the young to setup and use and teach with. It's good to give a nod to BCM after a bit and explain, just to use both, count the pins but take not of the BCM naming so they see and can use both (avoiding 3V3's and GND is often a good skill to get into ;-))

A breakout makes it easier as it's all written out for them.
I assume yours have numbering on them, so learn them both.

You can ignore the later GPIO pins if you wish to make them compatible between the Pi's

Return to “Interfacing (DSI, CSI, I2C, etc.)”