Hello, I was hoping to ask the community for if they have any ideas for ways to give the turing pi 2 more GPIO. I haven't received mine yet, but more wondering for after I do receive it. I planned to have at least two of my pis dedicated to gpio for a total of 80 GPIO pins, but I somehow didn't notice this until recently, the turing pi will only have 1 GPIO header. I've seen a couple of pcie GPIO options, but I don't know how well those will work with a pi. I've also though of getting a couple of raspberry pi picos, and using my 1 GPIO header to communicate with those, and then having those handle most of the actual GPIO, but I know that would limit my bandwidth, but at least it would give me more physical pins. If anyone has any suggestions let me know.

Hi

Well that's a bit disappointing, but thank you. I mean I still have 2 raspberry pi 4s (not compute module) if I really need dedicated pi gpio, was just hoping to combine everything into the turing pi 2, although I do mostly need just physical pins, so hopefully I can get by with using pi picos communicating back to one of the compute modules on the turing pi

They should work, yes. I don't know what are you going to use the GPIO for, but simple SPI to parallel chips like 74HC595 might be more than you need, and you can cascade them

Thank you for the suggestions!

So I think that the 74HC595 and similar will be more than you need. these are serial to parallel interfaces that you can cascade but they also has latches. What this means you can connect many of them, push states to them in a serial fashion (a series of 1s and 0s) and latch the values once updated

Alright, thank you for your help, I can't implement any of this yet as I don't have my TPi2, but thank you for your advice, At least while I wait I can do more research. Thank you again for your help and advice!

Yeah, read about 74HC595 probably and feel free to ask more questions if you have any 🙂

I wish that they would have exposed most of the pins on the adapter board. Then every slot would have GPIO pins but on the adapter board. Slot 1 would be a little complicated to have GPIO pins when not using a CM4 though.

Yegh having the gpio on the adapter board would be nice so every pi can have gpio and not pis won't be affected, but I imagine then you might run into issues with gpio hats putting to much weight on the adapter boards, but I could be wrong

The specs state the GPIO to be as a normal PI so I would assume to be able to use it with a CM4 in slot 1 as usual. However I came along the section “Please note that there are 2 differences compared to the Raspberry Pi and the Nvidia Jetson header pinouts…” and now it reads as not to be fully useable as a commit PI GPIO. Can this point be pls. clarified. Thx.

There are 2 differences. One is minor - the UART is not connected there, the other is major - one pin is GND instead of -3V3 and you'll need to modify your hat or cable

Well, what you refer to be minor is kn fact a major issue to me since I would have wanted to use a HM-MOD-RPI-PCB which communicates via UART with the PI.

By minor I meant it does not prevent things from working (except for these which use UART). The other incompatibility is major since it prevents hats from working. As for lack of UART - by TPi2 design, UART is connected to BMC and CM4 does not provide additional UARTs

Is there a way of stacking the cm4 to the tp2 board and having a breakout in between to overcome this?

What do you mean by stacking the CM4 to the TPi2?

I mean, the CMs have a cartridge for plugging into the TP2. Isn’t there anything to put in between? That way one could also use the original GPIO per each, right?

There are no other adapter boards that route the UART differently