Raspberry Pi Forums

Posted: Sun Nov 09, 2025 12:20 am

by Starnaya

Hello :D ,

I'm making a DIY smartphone and I found a video using the waveshare 4G HAT for the actual "Phone" part of the smartphone but it takes up all of the GPIO pins so I can't connect a touch screen to the Pi. I was thinking of connecting a rapsberry pi 4 with the waveshare HAT to a raspberry pi 3 with a waveshare 14300 5inch touch screen and I'm just wondering if that's possible. I've looked it up on google but I haven't really found much.
I also have almost 0 experience in raspberry pi and just coding in general so maybe I'm just missing something.

This is the article for the 4g HAT: https://core-electronics.com.au/guides/ ... g-gps-hat/

Posted: Sun Nov 09, 2025 10:59 am

by ame

That would not be an expedient solution.

You have two options. One is to get an official touch screen, which doesn't need to connect to GPIO. So you can use your 4G HAT.

The second is to get an alternative 4G device, such as a USB dongle. This will free up the GPIO pins to let you use the other touch screen.

Posted: Sun Nov 09, 2025 11:06 am

by thagrol

It might physically occupy all 40 pins but it probably doesn't use all of them electrically.

Find out what pins that HAT actually uses and what pins your preferred screen uses. Then you'll know whether there is a conflict.

If there isn't a conflict there are many products and DIY soultions for sharing the GPIO header.

Posted: Sun Nov 09, 2025 11:57 am

by rpdom

What thagrol said.

Looking at the link you gave, I can see

- What GPIO Pins are being Utilised by HAT

which sounds like a promising place to start.

Posted: Sun Nov 09, 2025 2:41 pm

by Starnaya

Thanks for the responses! I'll definitely be looking into what you guys said.