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5 posts • Page 1 of 1
Starnaya
Posts: 2
Joined: Sat Nov 08, 2025 11:53 pm

Connecting Two Raspberry Pi's together

Sun Nov 09, 2025 12:20 am

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/

ame
Posts: 11565
Joined: Sat Aug 18, 2012 1:21 am

Re: Connecting Two Raspberry Pi's together

Sun Nov 09, 2025 10:59 am

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.
Oh no, not again.

thagrol
Posts: 14790
Joined: Fri Jan 13, 2012 4:41 pm

Re: Connecting Two Raspberry Pi's together

Sun Nov 09, 2025 11:06 am

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.
Knowledge, skills, & experience have value. If you expect to profit from someone's you should expect to pay for them.

All advice given is based on my experience. it worked for me, it may not work for you.
Need help? https://github.com/thagrol/Guides

rpdom
Posts: 25256
Joined: Sun May 06, 2012 5:17 am

Re: Connecting Two Raspberry Pi's together

Sun Nov 09, 2025 11:57 am

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.
Unreadable squiggle

Starnaya
Posts: 2
Joined: Sat Nov 08, 2025 11:53 pm

Re: Connecting Two Raspberry Pi's together

Sun Nov 09, 2025 2:41 pm

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

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