Waveshare 4G HAT for Raspberry Pi (LTE Cat-4/4G/3G/2G/GNSS) (CE07826)

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Enable LTE Cat-4 4G/3G/2G communication and GNSS Positioning for your Raspberry Pi

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Can you use the waveshare 4g hat with a raspberry pi 3 model A+

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Welcome Mick!

You definitely can - this HAT uses the same 40-pin Raspberry Pi header that all modern Pi’s do.



I’d love to try this. Before, I only used SIM900A to make this kind of projects: Sending SMS & Call with GSM Module and Raspberry Pi 4 - The Engineering Projects
But SIM900A is not 4G supported. Good to see that we have 4G enabled HATs now.

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Hi. I was wondering if this HAT would work on an older Raspberry Pi 2 Model B (v1.1). It already has a LM75 thermometer mounted on the GPIO or is there some other way to attach it rather than through the GPIO (USB?) and still be able to script calls to send SMS (assuming through an API or AT commands). I too would like to use something like this on an existing Pi to make better use of it. Any advice would be appreciated.

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Hi Bruce,

Welcome to the forum :slight_smile:

As far as pin compatibility goes that HAT should be fine with a RPi 2B.
You should be able to stack the LM75 thermometer on top of the 4G HAT since it has stacking GPIO headers fitted. You will just need to check there isn’t a collision between the GPIO pins in use by the 4G HAT. The pinout for the 4G HAT below shows the key pins you’ll need to keep free.

Thanks heaps for this. I will check the pins for the LM75 but I guess the Power and Ground would be good candidates for a collision. When stacked is it common for things to share power and ground?

Again thanks for your help

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Hi Bruce,

That’s a great question, I simplified things a bit in my first answer.
You will want all devices to share a common ground connection, sharing a power rail is also fine provided the total power consumption of the devices is within what your power supply can output.
If you have devices that are using a communications bus like I2C or SPI, those pins can also be shared between devices so long as each device has a different address.

The big risk with stacking devices on a Raspberry Pi will be running out of power or having digital input or output pins that two devices are trying to control exclusively.

Thanks again.

Based on what I can see from the physical LM75. I think there will be a collision on Pins 7 & 9. 9 being a ground maybe ok. But 7 seems to be some type of Flight Mode toggle. According to your diagram it can be ‘enabled’ with a jumper so I am assuming it can be disabled without a Jumper. Which again with my limited knowledge would mean the pin wouldn’t carry any signal and thus could be used by the LM75 sitting on top of it? Or is that just pure rubbish from a novice?


This isn’t my board with a LM75 but it does match the position of the LM75 on my board.

Hi Bruce,

You won’t be able to use Pin 7 for another device without interfering with the operation of the 4G HAT.
There is some more info on how the HAT works on the manufacturer’s wiki page.
This graphic in particular explains what is going on. The Raspberry Pi is using D4 to indicate the status of Flightmode to the HAT. If the jumper is disconnected then the signal won’t get through to the HAT and the flight mode control will be disabled but that won’t leave the pin free for use by the LM75 since the Pi is still trying to use it to talk to the HAT

Thanks Trent so seems another Pi might be needed.

Really appreciate your time and help

Will this work with the Raspberry Pi Zero WH 2 model?