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Connect ESP32 with SIM7000E NB-IoT HAT

JGLJGL

New Member
Hello, I have the following issue to connect this two shields:
The ESP32 works at 3,3v, while SIM7000 works at 5v.
How could I connect both of them without using an external voltage regulator?
 

Pommie

Well-Known Member
Most Helpful Member
Assuming the SIM700 supports I2C then connect ground, the two I2C lines and use pullups to the 3.3V supply. Does the ESP board have 5V in and a 3.3V regulator built in?

Mike.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
According to the schematic on Github the shield contains a level shifter, preset by a jumper to 5V - but including two jumpers you can cut/solder so you can very easily make it 3.3V compatible.

So no issue at all, simply check the documentation.
 

JGLJGL

New Member
First of all, sorry for the delay, as I could not answer before.

I'm using the SIM7000X NB-IoT HAT and the ESP32 module is a custom one.
Pmmie, I see the module has 3,3v pin and 5v pin, so now I'm in doubt if it can also work at 5v.
On the other hand, answering to Nigel, I assume the level Shifter you mention is the one shown in the picture below.

IMG_20191210_091458 (1).jpg

I greatly appreciate your answers as I am lost in this topic,
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Well you confused the situation by saying it was a 'shield' (which is an Arduino board), but the documentation for your Raspberry PI board clearly says:

Onboard voltage translator, 3.3V by default, allows to be switched to 5V via 0Ω resistor
 

JGLJGL

New Member
Ok, so that said, it wouldn't matter if I connect both with 5v or 3,3 v, as it is supposed they both can work with 5v or 3.3v, isn't it ?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Ok, so that said, it wouldn't matter if I connect both with 5v or 3,3 v, as it is supposed they both can work with 5v or 3.3v, isn't it ?
Both the ESP32 and the SIM7000 are 3.3V, so must use that - while their external power might be 5V they have regulators on board to drop it to 3.3V, but you must make sure the SIM is configured for 3.3V which is the default anyway.
 

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