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UART Communication between GSM and GPS

AAnkur

New Member
UART Communication between GSM and GPS

I want to establish a UART Communication between GSM and GPS.
The Supply Voltage of GPS is 3.3V.
The Supply Voltage of GSM is 3.8V.

The measured RX/TX Voltage Levels of GPS is 2.8V and 0V (for logic High and logic Low).
The measured RX/TX Voltage Levels of GSM is 1.8V and 0V (for logic High and logic Low).

Since there is a difference between RX/TX logic levels of the GSM and GPS, So I am
not able to establish the UART Communication between GSM and GPS.

Please suggest me a possible way to perform voltage (or Logic) level shifting.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
A simple resistive divider to drop the 2.8V down to 1.8V (1K resistor and 1.8K for example) is all that's needed, the 1.8V up to 2.8V isn't a problem, as it should fall within the permitted range.

Or you can get specific level shifting boards, they use resistors as above downwards, and an FET upwards.

However, I fail to see what you're trying to do?, you need a micro-controller between them to process the data and instructions to both boards.
 

AAnkur

New Member
Thanks for your reply.....

I am using the interpreter present in the telit GSM module to process the inputs of the GPS. I am not using any micro-controller in between the GSM and GPS.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Thanks for your reply.....

I am using the interpreter present in the telit GSM module to process the inputs of the GPS. I am not using any micro-controller in between the GSM and GPS.
I wasn't aware they were programmable to that degree?, but if they are it makes things easier.
 

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