Hy
I would like to ask you for a bit of help. We are trying to build a fleet management system. As a GSM module we use SIM800L
We only need the GSM Module for Data Transfer, so we tested with RP3.
The problem is that it is very hectic/rare, sometimes it connects to the network sometimes it does not.
It is working very strange. My biggest problem is that it is giving me frequently the following message:
„SMS READY”
„CALL READY”
Why is it doing this?
We plugged/set it up as follow:
SIM800L - Rpi
vcc -> 5V
GND -> GND
RX/TX -> Tx/Rx
We tried to separate the power supply of VCC and GND both from a different power by 4,2 V, but the outcome is the same.
Interesting that if we do not plug them directly to RX/TX pins, instead of this we use a cable and connect to the USB port it works perfectly.
https://www.robotshop.com/en/usb-to-ttl-serial-cable-debug-console-cable-raspberry-pi.html
Why do we experience this? What is the reason of this? How should we connect them to each other? Thank you very much for your help in advance