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MSP430FR5969 interfacing with a gsm sim800l

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I am trying to interface my MSP430FR5969 with a sim800l gsm. The following AT commands are sent to the gsm through the Serial1 UART (the responses are in blue):










The response i expect for AT+CBC is the strength of the battery in the format: +CBC: 0,00,0000 where the zeroes are replaced with the data. The AT+COPS? command should return a long string.

It seems to me that not all of the message is making it from the gsm module. I found this exert for the arduino board on a guide for this gsm:




If your message is long enough just like ours, then you’ll probably receive it with some missing characters. This is not because of a faulty code. Your SoftwareSerial receive buffer is getting filled up and discarding characters. You are not reading fast enough from the buffer.

The simplest solution to this is to increase the size of the SoftwareSerial buffer from its default size of 64 bytes to 256 bytes (or smaller, depending on what works for you).

On a Windows PC, go to C:\Program Files (x86) -> Arduino -> hardware -> Arduino -> avr -> libraries -> SoftwareSerial (-> src for newer version of Arduino IDE) Open SoftwareSerial.h and change the line:



Could this issue also apply to the MSP430? If so then how could I increase the size of the serial1? Or am i thinking this wrong? Any  help is appreciated.


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The FR5969 use a hardware serial interface and the buffer size is set to 16 byte here.

Do do not think that this would be the issues as while data coming in also data a take out of the buffer from the software.

Of course you can give it a try with a bigger buffer - just check the HardwareSerial.cpp file.

Note: take the one in the Energia update directory: e.g. for windows


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