transmitted data copied to recv buffer

[sreenath_b]

Hi all,
I am having tough time finding what is going on here. I have modified uart_echo sample to talk to a 4G gsm module.

When I read data from the serial port, all data that was sent to the module using AT commands is read back to receive buffer.
I have used ATE0 command to eliminate the echo from the GSM module. So this seems to be happening in the driver.

I have tested the GSM module using simple USB-UART devices (FTDI and others) and after ATE0 command, no echo is seen, and the serial port reads what was sent from GSM module and not what I sent.

I was able to eliminate this once by increasing stack size, but is still happening now when I have set stack to 16K Bytes,
This is the dual core ESP32 module.

IDF version : ESP-IDF v4.4

thanks for any pointers.
Sreenath