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Serial Communication Issue

Posted: Wed Nov 18, 2020 5:29 am
by rajendran20
I have a circuit that uses 2 serial UART connections from ESP32 WROOM to 2 Chipsets (Quectel L96 -GPS and Quectel BC66 - nBIOT).
L96 TX is connected to ESP32 pin 5 (RX) whereas BC66 TX and RX and connected to ESP32 pin 16 and 17. They are configured as follows

Serial1.begin(9600, SERIAL_8N1, 5, 18);
Serial2.begin(115200, SERIAL_8N1, 16, 17);

L96 uses Serial1 (to receive GPGGA data)
BC66 uses Serial2 (to send AT commands to send GPS data after processing by ESP2)

The issue is, when both serial ports are open, I have a problem. No GPS data is received but sending AT commands via Serial2 is ok. When i comment off AT commands for the nBIOT part, GPS is then able to receive. I have used individual programs (one for GPS using Serial1 and one for nBIOT using Serial2) and both of them work on their own

The problem occurs when both are being used at the same time.

Any help on this will be helpful. Thanks