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Noise on serial line

Posted: Thu Dec 22, 2022 7:13 pm
by CarbonMan
I am connecting 2 esp32s together, communication is one-way. The sender is a Makerfab esp32uwb based on the WROOM and the receiver is a WT32-SC01 based on the WROVER.

The sender initializes the connection with
  1. Serial1.begin(9600, SERIAL_8N1, RXD1, TXD1);
where TXD1 is 12

The receiver initializes the connection with
  1. Serial1.begin(9600, SERIAL_8N1, RXD1, TXD1);
where RXD1 is 13
Grounds are connected.

The connection works, I can send data. However, there is constant noise on the receiver.
I have tried both
  1. pinMode(RXD1, INPUT_PULLUP);
and
  1. pinMode(RXD1, INPUT_PULLDOWN);
on the receiver, but it makes no difference.

I have tried different pins on the sender and the receiver.
Interestingly this did not happen when I used a different board (it was a DEVKIT V1 DOIT I believe) as the sender.

Edit: I have tried changing the sender and receiver to
  1. SERIAL_7E2
but it didn't help.

Any ideas?

Re: Noise on serial line

Posted: Thu Dec 22, 2022 8:02 pm
by username
How long is the serial cable.

Re: Noise on serial line

Posted: Thu Dec 22, 2022 9:35 pm
by CarbonMan
Very short. Maybe 10cm.