Arduino won't boot with serial Rx connected to Wemos Tx

Using Arduino IDE 1.x
1

Howdy all,

I have an Arduino Mega 2560 connected via serial to a Wemos D1 mini (Rx from the Mega to Tx of the Wemos and Tx from the Mega to Rx on the Wemos).

It all works great comms wise, except I can't start the arduino with the Arduino's Rx line connected.

As soon as I unplug the Rx line, I can start up without issue, plug the Rx line back in and it merrily receives data from the Wemos as normal.

Any thoughts would be greatly appreciated - it's a bit of a showstopper for my project, so I'm very keen to resolve the issue.

Regards,

Doug.

2

(deleted)

3

If by "start" you mean program or do any sort of interaction over usb this is correct and expected behavior, as you have connected something else to the pin used for communication between the on-board usb serial adapter and the microcontroller.

As noted above, the solution is to use one of the other three serial ports (Serial1~Serial3), which are also on different pins