Wemos D1 Mini won't start with D3 grounded, other D pins fine

Development Tools IDE 1.x
1

Hi all,

Has anyone seen this? I have a simple sketch that prints "setup" to serial during setup() and "loop" during loop(), and then delays for 2000 milliseconds.

When I have any single digital pin grounded EXCEPT D3, the board works fine and prints a bit of serial garbage then "setup" followed by "loop" repeatedly.

However, with D3 grounded, I get some serial garbage, then nothing. The sketch does not start.

This occurs regardless of any pinMode command (I don't believe it even hits the pinMode as it doesn't even print "setup" as per the sketch.)

Thoughts?
Thanks,
Scott

2

Follow-up: it seems I need to read this:

https://www.forward.com.au/pfod/ESP8266/GPIOpins/index.html

3

D3 is io 0 a boot configuration pin which should be HIGH for normal boot and LOW to start bootloader flashing mode