ESP8266 Community Forum

- Sat Dec 22, 2018 10:42 am #79683 What I've been doing may be wrong etc, but I'm new to this and have been chucking every suggestion I've read at these boards.

I have 5 NodeMcu v3 boards, 3 work fine, 2 are playing up.

If I try and upload a sketch to the dud ones it gives me a

Code: Select allwarning: espcomm_sync failed

So after reading lots of suggestions I've now managed to flash the firmware by doing the following

I've connected GPIO0 & GPIO15 to ground and the Serial out reads

Code: Select allets Jan  8 2013,rst cause:2, boot mode:(5,6)

This will now let me flash the firmware and serial reads

Code: Select allets Jan 8 2013,rst cause:2, boot mode:(1,7)

I then hit the Reset button and Flash the Sketch which now uploads fine. And the program runs.

However if I reset with pins 0 & 15 connected the board won't boot.

If I disconnect GPIO0 and leave GPIO15 Pulled low the serial output reads

Code: Select allets Jan  8 2013,rst cause:2, boot mode:(3,7)

And hitting the reset button will now boot the board and run.

It seems GPIO15 is stuck high and I cant find anyway of booting Low. I've cleaned the traces to get rid of any flux etc.

Checking the boards which work without any issue, they boot with a serial output of

Code: Select allets Jan  8 2013,rst cause:2, boot mode:(3,7)

This is the same as the iffy boards if GPIO15 is manually pulled low.

Any thoughts?