I'm trying to flash a Wemos D1 mini ESP8266 board with the blink sketch, but get an error. The built in LED turns off when flashing starts.

Sketch uses 247872 bytes (23%) of program storage space. Maximum is 1044464 bytes.
Global variables use 28000 bytes (34%) of dynamic memory, leaving 53920 bytes for local variables. Maximum is 81920 bytes.
warning: serialport_set_baudrate: baud rate 921600 may not work
warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
error: espcomm_upload_mem failed

I tried changing the programming speed to most of the other options.

If I open the serial monitor and set the baud rate to 74880, I get the following message repeatedly.

Fatal exception (0): 
epc1=0x400cd530, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000

Is the board dead, or is there a way of reflashing it without using the serial port?

  • How are you powering the board?
    – Majenko
    Nov 28 '18 at 23:33
  • warning: serialport_set_baudrate: baud rate 921600 may not work try a lower baudrate (115200 is safe) because your code isn't uploading error: espcomm_upload_mem failed - perhaps you got a partial upload at some time which is causing the fatal exception on boot - Nov 29 '18 at 1:01

Flashing with the serial port is the only practical option. The flash chip can be removed, and it can be flashed off board, but that isn't practical.

Has the board ever worked? Have you used other RSP8266 boards before or is this the first you have? Do you have a different USB cable you can try? Marginal power can cause unpredictable operation.

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