ESP32 Forum

Posted: **Mon Feb 04, 2019 11:50 am**

Hello,

I have a ESP32 WROOM and it worked fine for a while. Now I am unable to make connection with it, but I still see it as CPOM8.

I tried this:

Code: Select all

PS E:\Dropbox\ZEsp32> python -m esptool --port COM8 erase_flash
esptool.py v2.5.0
Serial port COM8
Connecting........_____....._____....._____....._____....._____....._____....._____

A fatal error occurred: Failed to connect to Espressif device: Invalid head of packet (0x00)

which used to work before. I also pressed the right hand button while issuing the command, whicn in the past has enabled flashing, but this doesn't help now.

Is it bricked, or can I do something to flash it again?

Many thanks!

Posted: **Mon Feb 04, 2019 1:06 pm**

One way to troubleshoot this is to open the serial port with a terminal program, and see what message you get when you hold "boot" button and press "reset" button. If it is not "waiting for download" then the bootloader is not in the correct boot mode. If you don't get any message, then the COM port is not the right one, or there is an issue with the module.

Posted: **Mon Feb 04, 2019 1:08 pm**

Thanks for this - when I try this, all I get is the PuTTY showing a blank screen with the cursor at the top left. No combination of the buttons seems to do anything.

Posted: **Mon Feb 04, 2019 1:14 pm**

If you are sure that the COM port is the right one (e.g. it disappears when you disconnect the board from USB) then the only remaining option is a hardware issue with the board. If you have got a spare USB-UART adapter, you may try connecting it to TXD/RXD pins of the board and see if you get any output through it. If you do, then the USB-UART on the original board is not working. If you don't, then likely the ESP32 chip has been damaged.

Posted: **Mon Feb 04, 2019 1:16 pm**

Yes, it does go away when I pull the USB out. I don't have a UART coupler, so it priobably remains for me to discard the circuit. Thank you for helping my troubleshooting.

ESP32 Forum

Unable to flash, even if I see the device as COM8

Unable to flash, even if I see the device as COM8

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Re: Unable to flash, even if I see the device as COM8

Re: Unable to flash, even if I see the device as COM8