bootloader doesnt respond (manually bootloading)

[jbeemster]

Hi there.
I have a ESP32 module including a Lora chip and OLED on it. Made by ttgo.
It all works fine. But I broke the USB connector (most likely not that good soledering) .

I connected another USB-to Serial to RX an TX and that works fine. I see my program running and I am able to put it manually into flashing mode. (By pressing the PRG button (i assume it is connected to GPIO0). The message appears like this:
rsv:0x1 (XOWERON_RESET),boot:0x7 (DOWNLOaD_BOOT(UART0/UQRT1/SDIO_REI_REO_V2))
waiting for download
That seems fine to me.
When I start esptool.py to flash the following message appears:
Connecting........_____....._____....._____....._____....._____....._____....._____....._____....._____....._____
A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header
I am also not able to read the chip_id or something else.

The funny thing is that I do not have GPIO0 as a pinout. Wiki did not help me either.
Is someone able to help me. I need to upload it just once (to continue by Over the air upload)

[Les Atkins]

I had this symptom. I use Linux and with my esp32-Wrover-kit v3 connected via the usb connector the 'ls /dev/tty*' command shows two ports - /dev/ttyUSB0 and /dev/ttyUSB1. I had to set up the menuconfig to use /dev/ttyUSB1 in the 'serial flasher config'. Don't know if this will help you at all.

[ESP_Angus]

Hi jbeemster,

It's hard to guess without knowing the details of the board you have, but is it possible the TX signal from the PC is not getting through to the ESP32? In this case you'll be able to read the boot message (as you have), but esptool.py will fail to make contact.

If there's another onboard USB/serial chip driving the ESP32 RX pin (but not being used) then it's possible this chip is "fighting" your USB/serial adapter when it tries to drive the line.

Angus

[chegewara]

Im having similar symptoms from time to time. Im playing with esp on vbox ubuntu 14, and only unplug device and plug again helps. Sometimes this does not help then i have to turn on manually bootloader mode under windows and then switch to ubuntu and flash app.
In my case it is with devKitC rev1 i guess(black).