ESP32-WROVER randomly goes into download mode (ROM serial bootloader for esptool.py)

karlito
Posts: 2
Joined: Wed Mar 28, 2018 8:48 am

ESP32-WROVER randomly goes into download mode (ROM serial bootloader for esptool.py)

Postby karlito » Wed Mar 28, 2018 9:13 am

Once in a while (2-3% of the time), the ESP32-WROVER will go into download mode even when GPIO0 is high. This happens after power cycling. We get the message below and we don't know what “boot:0x20” exactly means. We couldn’t find any useful documentation on the first stage bootloader.

Entire boot message:
rst:0x1 (POWERON_RESET),boot:0x20 (DOWNLOAD_BOOT(UART0/UART1/SDIO_FEI_FEO_V2))
waiting for download

For comparison purposes, when we actually want to enter download mode by setting GPIO0 low, the boot message is:

rst:0x1 (POWERON_RESET),boot:0x23 (DOWNLOAD_BOOT(UART0/UART1/SDIO_REI_REO_V2))
waiting for download

Thanks in advance.

WiFive
Posts: 3529
Joined: Tue Dec 01, 2015 7:35 am

Re: ESP32-WROVER randomly goes into download mode (ROM serial bootloader for esptool.py)

Postby WiFive » Wed Mar 28, 2018 7:55 pm

GPIO strapping results: Bit5-bit0 of boot_sel_chip[5:0] correspond to MTDI, GPIO0, GPIO2, GPIO4, MTDO, GPIO5, respectively.

So 0x20 is showing gpio0 as low

ESP_Angus
Posts: 2344
Joined: Sun May 08, 2016 4:11 am

Re: ESP32-WROVER randomly goes into download mode (ROM serial bootloader for esptool.py)

Postby ESP_Angus » Thu Mar 29, 2018 3:02 am

Hi Karlito,

Is your WROVER on a custom board? Does GPIO0 have any external pullup or other external connection? Is it possible the rise time of the GPIO0 pullup is slower than the rise time of the ESP32-WROVER's VCC?

Thanks,

Angus

karlito
Posts: 2
Joined: Wed Mar 28, 2018 8:48 am

Re: ESP32-WROVER randomly goes into download mode (ROM serial bootloader for esptool.py)

Postby karlito » Fri Apr 06, 2018 10:24 am

Thanks for the answers.

It is a WROVER custom board. We used an external pullup resistor and we removed it. It seems to fix the issue since it never happens again after that.

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