Boot loop after flashing ESP32-WROOM-32

All ESP32 boards running MicroPython.
Target audience: MicroPython users with an ESP32 board.
Post Reply
cybersword
Posts: 1
Joined: Sun Sep 01, 2019 8:29 am

Boot loop after flashing ESP32-WROOM-32

Post by cybersword » Sun Sep 01, 2019 8:50 am

I've tried flashing with both esp32-20190529-v1.11.bin and esp32-20190901-v1.11-265-g12f13ee63.bin with the same results. The board keeps resetting and i get the following output on the serial console:

rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:2
load:0x3fff0018,len:4
load:0x3fff001c,len:4928
ho 0 tail 12 room 4
load:0x40078000,len:9404
load:0x40080400,len:6228
entry 0x400806ec
.[0;31mE (70) boot: Chip CPU frequency rated for 160MHz. Modify CPU frequency in menuconfig.[0m
ets Jun 8 2016 00:22:57

I guess the clue is in the warning during flashing:

esptool.py --chip esp32 --port /dev/tty.SLAB_USBtoUART write_flash -z 0x1000 Downloads/esp32-20190901-v1.11-265-g12f13ee63.bin --verify ~ mmiedem-nld-mbp
esptool.py v2.7
Serial port /dev/tty.SLAB_USBtoUART
Connecting........___
Chip is ESP32D0WDQ6 (revision 1)
Features: WiFi, BT, Dual Core, 160MHz, VRef calibration in efuse, Coding Scheme None
WARNING: Detected crystal freq 41.01MHz is quite different to normalized freq 40MHz. Unsupported crystal in use?
Crystal is 40MHz
MAC: 80:7d:3a:c7:53:48
Uploading stub...
Running stub...
Stub running...
Configuring flash size...
Auto-detected Flash size: 4MB
Compressed 1204352 bytes to 756178...
Wrote 1204352 bytes (756178 compressed) at 0x00001000 in 67.2 seconds (effective 143.3 kbit/s)...
Hash of data verified.

Leaving...
Verifying just-written flash...
(This option is deprecated, flash contents are now always read back after flashing.)
Verifying 0x126080 (1204352) bytes @ 0x00001000 in flash against Downloads/esp32-20190901-v1.11-265-g12f13ee63.bin...
-- verify OK (digest matched)
Hard resetting via RTS pin...

Here's a picture of my board: https://imgur.com/a/zN63Nvn (Cheap clone from China)

Anything that I'm missing or is it really a bad crystal?

User avatar
Roberthh
Posts: 1572
Joined: Sat May 09, 2015 4:13 pm
Location: Rhineland, Europe

Re: Boot loop after flashing ESP32-WROOM-32

Post by Roberthh » Sun Sep 01, 2019 6:37 pm

The strange thing is, that the crystal is in the ESP32 Wroom module. So either the WROOM module is defective, or it is bad manufactured clone. None of my device here have this 160MHz message.

OutoftheBOTS_
Posts: 642
Joined: Mon Nov 20, 2017 10:18 am

Re: Boot loop after flashing ESP32-WROOM-32

Post by OutoftheBOTS_ » Sun Sep 01, 2019 8:22 pm

I have had a rebooting problem like this before caused by there not being enough capacitance on the EN pin.

Looking at the pic of your board and the pinout for the Wroom module it is not possible they have a 100nf cap attached as close as possible to the EN pin.

User avatar
ghayne
Posts: 15
Joined: Sat Jun 08, 2019 9:31 am
Location: Cwmllynfell, Wales

Re: Boot loop after flashing ESP32-WROOM-32USB C

Post by ghayne » Fri Sep 06, 2019 3:02 pm

Are you maybe using an underpowered USB(from a laptop etc). I have a very similar module that reboots frequently if I power it from a normal USB on my laptop but if I use the USB C (with an adapter) it works fine. It might not be getting enough power. The voltage regulator on the board is fine by the looks of it, something that is not always given. I have some cheap ESP8266 boards with low spec regulators.

This link might be usefull as I suspect ist applies to some cheap ESP32 boards too.

https://www.reddit.com/r/esp8266/commen ... 150ma_33v/

Post Reply