I bought a couple of ESP32CAMs from aliexpress... althought the listing shows them with two buttons, I got the ESP32-CAM-MB boards with just the reset button...

I have my computer set up to dual boot Windows and Linux so when I got an error in windows, I rebooted and installed the ESP32 boards for Arduino 2.1 and went ahead. I had to also install esptool and pyserial for it to work, but it ended up recognizing the port and every time I try to program it the flash flashes, but the programmer responds with

A fatal error occurred: Failed to connect to ESP32: Wrong boot mode detected (0xb)! The chip needs to be in download mode.

When I enable the serial console and press the reset button I get the following:

ets Jul 29 2019 12:21:46

configsip: 0, SPIWP:0xee
mode:DIO, clock div:2
ho 0 tail 12 room 4
entry 0x40080688
[0;32mI (31) boot: ESP-IDF v4.1-dirty 2nd stage bootloader[0m
[0;32mI (31) boot: compile time 16:15:01[0m
[0;32mI (31) boot: chip revision: 3[0m
[0;32mI (34) boot_comm: chip revision: 3, min. bootloader chip revision: 0[0m
[0;32mI (41) boot.esp32: SPI Speed      : 40MHz[0m
[0;32mI (46) boot.esp32: SPI Mode       : DIO[0m
[0;32mI (51) boot.esp32: SPI Flash Size : 4MB[0m
[0;32mI (55) boot: Enabling RNG early entropy source...[0m
[0;32mI (60) boot: Partition Table:[0m
[0;32mI (64) boot: ## Label            Usage          Type ST Offset   Length[0m
[0;32mI (71) boot:  0 nvs              WiFi data        01 02 00009000 00005000[0m
[0;32mI (79) boot:  1 otadata          OTA data         01 00 0000e000 00002000[0m
[0;32mI (86) boot:  2 app0             OTA app          00 10 00010000 00300000[0m
[0;32mI (94) boot:  3 spiffs           Unknown data     01 82 00310000 000f0000[0m
[0;32mI (101) boot: End of partition table[0m
[0;32mI (106) boot_comm: chip revision: 3, min. application chip revision: 0[0m
[0;32mI (113) esp_image: segment 0: paddr=0x00010020 vaddr=0x3f400020 size=0x1d2048 (1908808) map[0m
[0;32mI (849) esp_image: segment 1: paddr=0x001e2070 vaddr=0x3ffbdb60 size=0x04d3c ( 19772) load[0m
[0;32mI (857) esp_image: segment 2: paddr=0x001e6db4 vaddr=0x40080000 size=0x00400 (  1024) load[0m
[0;32mI (858) esp_image: segment 3: paddr=0x001e71bc vaddr=0x40080400 size=0x08e54 ( 36436) load[0m
[0;32mI (880) esp_image: segment 4: paddr=0x001f0018 vaddr=0x400d0018 size=0x9df74 (647028) map[0m
[0;32mI (1127) esp_image: segment 5: paddr=0x0028df94 vaddr=0x40089254 size=0x0b6a0 ( 46752) load[0m
[0;32mI (1159) boot: Loaded app from partition at offset 0x10000[0m
[0;32mI (1159) boot: Disabling RNG early entropy source...[0m
SD Size: 29557MB  OK

I can see that the board is in SPI_FAST_FLASH_BOOT mode which according to the linked documentation is wrong... but how to I get it to reboot in the correct mode?

Others have had similar issues, but they use another tool stack, so I am not sure what their solution would translate to in the Arduino 2.1 IDE...

stacked bottoms tops

1 Answer 1


While making sure I included all the correct links and pictures in the question, I found the answer - if an SD card is inserted, the flashing cannot be performed.

Removing the SD card and resetting the ESP32 works. I now have a very bright flashing LED

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