ESP32-WROVER module with 3.3V flash? (or ESP32-WROVER is not ESP32-WROVER-B)

[reinisv]

Preface: after I had written this post, I checked the Espressif website again, and realized that ESP32-WROVER and ESP32-WROVER-B are different products with different datasheets. I had ordered ESP32-WROVER-B and tried to use it on a board designed for ESP32-WROVER. ESP32-WROVER-B does indeed contain 3.3V flash memory.

I'll just leave the post here, in case anyone else faces a similar problem.

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I've designed a PCB for ESP32-WROVER module. According to the https://www.espressif.com/sites/default ... eet_en.pdf datasheet, GPIO12/MTDI should be pulled high internally, as the module is supposed to contain 1.8V flash.


My intention was to re-use this pin as GPIO, and I also pulled the pin up on my board.

However, the communication between ESP32 bootloader stub and flash chip did not work:

Code: Select all

esptool.py v2.6-beta1
Serial port /dev/ttyACM0
Connecting.....
Chip is ESP32D0WDQ5 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, BLK3 partially reserved, Coding Scheme 3/4
MAC: 30:ae:a4:c9:85:0c
Uploading stub...
Running stub...
Stub running...
Manufacturer: ff
Device: ffff
Detected flash size: Unknown
Hard resetting via RTS pin...

Monitoring the serial output, it was seen that MTDI was indeed high during boot:

Code: Select all

rst:0x10 (RTCWDT_RTC_RESET),boot:0x33 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371 
ets Jun  8 2016 00:22:57

I soldered another module to the board with wires, connecting just the bare minimum of the signals: VDD, GND, RX, TX, IO0, EN. This worked- the flash chip is identified:

Code: Select all

esptool.py v2.6-beta1
Serial port /dev/ttyACM0
Connecting......
Chip is ESP32D0WDQ5 (revision 1)
Features: WiFi, BT, Dual Core, 240MHz, VRef calibration in efuse, BLK3 partially reserved, Coding Scheme 3/4
MAC: 30:ae:a4:c5:f6:9c
Uploading stub...
Running stub...
Stub running...
Manufacturer: c8
Device: 4017
Detected flash size: 8MB
Hard resetting via RTS pin...

Monitor shows that the MTDI pin is low now:

Code: Select all

rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
flash read err, 1000
ets_main.c 371 
ets Jun  8 2016 00:22:57

The datasheet shows, that the R9 is pull-up for the GPIO12 pin. I cracked open one of the modules, and the R9 is not populated.



Am I missing something (perhaps, I'm using an old datasheet?)

[ralf.8070]

You've made my day
Thanks for this great finding.
We've made the same mistake.

Ralf