ESP32-S3 - Arduino framework - WIFI credentials not saved ("wrong" bootloader fixes the issue?)

Hi all,

I am trying to migrate an existing app from ESP32 to ESP32-S3. Specifically, I am using:

• device: ESP32-S3-DevKitC-1-N8
• Platform.io Core 6.1.3
• platform-espressif32 version 5.0.0 (i.e. platform = https://github.com/platformio/platform-espressif32.git); also reproducible with 4.4.0 (platform = espressif32)

The Arduino IDE (v 1.8.19) and arduino-esp32 (v2.0.3) were also used to debug this, for reasons that will be clear below.

TL;DR:

My app makes use of WifiProv for provisioning. After migrating to the ESP32-S3, provisioning through BLE “works”, but seems to no longer save wifi credentials to the device, making it useless.

I was able to “fix” this by doing something that sounds like nonsense (but is what the Arduino IDE does?): a manual upload with esptool.py that uses flash_mode set to DIO but uploads the QIO bootloader. That makes no sense to me, and obviously isn’t what happens when using normal Platform.io upload commands.

Investigation notes:

I have created a minimal reproduction repo here. This is basically the WifiProv example, ported to Platform.io, with a tiny change to enable BLE provisioning instead of SoftAP provisioning.

I used the Arduino IDE as a point of comparison / reference. Turns out, if I upload my code from there, everything works!

This suggests the isssue is not with my firmware but with some settings. Using the Verbose Upload command in Platform.io and Process Explorer, I captured the esptool.py commands used by the Arduino IDE and Platform.io.

Arduino IDE:

esptool.py --chip esp32s3 --port "COM4" --baud 921600 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size 4MB \
0x0 C:\Users\nicol\AppData\Local\Temp\arduino_build_174251/WiFiProv.ino.bootloader.bin \
0x8000 C:\Users\nicol\AppData\Local\Temp\arduino_build_174251/WiFiProv.ino.partitions.bin \
0xe000 C:\Users\nicol\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.3/tools/partitions/boot_app0.bin \
0x10000 .pio\build\ESP32-S3\firmware.bin

Platform.io:

esptool.py --chip esp32s3 --port "COM4" --baud 460800 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size 8MB \
0x0000 C:\Users\nicol\.platformio\packages\framework-arduinoespressif32\tools\sdk\esp32s3\bin\bootloader_dio_80m.bin \
0x8000 C:\Users\nicol\OneDrive\Documents\PlatformIO\Projects\provisioning_repro\.pio\build\ESP32-S3\partitions.bin \
0xe000 C:\Users\nicol\.platformio\packages\framework-arduinoespressif32\tools\partitions\boot_app0.bin \
0x10000 .pio\build\ESP32-S3\firmware.bin

Based on this, I tested out several things using esptool.py manually:

• Using the "Arduino IDE version of the command, but replacing just my own code (the path to firmware.bin at the end, obviously) with the version built with Platform.io: this works!
• Replacing the other binaries uploaded one by one to isolate a cause: partitions.bin and boot_app0.bin have no effect, and indeed the binary files Pure Arduino and Platform.io point to are identical

That left me with the bootloader as a potential culprit. A binary diff of the “temp” bootloader the Arduino IDE uses (C:\Users\nicol\AppData\Local\Temp\arduino_build_174251/WiFiProv.ino.bootloader.bin in my case) with the files found in the Arduino IDE install (C:\Users\nicol\AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.3\tools\sdk\esp32s3\bin for me) shows something very interesting: the bootloader being uploaded is bootloader_qio_80m.bin. Note: Qio, not Dio. This is not a typo on my end, despite the esptool.py command being issued with --flash_mode dio!

Indeed, armed with this, I tried a manual upload again with just files from Platform.io like this:

esptool.py --chip esp32s3 --port "COM4" --baud 460800 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 80m --flash_size 8MB \
0x0000 C:\Users\nicol\.platformio\packages\framework-arduinoespressif32\tools\sdk\esp32s3\bin\bootloader_qio_80m.bin \
0x8000 C:\Users\nicol\OneDrive\Documents\PlatformIO\Projects\provisioning_repro\.pio\build\ESP32-S3\partitions.bin \
0xe000 C:\Users\nicol\.platformio\packages\framework-arduinoespressif32\tools\partitions\boot_app0.bin \
0x10000 .pio\build\ESP32-S3\firmware.bin

This is the exact same command as the one issued natively by Platform.io, including setting --flash-mode dio, EXCEPT that the bootloader used in the QIO file.

This fixes the issue for me, but obviously a) I don’t want to have to upload manually and b) this opens up a whole lot of questions like “am I doing something fundamental very wrong or is there some odd bug here?” 😃

(sidenote: I tested changing --flash_mode to qio to match the bootloader: this seems to result in a boot loop on my device).

Thanks in advance for any help!

[valeros]

Thanks for testing, fixed in the dev branch.

[Ezekiel-DA]

Thank you for the clarification! I’ll admit I’m a little out of my depth here, while the software part is in my wheelhouse, I’m not familar enough with the hardware side to understand all the details.

Given that this is an original Espressif board, should the default behavior for board = esp32-s3-devkitc-1 be changed to automatically use board_build.flash_mode= qio? As it stands, this board doesn’t work out of the box with the basic WifiProv example, and I assume this behavior extends to not saving other things to flash?