ESPHome OTA does not apply (Tuya T34 BK7231N)

[mvoss96]

Im trying to convert a Nous A8M smart plug to esphome.
It uses a tuya T34 chip (BK7231N).

First i flashed openBeken using serial and tried to convert to esphome using the kickstart image.
However the ota showed as successful but after reboot the device still booted openbeken.

Than i flashed a minimal esphome image using ltchiptool over uart. That worked and the device appears in esphome dashboard.
However i can still not update via ota. The log shows the ota as successful but after a reboot there are no changes and still the old firmware runs.

I guess the problem is that the partition swap does not work?

Can someone help me with that?

[kuba2k2]

The problem is most likely due to wrong OTA offset being used.
You need to post the firmware dump of the device (can be post-conversion as well).
The bootloader has the OTA offset written in it.

[mvoss96]

thanks, i will gladly provide the firmware dumps both before (readResult_...) and after (ltchiptool_...) conversion;:
https://limewire.com/d/Yl7Tp#5w5iaqml5U

[kuba2k2]

Your device seems to be using a bootloader version 3.0.0, which is apparently not supported yet. It's likely due to the plug being a Matter device.

The easiest way around it will probably be to flash a "standard" 1.0.1 bootloader, like this one:
bk7231n-1.0.1-encrypted-tuya.zip

Flash using ltchiptool. Offset 0x0, length 0x11000. It's safe on BK7231N, you won't brick the device, you can always go back to the previous one.

[mvoss96]

thanks that worked.
After flashing the 1.0.1 bootloader the esphome ota works

[dlushni]

Similar issue with Moes WS-B-US smart switches. There are two versions of the switch. Both use Tuya CBU modules that are physically identical and the minor PCB layout changes on the actual switch didn't seem relevant. Older version can be flashed using ltchiptool and ESPHome OTA without any issues at all. Newer version of the switch does have Matter support and I've experienced very similar symptoms where OTA updates report success, but none of them were ever actually applied. Some of the flash attempts using ltchiptool also didn't stick, without any apparent errors in the logs, but I was eventually able to flash my full ESPHome UF2 image successfully over UART. Not too sure if there was any particular pattern to these failed attempts to flash over UART.

I'll try the older bootloader and report back.

[dlushni]

Downgrading from bootloader v3.00 to 1.00 did solve the problem with OTA. It does switch over to the new ESPHome FW successfully after the update, but it seems like I've only just started to peel the onion.

It looks like the entire flash map is now different on the new CBU modules with the v3.00 bootloader. With app partition a lot bigger than before and other regions moved around to accommodate for that. The new layout also seems to be different than the 7231q/7231t layout. Curiously the bootloader got smaller, the v3.00 is about 3/4 the size of what v1.00 was.

The way I found out about that is when I noticed all devices now have the same MAC address: C8:47:8C:42:00:48 and WiFi performance is noticeably worse than before, even without all the MAC address conflicts.

Trying to decide now if I want to convert the entire image in flash to the old format now (by moving stuff around manually) or remap ESPHome image to match the new layout using

platformio_options:
    board_flash.xx

Didn't expect this to be going on when dealing with exact same Tuya CBU modules using exact same BK7231N chips.

[dlushni]

I went with the hybrid approach using the manually flashed 1.00 bootloader and a flash layout (more or less) compatible with 3.00 layout. This seems to work well.

esphome:
  platformio_options: 
    board_build.bkboot_version: "1.0.1-bk7231n"
    board_flash.calibration: "0x1E3000+0x1000"
    board_flash.net: "0x1E4000+0x1000"
    board_flash.tlv: "0x1E6000+0x1000"
    board_flash.kvs: "0x1E7000+0x8000"
    board_flash.userdata: "0x1EF000+0x6000"
    board_flash.tuya: "0x1F5000+0xA000"

[divadiow]

thanks, i will gladly provide the firmware dumps both before (readResult_...) and after (ltchiptool_...) conversion;: https://limewire.com/d/Yl7Tp#5w5iaqml5U

this dump =

partition    flash_name       addr       size
------------ ---------------- ---------- ----------
bootloader   beken_onchip_crc 0x00000000 64K
app          beken_onchip_crc 0x00010000 1083136
download     beken_onchip     0x0012A000 664K