No screen (LYWSD03MMC 1.4 bricked ?) after downgrade tentative

[yan-064]

trafficstars

Hello,

I request your help after reading a lot of issues. For the context, I tried to downgrade a LYWSD03MMC v1.4 from 2.1.1_0159 to 1.0.0_0130 and now it seems to be bricked. No screen, no bluetooth connection.

For information, I use a FT232R usb-com adapter on a Windows computer. I read that Mac users seems to have the same trouble. I tried also on a second Windows computer, same result. However, I flashed with the online tool that returned success state many times with 2 or 3 wires as described here or here.

Anyone could please help me ? I don't know what to do.

Thanks.

[pvvx]

You need to flash the file: https://github.com/pvvx/ATC_MiThermometer/raw/master/ATC_v47.bin

README: The USB-COM adapter writes the firmware in explorer. Web version In difficult cases, when the chip contains an unknown FW, it is necessary to use a chip reset or power supply during "activation".

[yan-064]

Thanks for your feedback.

Yes, I saw that section "in difficult cases, when the chip contains an unknown FW, it is necessary to use a chip reset or power supply during "activation", but I don't understand what I really have to do.

I tried to put TX on vbat whithin the atime period and then put it back on p14. No effect, I don't know if it is the good handling.

I'll try with the atc_v47 instead of the xiaomi_ota_1.0.0.109.

Thanks

Le dim. 10 mars 2024, 00:00, Victor @.***> a écrit :

You need to flash the file: https://github.com/pvvx/ATC_MiThermometer/raw/master/ATC_v47.bin

README: The USB-COM adapter writes the firmware in explorer. Web version https://github.com/pvvx/ATC_MiThermometer?tab=readme-ov-file#the-usb-com-adapter-writes-the-firmware-in-explorer-web-version In difficult cases, when the chip contains an unknown FW, it is necessary to use a chip reset or power supply during "activation".

— Reply to this email directly, view it on GitHub https://github.com/pvvx/ATC_MiThermometer/issues/489#issuecomment-1987003071, or unsubscribe https://github.com/notifications/unsubscribe-auth/ANWUPTRNZAXLI3TYHCQJ5N3YXOIAVAVCNFSM6AAAAABEOKYQQWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSOBXGAYDGMBXGE . You are receiving this because you authored the thread.Message ID: @.***>

[yan-064]

Hi, I just tried with the atc_v47, always the same result. No screen, no bluetooth. It seems to be dead.

Who could explain me how to do that please ? => "In difficult cases, when the chip contains an unknown FW, it is necessary to use a chip reset or power supply during "activation"

I ever read that "At the same time, take into account that the chip can be powered from the TX output. This is solved by connecting TX and +Vbat during "activation". But I don't understand what I exactly have to do.

Does that mean that I have to :

• plug gnd to gnd
• plug Tx to vbat+
• click write to flash
• before 3s ellapsed, unplugged the Tx from vbat+ and plug it to p14
• wait for flash

I'm right ?

Thanks.

[pvvx]

1. Remove battery
2. GND -> GND
3. Set "Atime" to maximum value
4. "Erase All Flash"
5. Quickly connect: TX -> P14, 3V3 -> +Vbat

After these steps, when connecting the power, you will not need to reset or connect pins on the fly and programming should be successful.

[yan-064]

Thanks again for your help. Unfortunately, same result. I follow your steps like that :

• remove battery
• plug gnd on gnd
• set atime to 16s
• click erase all flash => countdown started
• quickly connect (before 16s) tx on p14 and 3.3v on vbat+
• wait for erase => success

Then I try to flash with atc_v47.bin.

• still no battery
• plug gnd on gnd
• plug tx on p14
• set atime to 3s and let default bauds (46080)
• select atc_v47 firmware
• click "Write to flash" ==> success

Logs here : 21:02:36: USB-COM opened. 21:02:38: File was selected, size: 83028 bytes 21:03:13: Reset DTR/RTS (100 ms) 21:03:13: Activate (3 sec)... 21:03:16: Write 83028 bytes in to Flash... 21:03:47: Done (34.521 sec). 21:03:47: Soft Reset MCU

Still not working, that makes me mad. Why did I update that Xiaomi firmware before checking on the web, so stupid.

[yan-064]

Hello,

Could you tell me if I'm doing something wrong ? I have a second thermometer on 2.1.1.0159 but I don't want to brick it 😅.

Thanks, have a good day.

[zawatowskib]

@yan-064 did you get any chance solving this? I too could not get it to work. I assume the instructions were translated using google translate, so they are a bit vague. I have a FTDI based USB COM, might this be the issue?

[pvvx]

Option 2:

https://github.com/pvvx/TlsrComSwireWriter

File "https://github.com/pvvx/TlsrComSwireWriter/blob/master/TLSR825xComFlasher.py"

There is an example here: Flashing firmware with USB to UART

[dbarwikowski]

I was able to install ATC fw. Then wanted to flash BTH_v47 and after that looks like my thermomether is bricked. I've spent already few hours googling and trying different things.

I have CH340 programmator. I don't know if that's a problem.

I can provide more information with photos and diagrams if needed.

[yan-064]

@yan-064 did you get any chance solving this? I too could not get it to work. I assume the instructions were translated using google translate, so they are a bit vague. I have a FTDI based USB COM, might this be the issue?

Hello, no I gave up. I don't know why it's not working for me. I'll look at the option 2.

[zawatowskib]

Option 2:

https://github.com/pvvx/TlsrComSwireWriter

File "https://github.com/pvvx/TlsrComSwireWriter/blob/master/TLSR825xComFlasher.py"

There is an example here: Flashing firmware with USB to UART

Thanks, will try this later. I'll need another UART converter, as FTDI chip is indeed not supported apparently.