Zmai-90 CBU Module Flash Reading Issue: Beken Writer 1.60 Error & Python Script Troubleshooting

Hello,



I tried to read out the flash of the module before I flash a new software.



I soldered Rx1/Tx1 /CEN + 3,3V and connected it to two different USB / serial adapter.
Rx1 is connected to Tx and Tx1 is connected to Rx.

Used "Beken Writer 1.60" with the following config:

Press on "Read flash" connect CEN to GND for a short period and wait.
I can see that the display changes and the two LED on the board are changing (so rest works) but got only an error.

Next step I have tried to read out the flash by python script with the following result :

- I have changed Rx and Tx with out any result
- check several baud rates without andy result.

Woud be great if someone has an idea. Thank you Peter

Hello. Your device is most likely using some kind of UART protocol (if it's an older version of Zmai-90) or TuyaMCU protocol (if it'a a newer version). UART protocols are using the same pins that are used for programming - RXD1 and TXD1. TuyaMCU packets sent to WiFi module from the MCU may interfere with programming.

In order for it to work, you basically need to disconnect Wifi's RXD1 and TXD1 from TuyaMCU. This is done in various ways, depending on the device, sometimes you have to desolder a chip, sometimes to cut the trace...
In case of this switch, we had to desolder the buttons controller: https://youtu.be/JCqq-gn-X2c?t=190
In case of this relay, we had to remove capacitor and cut the trace: https://youtu.be/0V0kaRVnk18?t=257
but in case of this device...

Can you take off the PCB with WiFi module, power it from your 3.3V power supply (something with a reliable LDO, AMS1117, because current capability is important) and try again?

Hello,
I have the same module as you, the communication is switched to RX2 and TX2 pins, baud rate is 115200 and config is 8,N,1.
Have fun on this serial.

Your Zmai-90 is using RXD2/TXD2 for TuyaMCU?

TXD2 is a log output of Beken, not a TuyaMCU data port...

You might be right, all I saw was logs and debug data.
I have just fried mine by shorting the GND and N line by mistake while it was plugged in mains.
The game stops here for me, at least for now.
Please do tell if you manage to flash via serial.

Ah okay, so false alarm. You saw just the debug log output of Tuya firmware. The baud rate also fits.

Is your WiFi module also dead now? Maybe it survived, can you try desoldering it and reading it's flash?

Same at my zmai, i can't read something on him i dont know if will work via wi fi.

Thanks

I replaced the system with ESP in my Zmai.

Can you post what esp use? Because i dont find any esp with same pinout like cbu

Thanks

If the UART lines are in use and you don't want to cut the traces to remove the interference, you can always use this method:

Bk modules can be easily programmed outside circuit.

just adjust pinout to your need

I have this esp c05 but i think is not same pinout like cbu:



Yea is different because my chip have only 6 pins on left and right and cbu have 7 with 7.

Actually different pin spacing. I thought every Zmai had the same one.
Here's mine after disassembly

And the chip to replace CBU is out:

https://vi.aliexpress.com/item/10050049374977...436156311-00915-_dYc72Dj&gatewayAdapt=glo2vnm
https://templates.blakadder.com/ESP8685-WROOM-06.html

I bought 1 and am waiting for it to arrive for testing because this ZMAI is a problem with Read Data

I have worked on new Zmai-90 recently, the one that is using RN8209C for power metering. It's almost supported by OBK, but still WIP. See more here:
https://www.elektroda.com/rtvforum/topic4014818.html