Hello

I have been trying using different usb to serial TTL adapters to switch these modules into AT mode.

I can read from this forum that some people has been facing this issue too.

I have used different software terminal tools including the tools supplied by WCH.

Also used several modules with same behaivor.

The CH9141K-EVT-R3-1v0 module doesn't react to "AT..." or any other AT command.

Transperant mode works.

When module boots it writes "welcomme" in the terminal.

So serial communication seems to be ok (and transperant mode also works).

Pulling the AT pin low (force AT mode) makes the module reply "err: 02" to all AT commands.
Do I need a module FW update ?

And how do I do that ?

Thanks in advance.

For the 9141 chip, AT command configuration is supported.
Based on the official development board, the serial port and the chip are wired VCC GND TX RX, and others do not need to be connected.
After connecting, send AT commands through the serial port, send AT... (Enter line feed (rn)), so pay attention to whether the lack of line return feed causes problems with the AT command entry.