This is coming almost all the time in RUI 4.0.6
There has been mentioned that a 10 ms delay should be inserted before issuing an AT Command. This always happen when you get a message from the RAK3172.
before the AT command.
This is obviously a bug. inserting a 10 ms delay is a work around
This issue did not exist in older versions of the RUI.
I noticed that each RAK3172 module is different, some modules don’t need 10 ms 4 ms is enough.
Please fix this bug, it’s annoying.
If you get this, then most likely there is still something in the TX buffer of your host MCU that is sent out together with your command.
I have seen as well that glitches on the TX at the host MCU are causing this message on the next AT command.
Waiting before sending the next command is a bad practice. You should always read the whole response from the RAK3172 before you send the next command.
Commands are either finished after the RAK3172 has sent it’s “OK” or an error message like “AT_PARAM_ERROR”.
Your interpretation of this issue is not correct.
I’m telling you what I see on the oscilloscope.
I can see the message come from the RAK3172 +EVT:TXP2P DONE
Than a few milliseconds later the MCU sends AT+PRECV=65534
Then a few milliseconds later RAK3172 responds AT_COMMAND_NOT_FOUND.
And this is an ESP32 as host MCU sending AT commands to a RAK3172 over UART
Lines with >> are the commands sent to the RAK3172
Lines with <<` are the response from the RAK3172
This has been reported here in the Forum.
It seems like the problem is not consistent, some modules have it, some don’t.
But it is areal.
You need to see the timing on the scope. If there is sufficient delay already in the firmware,
then most likely the problem won’t show up.