WISMO218: AT initial sequence?

I have problem with wismo 218. It have worked for a short period of time, and only for a few seconds it responded to at+creg=? with 0,1… All other time it’s 0,3%; 0,4%…

Also, after XX number of seconds it would stop responding on AT commands…

What is the usual init sequence for wismo? I use 3 wire UART connection (just GND, TX and RX) on 115200bps…

Thank you…

Maybe it enters in the sleep mode. There is a reference scheme for connecting wismo without DTR control. Try to reproduce it.

Check your filter cap. If your power supply is not sufficient, the WISMO218 will shut down when it attempts to transmit (a few seconds after power on).
Mick.