I’m starting to debug a circuit board that incorporates a HL6528 module. The circuit uses a single SIM socket, connected to UIM1. All GPIO pins are left open.
When I issue AT+CPIN?, I get “+CME ERROR: SIM not inserted”. (I’ve tested with a number of different SIMs.)
The non-SIM related commands I’ve experimented with seem to give sensible responses, but I note that AT+KTEMPMON=1 gives “+CME ERROR: memory failure”.
Can anyone suggest what I should be looking for at this stage?