Changing RAT to GSM causes indefinite reboot loop


Hi folks. I have a problem, I am starting legato with radio OFF, then I am executing cm radio rat GSM, everything seems to be OK, but when I am switching radio on, the module reboots immediately and only solution to make it boot is physically turning the radio off. Then module boots and I have chance to change RAT back to UMTS or AUTO, in these modes legato works perfect. There is no difference, where I am trying to change RAT manually, same scenario appears when I make it from code. Actually, there is one and only case when I can make it change, if I remove a SIM card cm radio rat GSM actually changes RAT and then I can see this change when executing cm radio, but if I insert a SIM, the module reboots again. Is there any chance to make GSM work?

Legato version: 16.07.0
Device: WP8548
Firmware: SWI9X15Y_07.11.09.00 r32989 CARMD-EV-FRMWR1 2016/08/11 18:03:20

Please help!


Ok, I’ve found the root of the problem.

According to mangOH™ Green (DV4) Developer’s Guide I can use 4.5V to 17V power supply, so I used 5V 2A supply and connected it to DC jack, and 5V seems to be not sufficient for stable work of WP8548, I have tried to connect 12V supply and there is no sudden reboots so far.