MC7455 going into LPM mode randomly

IoT Modules MC/EM Series
1

We are using MC7455 with AT&T SIM, during testing we found the MC7455 SIM goes into LPM mode randomly.

If we reboot the device LPM mode recovers sometimes, but not always. Any idea why device is going into LPM mode?

AT!GSTATUS?
AT!GSTATUS?
!GSTATUS:
Current Time: 13156 Temperature: 31
Reset Counter: 6 Mode: LOW POWER MODE

OK

done.
Enter AT commands ex ATI. Press q to exit.

At!PCINFO?
At!PCINFO?
State: Low Power Mode
LPM voters - Temp:0, Volt:0, User:1, W_DISABLE:0, IMSWITCH:0, BIOS:0, LWM2M:0, O
MADM:0, FOTA:0
LPM persistence - User:1

OK

done.
Enter AT commands ex ATI. Press q to exit.

At!IMAGE?
At!IMAGE?
TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID
FW 1 GOOD 4 0 0 ?? 02.08.02.00?
FW 2 GOOD 1 0 0 ?? 02.05.07.00?
FW 3 GOOD 1 0 0 ?? 02.14.03.02?
FW 4 GOOD 5 0 0 ?? 02.24.05.06?
Max FW images: 4
Active FW image is at slot 4

TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID
PRI FF GOOD 0 0 0 002.027_000 02.24.05.06_ATT
PRI FF GOOD 0 0 0 002.007_001 02.08.02.00_GENERIC
PRI FF GOOD 0 0 0 002.012_001 02.14.03.02_SPRINT
PRI FF GOOD 0 0 0 001.000_000 00.00.00.00_OEMPRI918
PRI FF GOOD 0 0 0 002.008_003 02.05.07.00_VERIZON
Max PRI images: 50

OK

done.
Enter AT commands ex ATI. Press q to exit.

Any pointers to debug it further would be appreciated?

2

@vikashj,

Typically the User cause is the at+cfun=0 command being sent to it. A reset will recover the unit as this state is not persistent across power cycles.

Regards

Matt

3

But we are not sending any CFUN command from code or user, so why device going into LPM mode. We do use PkQmiDmsSetOperatingMode (Power-on, off, airplane) during data session initiation. Will that cause modem to go into LPM mode.

Basically when we disable cell interface, we power-off the the device and when we enable we power on the device back.

4

@vikashj,

That could possibly do it, airplane mode is effectively low power mode.

Regards

Matt

1 Like
5

Thanks, we corrected the code and it seems no LPM mode. Thanks a ton for your help