Module stuck in CFUN=0 with "Volt:1"

IoT Modules MC/EM Series
1

I have an old MC7710 that I cannot bring online with AT+CFUN=1.

ATI
Manufacturer: Sierra Wireless, Incorporated
Model: MC7710
Revision: SWI9200X_03.05.29.03ap r6485 CNSHZ-ED-XP0031 2014/12/02 17:53:15
IMEI: XXXXXXXXXXXXXXXXXXXXXX
IMEI SV: 23
FSN: XXXXXXXXXXXXXXXXXXXXXX
3GPP Release 8
+GCAP: +CGSM,+DS,+ES
OK

AT+CFUN?
+CFUN: 0
OK

AT+CFUN=1
ERROR

Debugging the issue, I found there is a Volt:1 LPM force flag reported, and High Critical Volt state:

AT!PCINFO?
State: 0 (LPM)
LPM force flags - W_DISABLE:0, User:0, Temp:0, Volt:1, Auth:0
W_DISABLE: 0
Poweroff mode: 1
LPM Persistent: 0
OK

AT!PCVOLT?
Volt state: High Critical
Power supply voltage: 3607 mV (139 cnt)
OK

The module is connected with a miniPCI to USB adapter to the PC.

I don’t understand the problem and the errors reported. Is the module receiving more voltage than expected from the USB port? Is this a hardware issue with the miniPCI adapter that is not limiting the power to 3.3V correctly before passing it to the module?

I know this module is old and unsupported, but the PCINFO? and PCVOLT? commands are still used in all new modules. We’re trying to add some automatic problem detection logic based on those, but we need to understand the issue first.

Thanks

2

What will happen if you give 3.3v voltage?

Here is the response of my MC7455:

at!pcvolt?
Volt state: Normal
Power supply voltage: 3257 mV (ADC: 35770)

OK
ati3
Manufacturer: Sierra Wireless, Incorporated
Model: MC7455
Revision: SWI9X30C_02.30.01.01 r7792 CARMD-EV-FRMWR2 2018/07/13 02:24:52
MEID: 35907206044378
IMEI: 359072060443781
IMEI SV: 16
FSN: LQ648230020110
+GCAP: +CGSM

OK

3

I will test with a different miniPCI adapter to see what happens.

4

Tested with a different adapter, and CFUN=1 can now work:

AT!PCVOLT?
Volt state: Normal
Power supply voltage: 3273 mV (126 cnt)
OK

AT+CFUN=1
OK

Thanks for looking at this issue.