MC7455 stops working

IoT Modules MC/EM Series
1

We have problems with several MC7455 modules on a Windows 7 embedded system. Some of the modules stop working after days or weeks of operation. First they disappear from the device manager. And later some even prevent the systems from rebooting as BIOS issues beep code 3 long 2 short.

On one of the still operational systems the at!gcdump output showed the following error:

Src: FatalError
File: lte_ml1_schdlr2_stm.c
Line: 1265
Str: Assertion 0 failed
00000000 00000000 00000000 00000000
Prc: MPSS
Task: ML1
Time: 0C813D32
R0: EC902000 R1: DE5C2D38 R2: 58D0A334 R3: 00F5A2F1 R4: 000058D0
R5: 00000000 R6: 000000A2 R7: 00000000 R8: 00F5A2F1 R9: 00000000
R10: 000000F5 R11: 7EC171CD R12: 000000F5 R13: 00000000 R14: 00000000
R15: 00000000 R16: 055607E0 R17: 00000000 R18: 00000000 R19: 0384DF30
R20: 000000C4 R21: 000000FD R22: 018E97CC R23: 00000000 R24: 00000001
R25: 018E8E08 R26: 00000001 R27: 00000000 R28: 00000000 SP: 1E9DEA78
FP: 1E9DEA80 LR: 02129158
PC: 01BD1E6C
CPSR: 00000000
Mod: Unknown
TOS
1E9DEA98 02129198 00003D5F 0384DF30 0384DF28 00000000 1E9DEBF8
01BD1E6C 000000C4 00001560 0000155F 00003D5F 9135F8AC 000005DC
9135F84E 000005DC FFFFFFFF 00000000 00000030 00000739 00000030
00000739 00001560 00001560 00000000 00000000 9135F8AC 000005DC
9135F84E 000005DC FFFFFFFF 00000000
BOS
App ver: SWI9X30C_02.24.05.06

OK

Are we facing hardware failures? Or can it be resolved with e.g. SW update? We are using “GenericDriverSetup_5087” and have set the interface to at!usbcomp=1,1,50d. The voltage quere at!pcvolt? gives 3316mV.

Please can you give advice of how to resolve the failures?

2

have you tried the latest FW?

3

I just tried the latest FW 02.33.03.00.

Now I can’t connect to the carrier anymore. Even if I go back to the older FW.

Somehow the device seems broken. HW failure?

4

What is at!gstatus? returned

5

at!gstatus?
!GSTATUS:
Current Time: 21 Temperature: 39
Reset Counter: 3 Mode: ONLINE
System mode: WCDMA PS state: Not attached
WCDMA band: WCDMA 2100
WCDMA channel: 10674
GMM (PS) state:DEREGISTERED PLMN SEARCH
MM (CS) state: IDLE PLMN SEARCH

WCDMA L1 state:L1M_ACQ LAC: 0000 (0)
RRC state: DISCONNECTED Cell ID: 00000000 (0)
RxM RSSI C0: — RxD RSSI C0: —
RxM RSSI C1: — RxD RSSI C1: —

OK

But all is fine if I replace the module. Thus, system, drivers, antenna, SIM must be ok.

6

how about using AT!RMARESET

7

at!rmareset
ERROR

AT!RMARESET=1
!RMARESET: DEVICE REBOOT REQUIRED

Items Restored: 0
Items Deleted: 0

ERROR

at!image?
TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID
FW 1 GOOD 6 0 0 ?? 02.24.05.06?
FW 2 GOOD 4 0 0 ?? 02.33.03.00?
FW 3 GOOD 5 0 0 ?? 02.20.03.00?
FW 4 EMPTY 0 0 0
Max FW images: 4
Active FW image is at slot 1

TYPE SLOT STATUS LRU FAILURES UNIQUE_ID BUILD_ID
PRI FF GOOD 0 0 0 002.026_000 02.24.05.06_GENERIC
Max PRI images: 50

8

how about

AT!entercnd=“A710”
AT!impref?
AT!PCINFO?
At!band?
At!selrat?
At+cgdcont?

9

at!entercnd=“A710”
OK
AT!impref?
!IMPREF:
preferred fw version: 02.33.03.00
preferred carrier name: GENERIC
preferred config name: GENERIC_002.072_000
preferred subpri index: 000
current fw version: 02.33.03.00
current carrier name: GENERIC
current config name: GENERIC_002.072_000
current subpri index: 000

OK
AT!PCINFO?
State: Online
LPM voters - Temp:0, Volt:0, User:0, W_DISABLE:0, IMSWITCH:0, BIOS:0,
LWM2M:0, OMADM:0, FOTA:0
LPM persistence - None

OK
At!band?
Index, Name, GW Band Mask L Band Mask
TDS Band Mask
00, All bands, 0002000007C00000 00000100330818DF
0000000000000000

OK
At!selrat?
!SELRAT: 00, Automatic

OK
At+cgdcont?
+CGDCONT:
1,“IPV4V6”,“internet.t-mobile”,“0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0”,0,0,0,0

OK

10

Is the SIM card OK?
you can also check if AT+COPS=? can scan some network operator

Also what is the return of these?
AT!UIMS?
AT+CPIN?

11

SIM should be ok. Everything works if I repace the module.

at+cops?
+COPS: 0

OK
AT!UIMS?
!UIMS: 0

OK
AT+CPIN?
+CPIN: READY

OK

12

are you using GENERIC FW before?

13

Yes, the modul came with SWI9X30C_02.24.05.06_00_GENERIC_002.026
firmware and I updated to SWI9X30C_02.33.03.00_00_GENERIC_002.072 as
recommend by you.

In fact, the update worked on another device without problem. But this
other device had an empty crash dump log.

14

No idea if it only happens to particular module

15

Great, now I have a damaged device? How to return it? What about Sierra
customer support?

16

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