Issue with GPS in EM7355

IoT Modules MC/EM Series
21

I ran the AT!GCCLR command and successfully cleared the crash dump. Accessed the GPS COM port with PuTTY and it ran until the card reset. Here is what the crash dump contained.

at!gcdump

Src: FatalError
Dat: 00001388
Str: OSTIMERSTART - timer already running
Fmt: OSTIMERSTART - timer already running
00000000 00000000 00000000 00000000
Prc: MPSS
Task: GPS
Time: 02C6FFC6
R0: 43740BA2 R1: 00001388 R2: 41897458 R3: 452D3F48 R4: 452D3F48
R5: 00000238 R6: 00000000 R7: 00000000 R8: 000000FE R9: 00000000
R10: 0486CDDE R11: 00000000 R12: 80000000 R13: 00000000 R14: 4540D7DB
R15: BABF2C26 R16: 43740BA2 R17: 00001388 R18: 00000008 R19: 44257308
R20: 44257308 R21: 00000594 R22: 4425705A R23: 00000000 R24: 44257F1D
R25: 4511A940 R26: 4511B2D0 R27: 4511AFA0 R28: 00000000 SP: 4540D478
FP: 4540D480 LR: 41F8B320
PC: 41F5025C
CPSR: 00008000
Mod: Unknown
Ctr: ARM, IRQ dis,FIQ dis
TOS
44257898 00001388 4540D490 41F8B378 44256930 442578E4 4540DCA8
41F55E60 0000ABAB 0000ABAB 000003E8 00000001 0000000A 000000FF
0000AB0C 0000ABAB 00000001 003E000A 00290150 00000001 0005000C
001F006F 00000001 0009000F 001E0040 00000001 00230012 002300AC
00000001 00400017 00250049 00000001
BOS

OK

22

But in ubuntu case, it is not related to gps?

23

No I’ve had the same the results in Ubuntu as well. There’s no pattern to the reset either. I’ve seen this occur anywhere from a few hours to a day both in Windows and Ubuntu. The COM port closes on the GPS and network drops out.

I will run another test in Ubuntu and get the dump from there for comparison.

24

BTW, have you tried the latest FW?

https://source.sierrawireless.com/resources/airprime/software/airprime-em73xx_mc73xx-fw-package-build-4837/#sthash.JQ672P4x.dpbs

25

All our 7355s are running the latest firmware. Also, my test laptop is running the latest driver as well. All other laptops have an older version of driver but so far the results are the same across all of them.

26

Seems this is not latest fw

AT!GVER?
!GVER: SWI9X15C_05.05.58.01 r27044 carmd-fwbuild1 2015/03/05 00:02:40

27

You are correct. I checked the list again and see that there is a version SWI9X15C_05.05.58.05 for Verizon, which these are Verizon cards. Should have read the numbers a little closer. I will test this newer version today.

28

I attempted to update the firmware on my test laptop to 05.05.58.05 Friday but ran into issues getting the card to take the firmware. After several attempts, the card either bricked itself or lost the bootloader. Based on my own research, its most likely the bootloader.

Fortunately I had a spare 7355 available. I installed it and got it working. This card still had firmware version 05.05.16.03. I decided to do some testing with this firmware version and found that the issue with the GPS wasn’t present. I successfully ran the GPS all weekend without a failure. Its looking more like this issue is a firmware problem. I’m going to continue experimenting.

29

Was finally about to get the firmware in my test card to update to the latest firmware version of 05.05.58.05. I kept having issues with the update timing out so I reinstalled Windows and was finally able to get the card to take the new firmware.

So far on the new firmware, the GPS has not failed. I’ve had it running for 2 and half days now with out any failures or power cycles. It definitely appears to be a firmware issue. I’m going to update the firmware on several other laptops and see if this resolves the problem on them as well.

30

I have completed testing the firmware on multiple laptops. This new version of firmware solved the power cycling issue on each card. I will update all our other laptops to this version. Appreciate the help on this issue.