MC8790 restarting when not connected


#1

Hello!

I have an MC8790 installed in an ARM system running Linux 3.0.4 using the sierra driver as a module.

The modem works as expected - I can query it for information using AT codes and set up a working PPP connection with my provider.

The problem:
When there is no reception (such as when the external antenna is removed or when a SIM is inserted which is out of range of its home station) the modem periodically (3-4 times per minute) disconnects itself from the USB and then reconnects after a few seconds.

This in itself is not a fatal problem, but after some random number of disconnect/connect cycles the modem no longer fully reconnects. Where there are usually seven serial lines /dev/ttyUSB[0-6] there is now only one, /dev/ttyUSB0, and a “ùsb storage device” /dev/sda.

The modem stays in this state (though still reconnecting periodically) until it is fully power cycled (i.e. the system fully powered off or the modem physically removed from the system and then reinserted). Simply rebooting the host system does not help if power is not fully removed.

Here is some information I’ve dumped from the modem using a chatscript when a SIM out of range is inserted:

AT

OK

AT+CFUN=1

OK

AT&V
&C: 1; &D: 2; &E: 1; &F: 0; &S: 0; &W: 0; E: 1; L: 0; M: 0; Q: 0; V: 1;
X: 1; Z: 0; \Q: 3; \S: 0; \V: 0; S0: 0; S2: 43; S3: 13; S4: 10; S5: 8;
S6: 2; S7: 50; S8: 2; S9: 6; S10: 14; S11: 95; S30: 0; S103: 1; S104: 1;
+FCLASS: 0; +ICF: 3,3; +IFC: 2,2; +IPR: 115200; +DR: 0; +DS: 0,0,2048,6;
+WS46: 12; +CBST: 0,0,1;
+CRLP: (61,61,48,6,0),(61,61,48,6,1),(240,240,52,6,2);
+CV120: 1,1,1,0,0,0; +CHSN: 0,0,0,0; +CSSN: 0,0; +CREG: 0; +CGREG: 0;
+CFUN:; +CSCS: "IRA"; +CSTA: 129; +CR: 0; +CRC: 0; +CMEE: 2; +CGDCONT: (1,"IP","internet.telenor.se","0.0.0.0",0,0)
; +CGDSCONT: ; +CGTFT: ; +CGEQREQ: ; +CGEQMIN: ; +CGQREQ: ; +CGQMIN: ;
+CGEREP: 0,0; +CGDATA: "PPP"; +CGCLASS: "A"; +CGSMS: 0; +CSMS: 0;
+CMGF: 0; +CSAS: 0; +CRES: 0; +CSCA: "",; +CSMP: ,,0,0; +CSDH: 0;
+CSCB: 0,"",""; +FDD: 0; +FAR: 0; +FCL: 0; +FIT: 0,0; +ES: ,,;
+ESA: 0,,,,0,0,255,; +CMOD: 0; +CVHU: 0; +CPIN: ^?^?^?^?^?^?^?^?,^?^?^?^?^?^?^?^?;
+CMEC: 0,0,0; +CKPD: 1,1; +CIND: 0,0,0,0,0,0,0,0; +CMER: 0,0,0,0,0;
+CGATT: 0; +CGACT: 0; +CPBS: "SM"; +CPMS: "SM","SM","SM";
+CNMI: 0,0,0,0,0;  +CMMS: 0; +FTS: 0; +FRS: 0; +FTH: 3; +FRH: 3; +FTM: 96;
+FRM: 96; +CCUG: 0,0,0; +COPS: 0,0,""; +CUSD: 0; +CAOC: 1; +CCWA: 0;
+CCLK: ""; +CPOL: 0,2,"",0,0,0; +CPLS: 0; +CTZR: 0; +CTZU: 0; +CLIP: 0;
+COLP: 0; +CDIP: 0; +CLIR: 0; +CMUX: 0,0,5,31,10,3,30,10,2;
!CMUX: 0,0,5,31,10,3,30,10,2

OK

AT+CPOL?
+CPOL: 1,2,"23801"
+CPOL: 2,2,"24491"
+CPOL: 3,2,"24202"

OK

AT+COPS=3,0

OK

AT+COPS?
+COPS: 0

OK

AT+COPS=3,2

OK

AT+COPS?
+COPS: 0

OK

AT+CGREG?
+CGREG: 0,0

OK

AT^SYSCONFIG?
^SYSCONFIG: 2,2,1,2

OK

AT^SYSINFO
^SYSINFO: 0,0,0,0,1

OK

AT!GSTATUS?
!GSTATUS: 
Current Time:  208^I^ITemperature: 44
Bootup Time:   202^I^IMode:        ONLINE         
System mode:   GSM        ^IPS state:    Not attached 
WCDMA band:    IMT2000    ^IGSM band:    Unknown    
WCDMA channel: 10787^I^IGSM channel: 65535
GMM (PS) state:DEREGISTERED   ^IPLMN SEARCH    
MM (CS) state: IDLE           ^IPLMN SEARCH    
WCDMA L1 State:L1M_BCH        ^IRRC State:   DISCONNECTED   
RX level (dBm):-90

OK

AT!GSMINFO?
!GSMINFO: 
Serving Cell:
Not Available

OK

AT!PCVOLT?
Volt state: Normal
Power supply voltage: 3304 mV (163 cnt)

OK

AT!GVER?
!GVER: K2_0_7_35AP C:/WS/FW/K2_0_7_35AP/MSM6290/SRC 2010/03/04 17:37:08

OK

Here is my dmesg showing the moment when the proper state is lost and the modem goes into the problem state:

usb 1-3: new high speed USB device number 7 using ehci_hcd
usb 1-3: New USB device found, idVendor=1199, idProduct=683c
usb 1-3: New USB device strings: Mfr=3, Product=2, SerialNumber=0
usb 1-3: Product: MC8790
usb 1-3: Manufacturer: Sierra Wireless, Incorporated
sierra 1-3:1.0: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB0
sierra 1-3:1.1: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB1
sierra 1-3:1.2: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB2
sierra 1-3:1.3: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB3
sierra 1-3:1.4: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB4
sierra 1-3:1.5: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB5
sierra 1-3:1.6: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB6
usb 1-3: USB disconnect, device number 7
sierra ttyUSB0: Sierra USB modem converter now disconnected from ttyUSB0
sierra 1-3:1.0: device disconnected
sierra ttyUSB1: Sierra USB modem converter now disconnected from ttyUSB1
sierra 1-3:1.1: device disconnected
sierra ttyUSB2: Sierra USB modem converter now disconnected from ttyUSB2
sierra 1-3:1.2: device disconnected
sierra ttyUSB3: Sierra USB modem converter now disconnected from ttyUSB3
sierra 1-3:1.3: device disconnected
sierra ttyUSB4: Sierra USB modem converter now disconnected from ttyUSB4
sierra 1-3:1.4: device disconnected
sierra ttyUSB5: Sierra USB modem converter now disconnected from ttyUSB5
sierra 1-3:1.5: device disconnected
sierra ttyUSB6: Sierra USB modem converter now disconnected from ttyUSB6
sierra 1-3:1.6: device disconnected
usb 1-3: new high speed USB device number 8 using ehci_hcd
usb 1-3: New USB device found, idVendor=1199, idProduct=683c
usb 1-3: New USB device strings: Mfr=3, Product=2, SerialNumber=0
usb 1-3: Product: MC8790
usb 1-3: Manufacturer: Sierra Wireless, Incorporated
sierra 1-3:1.0: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB0

Summary

  • What causes the modem to reconnect when there is no base station?
  • What is this mode where the modem only provides a single serial interface? Is there a way to get out of it through software means?

Thank you kindly for your responses!


#2

Hi,

The best way to proceed is to use latest FW and see if same USB connect/disconnect happens when there is no network coverage.

This is not normal and current FW running is almost 3 years old already…

Hope it helps.
L


#3

Thank you for your reply!

Could you point me to documentation on upgrading the firmware from a linux system?

I’ve since performed more tests and come across the same problem with an MC8705 as well. On a few occasions I’ve been able to connect to the network and set up a working PPP connection with this MC8705, something which never works with the 8795.

I was mistaken about the USB storage device /dev/sda, it is not from the modem.

Here’s dmesg from the MC8705
The restarts happen roughly once every 25 seconds and after about 10 minutes the single-interface state is entered.

usb 1-3: USB disconnect, device number 34
sierra ttyUSB0: Sierra USB modem converter now disconnected from ttyUSB0
sierra 1-3:1.0: device disconnected
sierra ttyUSB1: Sierra USB modem converter now disconnected from ttyUSB1
sierra 1-3:1.1: device disconnected
sierra ttyUSB2: Sierra USB modem converter now disconnected from ttyUSB2
sierra 1-3:1.2: device disconnected
sierra ttyUSB3: Sierra USB modem converter now disconnected from ttyUSB3
sierra 1-3:1.3: device disconnected
sierra ttyUSB4: Sierra USB modem converter now disconnected from ttyUSB4
sierra 1-3:1.4: device disconnected
usb 1-3: new high speed USB device number 35 using ehci_hcd
usb 1-3: config 1 has an invalid interface number: 7 but max is 5
usb 1-3: config 1 has no interface number 5
usb 1-3: New USB device found, idVendor=1199, idProduct=68a3
usb 1-3: New USB device strings: Mfr=3, Product=2, SerialNumber=4
usb 1-3: Product: MC8705
usb 1-3: Manufacturer: Sierra Wireless, Incorporated
usb 1-3: SerialNumber: 353567040885692
sierra 1-3:1.0: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB0
sierra 1-3:1.1: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB1
sierra 1-3:1.2: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB2
sierra 1-3:1.3: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB3
sierra 1-3:1.4: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB4
usb 1-3: USB disconnect, device number 35
sierra ttyUSB0: Sierra USB modem converter now disconnected from ttyUSB0
sierra 1-3:1.0: device disconnected
sierra ttyUSB1: Sierra USB modem converter now disconnected from ttyUSB1
sierra 1-3:1.1: device disconnected
sierra ttyUSB2: Sierra USB modem converter now disconnected from ttyUSB2
sierra 1-3:1.2: device disconnected
sierra ttyUSB3: Sierra USB modem converter now disconnected from ttyUSB3
sierra 1-3:1.3: device disconnected
sierra ttyUSB4: Sierra USB modem converter now disconnected from ttyUSB4
sierra 1-3:1.4: device disconnected
usb 1-3: new high speed USB device number 36 using ehci_hcd
usb 1-3: New USB device found, idVendor=1199, idProduct=68a3
usb 1-3: New USB device strings: Mfr=3, Product=2, SerialNumber=4
usb 1-3: Product: MC8705
usb 1-3: Manufacturer: Sierra Wireless, Incorporated
usb 1-3: SerialNumber: 353567040885692
sierra 1-3:1.0: Sierra USB modem converter detected
usb 1-3: Sierra USB modem converter now attached to ttyUSB0

Here’s the info dump from the MC8705

AT
OK
AT+CFUN=1
OK
AT&V
&C: 1; &D: 2; &E: 0; &F: 0; &S: 0; &W: 0; E: 1; L: 0; M: 0; Q: 0; V: 1;
X: 1; Z: 0; \Q: 3; \S: 0; \V: 0; O: 0; S0: 0; S2: 43; S3: 13; S4: 10;
S5: 8; S6: 2; S7: 50; S8: 2; S9: 6; S10: 14; S11: 95; S30: 0; S103: 1;
S104: 1; +FCLASS: 0; +ICF: 3,3; +IFC: 2,2; +IPR: 115200; +DR: 0;
+DS: 0,0,2048,6; +CMEE: 2; +WS46: 12; +CBST: 0,0,1;
+CRLP: (61,61,48,6,0),(61,61,48,6,1),(240,240,52,6,2);
+CV120: 1,1,1,0,0,0; +CHSN: 0,0,0,0; +CSSN: 0,0; +CREG: 0; +CGREG: 0;
+CFUN:; +CSCS: "IRA"; +CSTA: 129; +CR: 0; +CRC: 0; +CGDCONT: (1,"IP","maingate.telia.se","",0,0)
; +CGDSCONT: ; +CGTFT: ; +CGEQREQ: ; +CGEQMIN: ; +CGQREQ: ; +CGQMIN: ;
+CGEREP: 0,0; +CGDATA: "PPP"; +CGCLASS: "A"; +CGSMS: 0; +CSMS: 0;
+CMGF: 0; +CSAS: 0; +CRES: 0; +CSCA: "",; +CSMP: ,,0,0; +CSDH: 0;
+CSCB: 0,"",""; +FDD: 0; +FAR: 0; +FCL: 0; +FIT: 0,0; +ES: ,,;
+ESA: 0,,,,0,0,255,; +CMOD: 0; +CVHU: 0; +CPIN: ^?^?^?^?^?^?^?^?,^?^?^?^?^?^?^?^?;
+CMEC: 0,0,0; +CIND: 0,0,0,0,0,0,0,0; +CMER: 0,0,0,0,0; +CGATT: 0;
+CGACT: 0; +CPBS: "SM"; +CPMS: "SM","SM","SM"; +CNMI: 0,0,0,0,0;
+CMMS: 0;  +FTS: 0; +FRS: 0; +FTH: 3; +FRH: 3; +FTM: 96; +FRM: 96;
+CCUG: 0,0,0; +COPS: 0,0,""; +CUSD: 0; +CAOC: 1; +CCWA: 0; +CCLK: "";
+CPOL: 0,2,"",0,0,0; +CPLS: 0; +CTZR: 0; +CTZU: 0; +CLIP: 0; +COLP: 0;
+CDIP: 0; +CLIR: 0; +VTS: 0; +CMUX: 0,0,5,31,10,3,30,10,2

OK
AT+COPS=3,0
OK
AT+COPS?
+COPS: 0

OK
AT+COPS=3,2
OK
AT+COPS?
+COPS: 0

OK
AT+COPS=?
+COPS: (1,"TELIA S","TELIA","24001",0),(1,"240 - 24","240 - 24","24024",0),(3,"SWEDEN","SWE","24004",2),(3,"Sweden 3G","Sweden3G","24005",2),,(0,1,2,3,4),(0,1,2)

OK
AT+CGREG?
+CGREG: 0,0

OK
AT^SYSCONFIG?
OK
AT^SYSINFO
OK
AT!GSTATUS?
!GSTATUS:
Current Time:  3689^I^ITemperature: 59
Bootup Time:   3647^I^IMode:        ONLINE
System mode:   GSM        ^IPS state:    Not attached
WCDMA band:    IMT2000    ^IGSM band:    Unknown
WCDMA channel: 10812^I^IGSM channel: 65535
GMM (PS) state:DEREGISTERED   ^IPLMN SEARCH
MM (CS) state: IDLE           ^IPLMN SEARCH

WCDMA L1 State:L1M_ACQ        ^IRRC State:   DISCONNECTED
RX level (dBm):-69


OK
AT!GSMINFO?
!GSMINFO:
Serving Cell:
Not Available


OK
AT!PCVOLT?
Volt state: Normal
Power supply voltage: 3204 mV (133 cnt)


OK
AT!GVER?
!GVER: T1_0_1_1AP R309 CNSZXL00000015 2011/01/21 18:28:30

OK
AT!ERR
QDSP6                             ARM9 (not saved)
00   0C uim              08480    00   01 hsu_conf_sel_nv  00572
01   53 gsnvif           00245    01   01 hsu_conf_sel_nv  00616
02   FF cmtask           01162    02   01 timer            03552
03   1E mmglbl           00391
04   1E gsnvif           00478
05   1E rr_init          01597
06   1E rr_init          01601
07   1E rrcdata          07849
08   01 gmmutil          01097
09   01 gmmutil          01116
10   01 gmmutil          01139
11   01 gmmutil          01154
12   01 gmmutil          01172
13   01 gmmutil          01196
14   09 rrcllcp          16550
15   09 rrccspf          02198
16   27 rrccsp           20654
17   05 gsdi             09787
18   01 gsdi_co          01538
19   1C cnlbs            03307

OK
AT!GCDUMP
No crash data available

OK

#4

Upon closer inspection, it appears that the modem attempts only 3G connections, whereas my application (and my SIM cards, as far as I know) requires GSM for the improved coverage. Is there a way to set these modems to GSM-only mode?

I’ve attempted to send in a 0 AcT parameter to AT+COPS like so:

AT+COPS=4,2,"24004",0
OK

AT+COPS=3,0
OK
AT+COPS?
+COPS: 0,0,"SWEDEN",2
OK

AT+COPS=3,2
OK
AT+COPS?
+COPS: 0,2,"24004",2
OK

but this does not seem to change anything (in particular, the response to AT+COPS? still indicates an AcT of 2 meaning UTRAN).


#5

Hi,

To force both MC879x and MC870x to works in GSM only, please use !BAND command. Kindly query supported mode using “AT!BAND?” and refer to AT command document for usage.

As both MC8705 and MC8790 facing the same issue… I am guessing it may caused by the ARM system if you are using same platform to test, e.g. insufficient power.
Do you have chance to test both module using MC dev.kit with desktop PC running Windows or Linux?

Thx
L


#6

Running the modems in a laptop yields correct behaviour; No modem restarting.
I will continue troubleshooting with the ARM system manufacturer.

Thank you very much for your assistance!