MC7455 GPS not functioning

IoT Modules MC/EM Series
1

Hi,

Currently I am trying to get GPS messages (NMEA) through MC7455 module. After powering up the module I have three ttyUSB interfaces. If I understood correctly ,
ttyUSB0 --> is for diagnostic functionalities
ttyUSB1 --> is for GPS
ttyUSB2 --> is for sending AT commands.

I tried seeing the output of /dev/ttyUSB1 through minicom, I didn’t see any NMEA messages. So,I tried to configure the GPS through AT commands

I used the following commands:
AT!ENTERCND=“A710”
OK
at!custom?
!CUSTOM:
GPSENABLE 0x01
GPSLPM 0x01
IPV6ENABLE 0x01
SIMLPM 0x01
USBSERIALENABLE 0x01
SINGLEAPNSWITCH 0x01
OK
at!gpstrack?
ERROR
at!gpstrack=1,255,1000,30,1
ErrCode = 15
OK

After running the at command gpstrack I am getting the error code:15 which means error in fix. What should I do to get the NMEA messages.

Thanks & regards,
vinothkumar

2

Hello,

I’ve EM7455 installed on DELL Latitude E7270 running dual boot (Ubuntu 17.04 and Windows 10 PRO 64 bit). I’ve tested your commands through Windows 10 via HyperTerm and found out no errors with "AT!GPSTRACK=1,255,1000,30,1 as below:

ati
Manufacturer: Sierra Wireless, Incorporated
Model: EM7455
Revision: SWI9X30C_02.24.03.00 r6978 CARMD-EV-FRMWR2 2017/03/02 13:36:45
MEID: 35432407003509
IMEI: 354324070035098
IMEI SV: 9
FSN: LF618304770110
+GCAP: +CGSM

at!gpstrack=?
!GPSTRACK: ,,,,
: 1-Standalone, 2-MS-Based, 3-MS-Assisted
: 1-255 seconds
: 1-4294967280 meters
: 1-1000,1000=continuous
: 1-65535 seconds

OK
at!gpstrack=1,255,1000,30,1
OK
at!gpsstatus?
Current time: 1980 01 06 6 00:32:01

1980 01 06 6 00:00:00 Last Fix Status = FAIL, FAILCODE = 0
1980 01 06 6 00:31:49 Fix Session Status = ACTIVE

No TTFF available

OK
at!gpsstatus?
Current time: 2017 09 12 1 15:06:47

2017 09 12 1 15:06:46 Last Fix Status = SUCCESS
2017 09 12 1 15:06:46 Fix Session Status = ACTIVE

Which current firmware level of your MC7455 ? Believe your MC7455 should be flashed with latest firmware.

3

Hi,

I also have flashed the same firmware to my system.

AT+GMR
SWI9X30C_02.24.03.00 r6978 CARMD-EV-FRMWR2 2017/03/02 13:36:45

But still I am getting the same error.

at!custom?
!CUSTOM:
GPSENABLE 0x01
GPSLPM 0x01
IPV6ENABLE 0x01
SIMLPM 0x01
USBSERIALENABLE 0x01
SINGLEAPNSWITCH 0x01

at!gpstrack=1,255,1000,30,1
ErrCode = 15
OK

at!gpsstatus?
Current time: 1980 01 06 6 00:02:23
1980 01 06 6 00:02:23 Last Fix Status = NONE
1980 01 06 6 00:02:23 Fix Session Status = NONE
No TTFF available
OK

at!gpsstatus?
Current time: 1980 01 06 6 00:02:33
1980 01 06 6 00:02:33 Last Fix Status = NONE
1980 01 06 6 00:02:33 Fix Session Status = NONE
No TTFF available
OK

at!gpstrack=1,255,1000,30,1
ErrCode = 15
OK

Thanks & regards,
Vinothkumar

1 Like
4

Hello,

If not mistaken, if you would like to access that MC7455 on Linux/Ubuntu via minicom should be through “/etc/ttyUSB2” and make sure “modemmanager” is stopped. Could you try again.

5

Hello,

I’ve MC7455 module installed on DELL E7240 running Ubuntu 17.04 and finished all required Sierra QMI drivers. I’ve tested as you’ve been done where result as below:

Welcome to minicom 2.7

OPTIONS: I18n
Compiled on Feb 7 2016, 13:37:27.
Port /dev/ttyUSB2, 17:00:14

Press CTRL-A Z for help on special keys

Manufacturer: Sierra Wireless, Incorporated
Model: MC7455
Revision: SWI9X30C_02.24.03.00 r6978 CARMD-EV-FRMWR2 2017/03/02 13:36:45
MEID: 35907206052419
IMEI: 359072060524192
IMEI SV: 9
FSN: LQ652445790310
+GCAP: +CGSM

OK
atz
OK
at!entercnd=“A710”
OK
at!gpstrack=1,255,1000,30,1
OK
at!gpsstatus?
Current time: 1980 01 06 6 00:05:28

1980 01 06 6 00:05:28 Last Fix Status = NONE
1980 01 06 6 00:05:14 Fix Session Status = ACTIVE

No TTFF available

OK
at!gpsstatus?
Current time: 1980 01 06 6 00:05:36

1980 01 06 6 00:05:36 Last Fix Status = NONE
1980 01 06 6 00:05:14 Fix Session Status = ACTIVE

No TTFF available

OK

Believe our “expert” members could give another input.

6

Set GPSLPM = 0
Otherwise, unless you have an active connection, the GPS will go into LPM

“GPSLPM”—Enable/disable GPS in Low Power Mode.
:
• 0 = Enable—GPS engine remains enabled when modem enters LPM
(Default)
• 1 = Disable—GPS engine is disabled when modem enters LPM

7

Hi,

Ya. Thank you after seting low power mode active it worked.

AT!CUSTOM=“GPSENABLE”,1
AT!CUSTOM=“GPSLPM”,0
AT!RESET

and to see the NMEA messages on /dev/ttyUSB1 port we need to send the following message:

echo $GPS_START > /dev/ttyUSB1

Regards,
Vinoth

8

I just want to add to this the AT Manual (Rev. 3) states “0” (enabled) is the default mode.

“GPSLPM”—Enable/disable GPS in Low Power Mode.
<value>:
• 0 = Enable—GPS engine remains enabled when modem enters LPM
(Default)
• 1 = Disable—GPS engine is disabled when modem enters LPM

It does not appear to be correct as it seems “1” (disabled) is the default mode.

9

What makes you think 1 is the default, if it says 0 is the default in the manual as you stated?..