question on serial_lte_modem sample

[Siyou]

Hi 

I am evaluating the serial_lte_modem sample with pc as client but failed, could you share the cmd format for gps start function?

here is the log after I issued the xgpsrun cmd as: 

AT#XGPSRUN=1

*** Booting Zephyr OS build v2.0.99-ncs1-rc1-1162-g9a0a85cf6760  ***
[00:00:01.548,095] <inf> app: Serial LTE Modem
[00:00:06.143,280] <err> gps: Failed to set fix retry value (err: -14)
[00:00:06.143,280] <err> gps: GPS start failed: -1

[Siyou]

Hi,

Here we have another question about the GPS cold/hot start:

After GPS fixed successfully, we found the gps was cold start(TTFF is about 30s~50s) after applying a software reset without power cycle? 

According to the definition of delete_mask in nrf_socket.h, we thought it should be hot start when we set the delete_mask=0, but it was not, why the GPS needs to re-search even we have not deleted the data in NV? 

/**@brief Defines a mask of non-volatile data types to delete.
 * @details
 *          - Bit 0 denotes ephemerides data.
 *          - Bit 1 denotes almanac data (excluding leap second and ionospheric correction parameters).
 *          - Bit 2 denotes ionospheric correction parameters data.
 *          - Bit 3 denotes last good fix (the last position) data.
 *          - Bit 4 denotes GPS time-of-week (TOW) data.
 *          - Bit 5 denotes GPS week number data.
 *          - Bit 6 denotes leap second (UTC parameters) data.
 *          - Bit 7 denotes local clock (TCXO) frequency offset data.
 */
typedef uint32_t nrf_gnss_delete_mask_t;

[Heidi]

Hi, the simple GPS function in this example does a cold start by nature. A hot start, like in the asset_tracker sample, has not been taken into consideration, unfortunately.

[Siyou]

Hi Heidi,

Sorry, one more question to this sample:
In our test, I found the SYSTEMMODE was 0,0,1,0 after the initialization finished, even without issue the cmd "AT%XSYSTEMMODE=0,0,1,0"
Moreover, I issued AT%XSYSTEMMODE=0,0,0,0, then reboot nrf9160 and check the SYSTEMMODE still was 0,0,1,0.
I want to know when and where to set the SYSTEMMODE to 0,0,1,0 during the sample initialization, and how to disable it?

Thanks!

[Heidi]

Hi, you can only set SYSTEMMODE when the modem is in offline mode, so run AT+CFUN=4 before setting the system mode. 

[Siyou]

Hi Heidi,

Yes I knew the SYSTEMMODE can be modified when CFUN=0 or CFUN=4.
My question is why the SYSTEMMODE default value is 0,0,1,0 but not 0,0,0,0 in serial_lte_modem sample, and how to change its default value to 0,0,0,0 without issue AT cmd?

Thanks.