A-GPS download fails mid session

[MJD093]

Hello,

I am trying to run the A-GPS sample program but am encountering a bit of difficulty with the SUPL code.

I had to modify the LTE connection code to allow access for NB-IoT, APN and User/Pass for the SIMs we are using but encounter this error during the connection and download process:

New AGPS data requested, contacting SUPL server, flags 59
Established LTE link
ip 4a7d:8cc0:: (c08c7d4a) port 7276
Starting SUPL session
ULP encoding length: 38
Bytes sent: 38
Bytes received: 34
ULP ossDecode success, choice 3
SUPL server responded using version 2.0.4
SUPL response received
ULP encoding length: 57
Bytes sent: 57
read again
Bytes received: 708
ULP ossDecode more input 4
Bytes received: 2996
ULP ossDecode success, choice 5
Failed to send AGNSS data, type: 1 (err: 5)
UTC conversion/injection failed, rc: 3
Generic assistance data injection failed, rc: 3
SUPL error: 2
ULP encoding length: 34
Bytes sent: 34
SUPL session internal resources released
SUPL session finished
Done

While building the sample program, I also was warned about an error in the SUPL code:

[38/138] Building C object modules/nrf/lib/supl/CMakeFiles/..__nrf__lib__supl.dir/os/lte_params.c.obj
/Users/xxxxxx/Downloads/ncs/nrf/lib/supl/os/lte_params.c: In function 'parse_lte_mcc':
/Users/xxxxxx/Downloads/ncs/nrf/lib/supl/os/lte_params.c:73:3: warning: implicit declaration of function 'memset' [-Wimplicit-function-declaration]
   memset(lte->mcc, 0, 3);

Could I get a bit of help decyphering what went wrong here? I have made no modifications to the SUPL code and only added code to enable connection to the Network in my local area.

	static const char     at_commands_NB[][50]  = {
					AT_CFUN_OFF,
					AT_XSYSTEMMODE,
	#ifdef CONFIG_BOARD_NRF9160_PCA10090NS
					AT_MAGPIO_LTE,
					AT_BANDLOCK,
					AT_APN,
					AT_USER_PASS,
	#endif
					AT_ACTIVATE_LTE
				};
				
*********************************

static int activate_lte(bool activate)
{
	if (activate) {
		for (int i = 0; i < ARRAY_SIZE(at_commands_NB); i++) {

			if (at_cmd_write(at_commands_NB[i], NULL, 0, NULL) != 0) {
				printk("Error with at_commands_NB\n");
				return -1;
			}
		}

The above should be working correctly if the device was able to connect to the SUPL library in the first place so I doubt it's the above changes.

Many thanks,

MJD

[Simonr]

Hi

I've forwarded this issue internally to confirm whether this might be due to TCP not cooperating with NB-IoT or not (and hopefully find a fix or workaround to this issue). Please note that we are moving into the summer vacation period here in Norway, so it might take a bit longer to get to the bottom of this than expected, as staff during the month of July will be reduced. I'm sorry about the inconvenience, but please be patient. And I'll get back to you as soon as I hear something from the devs.

Best regards,

Simon

[MJD093]

Thank you Simonr

[MJD093]

Hi Simonr,
Has any progress been made internally on this issue?

Michael

[Hakon]

Hello,

not Simon, but I'm handling the case while he is away. Those that were working on your problem are on vacation now, so I got someone else to take over. Hopefully you will get an answer today or in the near future.

[Hakon]

Are you using the newest version of A-GPS sample? There seems to be an issue with A-GPS injection possibly being intercepted by GNSS search. Can you please capture a modem log? Just follow these instructions.

[MJD093]

I was using the SDK v1.2.0 to do this testing. I have updated to v1.3.0 and attached a modem trace below. Please let me know if there are any issues with the trace.

trace-2020-07-16T12-32-27.611Z.bin

For reference, the GPS application is modified to use an AT command array with the following commands, without this LTE set-up, the SIM Cards will never make a connection to the network.

#define AT_CFUN_OFF						"AT+CFUN=4"
#define AT_APN_zzzz					"AT+CGDCONT=0,\"IP\",\"ep.inetd.gdsp\""
#define AT_MAGPIO_LTE      			    "AT\%XMAGPIO=1,1,1,1,5,791,849"
#define AT_BANDLOCK						"AT\%XBANDLOCK=1,\"10000000000000000000\""
#ifdef CONFIG_BOARD_NRF9160DK_NRF9160NS
	#define AT_MAGPIO                   "AT\%XMAGPIO=1,0,0,1,1,1574,1577"
	#define AT_COEX0                    "AT\%XCOEX0=1,1,1570,1580"
	#define AT_APN_xxx				"AT+CGDCONT=0,\"IP\",\"xxx.com\""
	#define AT_xxxx_USER_PASS		"AT+CGAUTH=0,\"PAP\",\"xxx\",\"xxx\""
	#define AT_LEG_PCO					"AT\%XEPCO=1"
#endif

static const char     at_commands_NB[][50]  = {
				AT_CFUN_OFF,
				AT_XSYSTEMMODE,
#ifdef CONFIG_BOARD_NRF9160DK_NRF9160NS
				//AT_MAGPIO_LTE,
				AT_BANDLOCK,
				AT_APN_xxx,
				AT_xxx_USER_PASS,
				AT_LEG_PCO,
#endif
				AT_ACTIVATE_LTE
			};
			
static int activate_lte(bool activate)
{
	if (activate) {
		for (int i = 0; i < ARRAY_SIZE(at_commands_NB); i++) {
			if (at_cmd_write(at_commands_NB[i], NULL, 0, NULL) != 0) {
				printk("Error with at_commands_NB\n");
				return -1;
			}
		}

		at_notif_register_handler(NULL, wait_for_lte);
		if (at_cmd_write("AT+CEREG=2", NULL, 0, NULL) != 0) {
			printk("Error with wait_for_lte 1\n");
			return -1;
		}

		k_sem_take(&lte_ready, K_FOREVER);

		at_notif_deregister_handler(NULL, wait_for_lte);
		if (at_cmd_write("AT+CEREG=0", NULL, 0, NULL) != 0) {
			printk("Error with wait_for_lte 2\n");
			return -1;
		}
	} else {
		if (at_cmd_write(AT_DEACTIVATE_LTE, NULL, 0, NULL) != 0) {
			printk("Error with AT_DEACTIVATE_LTE\n");
			return -1;
		}
	}

	return 0;
}

I have tried with and without setting legecy PCO on v1.3.0 as mentioned to try by Simonr in an earlier reply and had no success.

Note:

I have had a couple instances today of this:

New AGPS data requested, contacting SUPL server, flags 59
Sending AT command: AT+CFUN=4
Sending AT command: AT%XSYSTEMMODE=0,1,1,0
Sending AT command: AT%XBANDLOCK=1,"10000000000000000000"
Sending AT command: AT+CGDCONT=0,"IP","xxx.com"
Sending AT command: AT+CGAUTH=0,"PAP","xxx","xxx"
Sending AT command: AT%XEPCO=1
Sending AT command: AT+CFUN=21
Established LTE link
ip 40e9:a6c0::1001:300:1b00:1b00 (c0a6e940) port 7276
Starting SUPL session
ULP encoding length: 38
Bytes sent: 38
read again
read again
read again
read error: -1
SUPL error: 1
ULP encoding length: 18
Sending SUPL message failed, bytes_sent: -1
SUPL session internal resources released
Done
Failed to start GPS

The last line of GPS failure to start is appearing in the v1.3.0 example, I not sure why but I have played around in the AT client and can see that swapping between AT+CFUN=21 and 31 can ERROR out so I believe that may be the issue. Does the code call CFUN=20 correctly in the trace after A-GPS failure? GPS starts and works as normal when SUPL is not configured 'y' in the prj.conf