How to know if we have an IP address

[Depraz]

Hello,

I am using the modem callback:

typedef void(*lte_lc_evt_handler_t)(const struct lte_lc_evt *const evt);

To check if the modem is connected using the following code:

if evt->type == LTE_LC_EVT_NW_REG_STATUS
    isConnected = evt->nw_reg_status == LTE_LC_NW_REG_REGISTERED_HOME;

However, as far as I understood this only indicates that the modem radio is on, it does not indicate that the modem has an IP address and can connect to a server. To have this details, I need to use the AT command  CGPADDR.

Is there any way I can update the callback to make sure the modem got an IP address? I do not need to know which address it received.

Thanks

[Håkon Alseth]

Hi,

 

If you enable notifications in AT+CGEREP, you should get a notification when the default PDN connection has changed from the +CGEV notification:

https://infocenter.nordicsemi.com/topic/ref_at_commands/REF/at_commands/packet_domain/cgev.html?cp=2_1_6_2

 

Here's an example from at_client:

+CGEV: ME PDN ACT 0
+CGEV: IPV6 0

# manually querying
AT+CGDCONT?
+CGDCONT: 0,"IPV4V6","telenor.iot","10.x.y.z 1234:1234:1234::1234",0,0
OK

 

Kind regards,

Håkon

[Depraz]

Hello Håkon,

Thanks for your reply. I do not get how I can get this information in the callback

typedef void(*lte_lc_evt_handler_t)(const struct lte_lc_evt *const evt);

lte_lc_evt seems to give me only access to:

struct lte_lc_evt {
	enum lte_lc_evt_type type;
	union {
		enum lte_lc_nw_reg_status nw_reg_status;
		enum lte_lc_rrc_mode rrc_mode;
		struct lte_lc_psm_cfg psm_cfg;
		struct lte_lc_edrx_cfg edrx_cfg;
		struct lte_lc_cell cell;
	};
};

What would be the event type I should look for?

LTE_LC_EVT_NW_REG_STATUS
LTE_LC_EVT_PSM_UPDATE
LTE_LC_EVT_EDRX_UPDATE
LTE_LC_EVT_RRC_UPDATE
LTE_LC_EVT_CELL_UPDATE

Also, is there any higher level function that enables  AT+CGEREP, notifications?

[Håkon Alseth]

Hi,

 

Depraz said:

Thanks for your reply. I do not get how I can get this information in the callback

The lte_lc library unfortunately does not return CGEV notifications. I'll input this internally as a feature request. 

 

Depraz said:

Also, is there any higher level function that enables  AT+CGEREP, notifications?

 You can use the at_notif library and register your own handler specifically filtering for the +CGEV notifications:

#include <modem/at_cmd.h>
#include <modem/at_notif.h>

static void at_handler(void *context, const char *response)
{
	if (response == NULL) {
		printk("Response buffer is NULL-pointer");
		return;
	}
	const char * cgev_notification_filter = "+CGEV:";
	if (strncmp(cgev_notification_filter, response, strlen(cgev_notification_filter)) == 0) {
		printk("Match for +CGEV notification\n");
		printk("Received notification %s\n", response);
	}

}

/* Place these calls after bsdlib init, but before lte_lc_init_and_connect() */
err = at_notif_register_handler(NULL, at_handler);
if (err) {
	printk("Failed to initialize AT nofitication handler, err %d\n", err);
	return err;
}
err = at_cmd_write("AT+CGEREP=1", NULL, 0, NULL);
if (err) {
	printk("Unable to send AT command, err %d\n", err);
	return err;
}

 

I implemented the above simplistic filtering in https_client (ncs v1.4.2), here's a patch file:

cgev_notifications.patch

 

store this .patch file to ../path/to/ncs/nrf/ and apply it using git:

git apply cgev_notifications.patch

 

Here's the output from the sample:

*** Booting Zephyr OS build v2.4.0-ncs2  ***
HTTPS client sample started
Provisioning certificate
Waiting for network.. Match for +CGEV notification
Received notification +CGEV: ME PDN ACT 0

OK
Match for +CGEV notification
Received notification +CGEV: IPV6 0

Connecting to google.com
Sent 64 bytes
Received 892 bytes

>        HTTP/1.1 200 OK

Finished, closing socket.

 

Kind regards,

Håkon

[Depraz]

Thanks a lot Håkon!