Need help connecting to MQTT using nRF9160

[pranav-ether]

I can't figure out what I'm missing. I'm not able to send messages using MQTT.

Here's the link to my code: https://github.com/pranav-ether/test/tree/main/mqtt_pub

This are the logs:

[00:02:58.031,768] <inf> LTE: Network registration status: Connected - home network
[00:02:58.031,890] <inf> LTE: Connected to LTE network
[00:02:58.031,921] <inf> LTE: ====== Cell Network Info ======
[00:02:58.033,477] <inf> LTE: Signal strength: 42
[00:02:58.034,210] <inf> LTE: Current LTE band: 8
[00:02:58.034,912] <inf> LTE: Supported LTE bands: (1,2,3,4,5,8,12,13,17,19,20,25,26,28,66)
[00:02:58.035,705] <inf> LTE: Tracking area code: 8CA1
[00:02:58.036,468] <inf> LTE: Current mode: 0
[00:02:58.037,200] <inf> LTE: Current operator name: 65501
[00:02:58.038,146] <inf> LTE: Cell ID of the device: 0E446D21
[00:02:58.039,337] <inf> LTE: IP address of the device: 100.67.202.179
[00:02:58.039,886] <inf> LTE: Modem firmware version: mfw_nrf9160_1.3.5
[00:02:58.040,618] <inf> LTE: LTE-M support mode: 0
[00:02:58.041,259] <inf> LTE: NB-IoT support mode: 1
[00:02:58.041,900] <inf> LTE: GPS support mode: 0
[00:02:58.042,633] <inf> LTE: Mobile network time and date: 24/08/13,06:33:37+08
[00:02:58.042,633] <inf> LTE: ===============================
[00:02:58.043,121] <inf> MQTT: Connection to broker using mqtt_init
[00:04:23.972,839] <err> mqtt_helper: Cloud MQTT keepalive ping failed: -128

[Charlie]

(+) How to Activate the nRF Cloud using Airtel M2M sim card? - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

(+) steps for lte registration. - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

(+) Verification failed - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com)

Mobile IoT Deployment Map | Internet of Things (gsma.com) shows only JIO supports NB-IoT in India. Please have a try with JIO NB-IoT network.

Best regards,

Charlie

[pranav-ether]

Airtel says that the SIMs they've sent are NB-IoT SIMs.
But this confirms that there is no Airtel signal right? Is there any other ways of pin pointing the issue?
I'm not able to fine LTE Link Monitor app on nRF Connect. Any idea why? I'm using Linux and the latest appimage.

mosh:~$ > at AT%COPS=?
at AT%COPS=?
%COPS: (1,"","","405861",9)
OK

Network registration status: searching
LTE cell changed: ID: -1, Tracking area: -1
Currently active system mode: NB-IoT
LTE cell changed: ID: 2894737, Tracking area: 49173
mosh:~$ > at AT%COPS=?
at AT%COPS=?
Currently active system mode: None
%COPS: (1,"","","405861",9)
OK

LTE cell changed: ID: -1, Tracking area: -1
RRC mode: Connected
Currently active system mode: NB-IoT
LTE cell changed: ID: 6032786, Tracking area: 49173
RRC mode: Idle
Modem domain event: Search done
mosh:~$ > at AT%COPS=?
at AT%COPS=?
Currently active system mode: None
%COPS: (3,"","","405861",9)
OK

LTE cell changed: ID: -1, Tracking area: -1

[Charlie]

Yes, only JIO network is found by your device according to AT%COPS=? feedback.

MCC	MNC	PLMN	Region	Country	ISO	Operator	Brand	TADIG	Bands
405	861	405861	Asia and the Middle East	India	IN	Karnataka	Jio	INDJ9	LTE 850 / LTE 1800 / TD-LTE 2300

[pranav-ether]

I was able to get Jio SIMs and I'm able to connect to the network. But my MQTT program still doesn't work. It works only for brokers without username & password. The broker I want to connect to has username, password & port (My program is in the body of this post).

Also the network is getting connected on the nRF9160DK but not my custom board. What could be the reason?

[Charlie]

1) For the original sample  docs.nordicsemi.com/.../description.html, if you want to use username & password to connect with MQTT broker, you need to add username & password parameters here:

https://github.com/nrfconnect/sdk-nrf/blob/2bae3437305bc8f5eb29260ca545fb8033b2b80b/samples/net/mqtt/src/modules/transport/transport.c#L187

struct mqtt_helper_conn_params {

/* The hostname must be null-terminated. */

struct mqtt_helper_buf hostname;

struct mqtt_helper_buf device_id;

struct mqtt_helper_buf user_name;

struct mqtt_helper_buf password;

};

2) For your custom board connection issue, can you attach the log and modem trace?