using nRF9160 SLM

[sravan.rikka]

Hi Team,

Can you please provide your inputs here.

1. Is the nRF9160 SLM supports NIDD(non-ip data delivery)? If yes, can you please provide the AT commands to configure NIDD.

2. Is the  nRF9160 SLM MQTT supports TLS?

3. We have tried  nRF9160 SLM FOTA on nRF9160 DK board, it seems that FOTA upgrade is happening on external Flash and in next power cycle it is copying from external Flash to internal Flash. Is that my understanding correct? Is the external Flash is mandatory for the FOTA? Can't we upgrade the internal Flash directly through FOTA?

Regards,

Sravan Rikka

[Charlie]

Hi Sravan,

• 1 - Start FOTA for application update.

• 2 - Start FOTA for modem delta update.

• 3 - Start FOTA for full modem update. Can only be used when the overlay-full_fota.conf configuration file is used.

1. For op=1, you are correct.

2. For op=2, you are half correct. It only does Modem delta upgrades, no SLM application firmware upgrade. You can refer to this page about modem delta upgrade: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.6.0/nrf/libraries/dfu/dfu_target.html#modem-delta-upgrades

3. For op=3, you are wrong. It only does full modem update, no SLM application firmware upgrade. https://developer.nordicsemi.com/nRF_Connect_SDK/doc/2.6.0/nrf/libraries/dfu/dfu_target.html#full-modem-upgrades

4. Yes, you are correct.

5. The full modem firmware data will be downloaded and stored in external flash first, then loaded from external flash to internal modem's flash.

Best regards,

Charlie

[sravan.rikka]

Thank you for the quick response.

4. In case of op=1 or op=2, after upgrade we have to reset the nrF9160 MCU to reflect the upgrades, am I correct?

[Charlie]

You can disable the external flash in device tree or simply remove it, but the source codes already self explained how external flash is used, I wonder why you need to confirm.

Best regards,

Charlie

[sravan.rikka]

Thank you for the clarification.

1. What is the maximum payload we can send using MQTT?

2. Under "nrf9160_at_commands_v2.4" doc I couldn't find the MQTT related AT commands, where can I get it?

I got it at below path.

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/applications/serial_lte_modem/doc/MQTT_AT_commands.html

And tried communicating with MQTT commands.

When I send AT#XMQTTCFG=\"sravan/clientid\",60,0 , got ERROR response. Then thought to test read command then tried AT#XMQTTCFG? and got ERROR response. Why nRF9160 is giving error response for read command as well? am I missing anything.

[Charlie]

Hi Sravan,

1. See https://devzone.nordicsemi.com/f/nordic-q-a/101645/mqtt-publish-max-size/435465

2. See Serial LTE modem — nRF Connect SDK 2.6.0 documentation (nordicsemi.com). SLM support two type of AT commands.

• Modem-specific AT commands - nRF91x1 AT Commands Reference Guide and nRF9160 AT Commands Reference Guide

• Proprietary AT commands - SLM-specific AT commands

About the MQTTCFG error, could you test with the nRF Connect for Desktop->Serial Terminal app and show me the log?

Best regards,

Charlie

[sravan.rikka]

1. We are using mosquito broker then can I publish 256MB of data using MQTT  AT command? Will the nRF9160 sends out 256MB of data in single shot?

2. Please see the screenshot of Desktop->Serial Terminal app.

Fullscreen show log.txt Download

12:54:57.699	Initialising nrfutil module: device
12:54:59.507	Using nrfutil-device core version: 7.7.1
12:55:00.190	Using nrfutil-device version: 2.1.1
12:55:00.190	Using nrf-device-lib version: 0.17.5
12:55:00.190	Using nrfjprog DLL version: 10.24.0
12:55:00.190	Using JLink version: JLink_V7.94e
12:55:00.246	Device Connected SN:000960014654
12:55:00.246	Getting serialport options from persistent store 000960014654.pc-nrfconnect-serial-terminal
12:55:00.247	Device Connected SN:null
12:55:08.919	Selected device with s/n 000960014654
12:55:08.925	Opened port with options: {"baudRate":115200,"dataBits":"8","stopBits":"1","parity":"none","rtscts":false,"path":"COM17"}
12:55:08.940	Get terminal settings from persistent store 000960014654.vCom-0.TerminalSettings
12:55:54.286	Closed port: COM17
12:55:55.641	Opened port with options: {"baudRate":115200,"dataBits":"8","stopBits":"1","parity":"none","rtscts":false,"path":"COM17"}
12:55:55.661	Get terminal settings from persistent store 000960014654.vCom-0.TerminalSettings

[Charlie]

sravan.rikka said:

1. We are using mosquito broker then can I publish 256MB of data using MQTT  AT command? Will the nRF9160 sends out 256MB of data in single shot?

According to RE: MQTT Publish Max size, 
For MQTT publishing, MQTT messages can be divided into several TCP packages, so the limitation is mainly how much data datamode can receive before sending the MQTT message out, and it is 4KB(decided by datamode ring buffer size UART_DATA_SIZE 4096).

so you cannot. On MQTT protocol level, it sends in a single shot. On TCP protocol level, it fragments big MQTT message in to small TCP packets to send out.

sravan.rikka said:

2. Please see the screenshot of Desktop->Serial Terminal app.

There is no command with format "AT+XMQTTCON?" in MQTT client AT commands — nRF Connect SDK 2.6.0 documentation (nordicsemi.com). Do you mean "AT#XMQTTCON?"?

Best regards,

Charlie

[sravan.rikka]

1. I didn't get it clearly. I want to publish 256MB of data to Mosquito broker. Can I send 256MB using this publish command AT#XMQTTPUB=\"sravan/mqtttopic\","Hi How are you ------------------------(256MB of data)",1,0.

2. No, I mean AT#XMQTTCFG? itself giving ERROR. Please see below screenshot. For your information, I can able to make call using TCP commands but MQTT read command itself is not working, I mean giving ERROR response. Do I need to configure anything to enable the MQTT feature?

3. How do I need to know that MQTT is enabled in that SLM nRF9160?