using nRF9160 SLM

RE: using nRF9160 SLM

Charlie — Fri, 03 May 2024 13:39:06 GMT

Hi Sravan,

1)Yes, 2) No.

The buffer will be clean up and reused by next publish action.

Best regards,

Charlie

RE: using nRF9160 SLM

sravan.rikka — Tue, 30 Apr 2024 12:39:06 GMT

Hi Charlie,

Can you please respond, I am awaiting for your comments.

1. CONFIG_SLM_MQTTC_MESSAGE_BUFFER_LEN=512. For example if we want to publish 4KB of data, can we publish 512 bytes 8(4KB/512) times as below? I mean connect one time and publish 8 consecutive packets?

AT#XMQTTCFG=\"sravan/clientid\",60,0
AT#XMQTTCON=1,"","",\"192.168.0.102\",1883
AT#XMQTTPUB=\"sravan/mqtttopic\","1. Hi How are you…......(512 bytes)",1,0
AT#XMQTTPUB=\"sravan/mqtttopic\","2. Hi How are you…......(512 bytes)",1,0
		.
		.
		.
		.
AT#XMQTTPUB=\"sravan/mqtttopic\","7. Hi How are you…......(512 bytes)",1,0
AT#XMQTTPUB=\"sravan/mqtttopic\","8. Hi How are you…......(512 bytes)",1,0
AT#XMQTTCON=0

2. OR Do we need to config, connect, publish and disconnect for every 512 bytes as below?

AT#XMQTTCFG=\"sravan/clientid\",60,0
AT#XMQTTCON=1,"","",\"192.168.0.102\",1883
AT#XMQTTPUB=\"sravan/mqtttopic\","1. Hi How are you…......(512 bytes)",1,0
AT#XMQTTCON=0


AT#XMQTTCFG=\"sravan/clientid\",60,0
AT#XMQTTCON=1,"","",\"192.168.0.102\",1883
AT#XMQTTPUB=\"sravan/mqtttopic\","2. Hi How are you…......(512 bytes)",1,0
AT#XMQTTCON=0
		.
		.
		.
		.
		.
		.
		.
		.
		.
AT#XMQTTCFG=\"sravan/clientid\",60,0
AT#XMQTTCON=1,"","",\"192.168.0.102\",1883
AT#XMQTTPUB=\"sravan/mqtttopic\","7. Hi How are you…......(512 bytes)",1,0
AT#XMQTTCON=0


AT#XMQTTCFG=\"sravan/clientid\",60,0
AT#XMQTTCON=1,"","",\"192.168.0.102\",1883
AT#XMQTTPUB=\"sravan/mqtttopic\","8. Hi How are you…......(512 bytes)",1,0
AT#XMQTTCON=0

Regards,

Sravan Rikka

RE: using nRF9160 SLM

Charlie — Tue, 30 Apr 2024 07:36:10 GMT

No, the maximum limitation is nRF9160 RAM size, which is 256KB. You can always allocate a biggerbuffer that is not used by the application at build time as long as region `RAM' is not overflowed.

Best regards,

Charlie

RE: using nRF9160 SLM

sravan.rikka — Mon, 29 Apr 2024 10:09:27 GMT

Hi Charlie,

1. If I want to increase buffer size as CONFIG_SLM_MQTTC_MESSAGE_BUFFER_LEN=65535. Can I increase to 65535, is there any limitation? What is the maximum allowed buffer size?

2. In data mode maximum CONFIG_SLM_DATAMODE_BUF_SIZE=4096, Is it possible to increase this buffer size to 65535? Is there any limitation? What is the maximum allowed buffer size?

Regards,

Sravan Rikka

RE: using nRF9160 SLM

Charlie — Mon, 29 Apr 2024 09:54:21 GMT

1. Yes, with default SLM.

2.No. I assume you mean command "#XTCPSEND[=<data>]" by saying "TCP mode".

See document: TCP and UDP AT commands — nRF Connect SDK 2.6.0 documentation (nordicsemi.com)

The <data> parameter is a string that contains the data to be sent. The maximum size of the data is 1024 bytes. When the parameter is not specified, SLM enters slm_data_mode.

In normal mode, the maximum data size you can send is decided by SLM_MAX_PAYLOAD_SIZE=1024.

In data mode, the maximum data size you can send is controlled by CONFIG_SLM_DATAMODE_BUF_SIZE, which is 4096 bytes.

Best regards,

Charlie

RE: using nRF9160 SLM

sravan.rikka — Mon, 29 Apr 2024 09:10:04 GMT

1. It is clear that we can publish only 512 bytes in one call using MQTT. If we want to publish 2048 bytes, we have to make 4 MQTT calls, am I correct?

2. In TCP mode also we can transfer 512 bytes maximum in a TCP call?

RE: using nRF9160 SLM

Charlie — Fri, 26 Apr 2024 08:51:13 GMT

Hi Sravan,

I did further check with the SLM codes, and figure the smallest limitation is actually not 4K from UART buffer, but CONFIG_SLM_MQTTC_MESSAGE_BUFFER_LEN, which is 512 bytes.

1. 64KB is still quite big. Yes, you can fragment and reassembly 64KB data into small pieces on application layer and send through MQTT.

2. It is possible, you need to modify the current SLM and do more exploration. At least the following configurations need to pay attention. No AT command can simply do such modification.

CONFIG_SLM_DATAMODE_BUF_SIZE=4096

CONFIG_SLM_MQTTC_MESSAGE_BUFFER_LEN=512

3. For the current SLM implementation, you can only send 512 byte size message.

Best regards,

Charlie

RE: using nRF9160 SLM

sravan.rikka — Thu, 25 Apr 2024 08:57:11 GMT

Hi Charlie,

I am not sending 256MB but want to understand how nRF9160 behaves or limitations when I send more data like 256MB.

As per my application, I want to send 64KB of data. Can you please answer now? for my below queries.

1. If we want to publish 64KB of data, do we need to publish multiples of 4KB? or Can I send 64KB in single publish?

64B/4KB=16 times we have to publish 4KB data?

AT#XMQTTPUB=\"sravan/mqtttopic\"," 1 Hi How are you........ (Assume it is 4KB)"

AT#XMQTTPUB=\"sravan/mqtttopic\"," 2 Hi How are you........ (Assume it is 4KB)"

AT#XMQTTPUB=\"sravan/mqtttopic\"," 3 Hi How are you.......... (Assume it is 4KB)"

AT#XMQTTPUB=\"sravan/mqtttopic\"," 15 Hi How are you....... (Assume it is 4KB)"

AT#XMQTTPUB=\"sravan/mqtttopic\"," 16 Hi How are you....... (Assume it is 4KB)"

2. is there any possibility to modify the message size more than 4KB? If yes, can you please tell the the AT command?

3. Only 4KB of data can be published per call? If I want publish16KB, then I have to do 4 calls?

Please provide your comments.

Regards,

Sravan Rikka

RE: using nRF9160 SLM

Charlie — Thu, 25 Apr 2024 08:18:24 GMT

Hi Sravan,

Just wonder could you explain more about your application? Why you need to send 256MB data with MQTT through Cellular IoT network?

This is not a usual choice. Here are some of the reasons.

1. Cellular IoT like NB-IoT/LTE-M are very slow compared with other LTE technologies like 4G, 5G. It is designed for simple IoT sensor data transmission.

2. MQTT is also designed for message transmission, so MQTT/TCP over Cellular IoT will make the data transmission even more slow.

3. 256MB is a very big file in IoT world. If you use the most common LTE-M relase13 Uplink peak rate 1 Mbit/s, it will take more than half one hour. It is no surprise it will take more time when retransmission happens on different layers LTE-M/IP/TCP/MQTT.

I suggest you read about the white paper <Best practices for cellular IoT development> before you decide to move forward.

You can also try to contact with our local sales and FAE team about your project to get more onsite help. Contact us - nordicsemi.com

Best regards,

Charlie

RE: using nRF9160 SLM

sravan.rikka — Tue, 23 Apr 2024 09:24:42 GMT

Can you please respond for below queries.

1. If we want to publish 256MB of data, do we need to publish multiples of 4KB?

256MB/4KB=65536 times we have to publish 4KB data?

AT#XMQTTPUB=\"sravan/mqtttopic\"," 1 Hi How are you........ (Assume it is 4KB)"

AT#XMQTTPUB=\"sravan/mqtttopic\"," 2 Hi How are you........ (Assume it is 4KB)"

AT#XMQTTPUB=\"sravan/mqtttopic\"," 3 Hi How are you.......... (Assume it is 4KB)"

AT#XMQTTPUB=\"sravan/mqtttopic\"," 65535 Hi How are you....... (Assume it is 4KB)"

AT#XMQTTPUB=\"sravan/mqtttopic\"," 65536 Hi How are you....... (Assume it is 4KB)"

2. is there any possibility to modify the message size more than 4KB? If yes, can you please tell the the AT command?

RE: using nRF9160 SLM

Charlie — Tue, 23 Apr 2024 09:11:19 GMT

1. No, the message size is limited to 4KB with Serial LTE Modem default configuration.

2. I am traveling so not able to do a test, but I do have some suggestion for you to check. First, you have to make sure the LTE connection is built before using MQTT, this can be checked with "AT+CEREG?" or use "AT+CEREG=5" to enable notification before "AT+CFUN=1". Second, I think it is not necessary to add "\" before ", just use the commands as the examples.

3. If it enabled correctly, it will work.

I will give it a try later and update you the log.

Best regards,

Charlie

RE: using nRF9160 SLM

sravan.rikka — Fri, 19 Apr 2024 13:16:38 GMT

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?

RE: using nRF9160 SLM

Charlie — Fri, 19 Apr 2024 11:05:07 GMT

[quote user="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?[/quote]

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.

[quote user="sravan.rikka"]2. Please see the screenshot of Desktop->Serial Terminal app.[/quote]

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

RE: using nRF9160 SLM

sravan.rikka — Fri, 19 Apr 2024 08:43:55 GMT

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.

devzone.nordicsemi.com/.../show-log.txt

RE: using nRF9160 SLM

Charlie — Thu, 18 Apr 2024 16:22:46 GMT

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

RE: using nRF9160 SLM

sravan.rikka — Thu, 18 Apr 2024 09:48:27 GMT

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.

RE: using nRF9160 SLM

Charlie — Tue, 16 Apr 2024 10:43:21 GMT

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

RE: using nRF9160 SLM

sravan.rikka — Mon, 15 Apr 2024 10:45:27 GMT

Thank you very much for the clarifications.

4. In case of op=1 or op=2, after upgrading how do I need to confirm that it is upgraded in internal Flash only.

RE: using nRF9160 SLM

Charlie — Mon, 15 Apr 2024 10:36:02 GMT

Yes, you are correct.

RE: using nRF9160 SLM

sravan.rikka — Mon, 15 Apr 2024 09:26:41 GMT

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?

RE: using nRF9160 SLM

Charlie — Mon, 15 Apr 2024 09:21:51 GMT

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

RE: using nRF9160 SLM

sravan.rikka — Fri, 12 Apr 2024 12:36:29 GMT

Radio Firmware means mfw.

Can you please answer to below 5 queries.

1. When we select op=1, it will upgrade the SLM application firmware only, am I correct?

2. When we select op=2, it will upgrade the mfw firmware only, am I correct?

3. When we select op=3, it will upgrade both SLM application firmware and mfw firmware, am I correct?

4. When we select op=1 o op=2, the firmware upgrade will happen in internal Flash, am I correct?

5. When we select op=3, the firmware upgrade will happen in external Flash, am I correct?

RE: using nRF9160 SLM

Charlie — Fri, 12 Apr 2024 10:52:05 GMT

Hi Sravan,

I am not sure which kind of Radio Firmware you mean here. Do you mean MFW(modem firmware) running in net core?

If yes, you can update either application firmware or MFW according to your needs separately. For examples, if critical bugs fix or new features are added.

op=0 do not support resume. All the ops actions can be checked in SLM source code, or you can simply do some tests to make sure they work as you expect.

https://github.com/nrfconnect/sdk-nrf/blob/25f99408c28f9a212571024be0cb815256474c54/applications/serial_lte_modem/src/slm_at_fota.c#L296

Feel free to check with me if you have any new questions.

Best regards,

Charlie

RE: using nRF9160 SLM

sravan.rikka — Fri, 12 Apr 2024 05:45:26 GMT

Thank you for the clarification. now, NIDD is clear to me.

3. We have SLM application firmware and Radio Firmware, both we have to upgrade right?

AT#XFOTA=<op>[,<file_url>[,<sec_tag>[,<pdn_id>]]]

0 - Stop FOTA (during download only). Can be used as a way to pause and resume the download, by issuing the same FOTA start command to resume.
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.

When we select op=1, it will upgrade the SLM application firmware only, am I correct?

When we select op=2, it will upgrade the Radio firmware only, am I correct?

When we select op=3, it will upgrade both SLM application firmware and Radio firmware, am I correct?

RE: using nRF9160 SLM

Charlie — Thu, 11 Apr 2024 13:48:54 GMT

Here you can find the latest AT Commands document https://docs.nordicsemi.com/bundle/ref_at_commands/page/REF/at_commands/packet_domain/cgdcont_set.html

Yes, your understanding is correct.