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]

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

[sravan.rikka]

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?

[Charlie]

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

[sravan.rikka]

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