Sending MQTT messages via AT commands nRF9160

[Jonnaybb]

Hello!

We are trying to send MQTT messages to a hosted mosquito broker via AT commands using the nRF9160.

We are trying to avoid programming the nrf9160 chip, as we're using an ESP32 master to relay all commands via UART. Previously, we used PPPoS on another module, but it seems this module is not yet supported? The only other way we can think of, is sending the MQTT messages through HTTP, but having no luck applying any curl http headers.

An example of what we're doing with no luck is:

at#xsocket=3,1,1
#XSOCKET: 3,6
OK
at#xtcpconn=3,"node02.myqtthub.com",1883
#XTCPCONN: 1
OK
at#xtcpsend=3
>POST /login
Host: node02.myqtthub.com:1883
Content-Type: application/json
Content-Length: 92

{"clientId":"HQC-TEST-519","userName":"jonhqc","password":"test1234","cleanSession":"false"}

Which in my understanding is applying a rest api via http as in this guide - https://support.asplhosting.com/t/rest-api-to-manage-myqtthub-service/86

Is there a better approach here? Simplicity is key.

[Martin Lesund]

Hi Jonnay,
Please run the SLM from master branch and utilize the dedicated MQTT AT commands --> https://github.com/nrfconnect/sdk-nrf/tree/master/applications/serial_lte_modem#mqtt-at-commands 

(How to update to master:

cd ncs/nrf
git checkout master
git pull
west update

# then build the SLM application

[Jonnaybb]

This is great news - one problem, we're using the Nimbelink version with the nRF9160 - Do you have any knowledge how we can make this work, even if Nimbelink hasn't supported it yet on their Nano?

[Martin Lesund]

Hi Jonnay,
From what I've understood Nimblelink uses their own version similar to our SLM (?) 
Is it possible to program the Nimblelink?
You may need to contact their customer support about supporting MQTT AT commands.

Best regards,
Martin L.