I installed Cayenne on R-Pi3+ and it was magic. I found that I could login to my Cayenne web account and there was my R-Pi dashboard with various display widgets, including an existing DS18B20 (digital temperature sensor).
My question now is how to read the DS18B20 with MQTT. I suppose I should also ask about MQTT with the other widgets that you see there, such as network speed. How are these values sent to the Cayenne dashboard? I’m beginning to suspect they are not published by MQTT.
I had previously installed the temp sensor to r-pi using modprobe w1-therm. This creates a permanent device at /sys/bus/w1/devices/28-000007a89399. The device apparently can be polled to write the current temperature into a file.
I also have a DHT22 temp and humidity sensor. This device was not installed as a system device. I have used the Adafruit_Python_DHT software and cayenne.client to publish MQTT messages for it. I then created a Cayenne dashboard for it.
I have also written a Python client to subscribe to DHT22 messages from my Cayenne-MQTT publisher. So, I’ve made a lot of progress in understanding this stuff.
But my question remains: how does the DS18B20 data get to Cayenne dashboard? Is MQTT involved? Do I need to write more code for MQTT publish of the DS18B20 if I want to subscribe from other clients?
I hope I’ve been clear enough. Thanks for your help.