Difference: Cayenne (1 vs. 3)

Revision 32019-05-28 - UliRaich

Line: 1 to 1
 
META TOPICPARENT name="AFNOGWorkshop2019"

Connecting to Cayenne

A Micropython class connecting to WiFi and subscribing to the myDevices MQTT broker

Line: 9 to 9
  In order to connect to myDevices Cayenne you need:
  • your WiFi SSID
Changed:
<
<
  • your "WiFi password
>
>
  • your WiFi password
 
  • the Cayenne credentials:
    • client name
    • user name
    • password
Changed:
<
<		The CayenneMQTTClient class has a begin method taking Cayenne username, password and client id as parameters. The ssid and wifiPassword have default values but can be specified as well. The begin method will first connect to WiFi and then connect to the MQTT broker at mqtt.mydevices.com. It then subscribes to the command topic such that cmd messages from Cayenne can be passed on to a callback routine registered by the user of the CayenneMQTTClient class. In case of a cmd message the required response message is sent automatically.
>
>		The CayenneMQTTClient class has a begin method taking Cayenne username, password and client id as parameters. The ssid and wifiPassword have default values but can be specified as well. The begin method will first connect to WiFi and then connect to the MQTT broker at mqtt.mydevices.com. It then subscribes to the command topic such that cmd messages from Cayenne can be passed on to a callback routine registered by the user of the CayenneMQTTClient class. In case of a cmd message, the required response message is sent automatically.
 
Changed:
<
<		If the OLED display is connected the state of network connection will be shown.
>
>		If the OLED display is connected, the state of network connection will be shown.
  The CayenneMQTTClient provides the following methods to publish measurement results:
Line: 33 to 33
 
  • digitalWrite(channel,value), value must be 0 or 1

Parsing of command messages

Changed:
<
<		The callback function gets a message, a tuple consisting of the topic and the payload, as parameter. This message must be parsed to extract the channel number and the value. The CayenneMessage class helps with this. Create a CayenneMessage object cayenneMsg with topic and payload (message[0] and message[1]) as parameters.
>
>		The callback function gets a message, a tuple consisting of the topic and the payload, as parameter. This message must be parsed to extract the channel number and the value. The CayenneMessage class helps with this. Create a CayenneMessage object cayenneMsg with topic and payload (message[0] and message[1]) as corresponding parameters.
  cayenneMsg.channel will then contain the channel number on which the command must be executed, cayenneMsg.value contains the value.

Revision 22019-05-17 - UliRaich

Line: 1 to 1
 
META TOPICPARENT name="AFNOGWorkshop2019"

Connecting to Cayenne

A Micropython class connecting to WiFi and subscribing to the myDevices MQTT broker

Changed:
<
<		Since every sensor node needs to first connect to WiFi and later subscribe to the MQTT broker at mqtt.mydevices.com I wrote a small micro Python class accomplishing these tasks. You will have to modify the code inserting:
>
>		Since every sensor node needs to first connect to WiFi and later subscribe to the MQTT broker at mqtt.mydevices.com. Unfortunately the
Cayenne-MQTT-Python library depends on the Eclipse Paho MQTT Python client library, which is not available in Micropython.

I therefore ported the code to the umqtt.simple MQTT client available in Micropython. The API is the same as in the standard Cayenne MQTT client, which means that the example programs provided in this library will work without modification.

In order to connect to myDevices Cayenne you need:

 
  • your WiFi SSID
  • your "WiFi password
  • the Cayenne credentials:
    • client name
    • user name
    • password
Changed:
<
<		After that you import cayenne and create a Cayenne class. This will set up your Wifi connection. After that you call cayenne.myttConnect() to connect to the myDevices MQTT broker. Once the connection is established you can call cayenne.publish(channel,dataString) to send your measurement data. The source code for the Cayenne class and an example showing how this is used with a DS18B20 temperature sensor is attached to this page.
>
>		The CayenneMQTTClient class has a begin method taking Cayenne username, password and client id as parameters. The ssid and wifiPassword have default values but can be specified as well. The begin method will first connect to WiFi and then connect to the MQTT broker at mqtt.mydevices.com. It then subscribes to the command topic such that cmd messages from Cayenne can be passed on to a callback routine registered by the user of the CayenneMQTTClient class. In case of a cmd message the required response message is sent automatically.

If the OLED display is connected the state of network connection will be shown.

The CayenneMQTTClient provides the following methods to publish measurement results:

For temperature:

  • celsiusWrite(channel,value)
  • fahrenheitWrite(channel,value)
  • kelvinWrite(channel,value)
For other measurements, I think that from the name of the method it is clear which type of measurement is treated:
  • humidityWrite(channel,vakue)
  • luxWrite(channel,value)
  • pascalWrite(channel,value)
  • hectoPascalWrite(channel,value)
  • voltageWrite(channel,value), the value must be given in mV
  • digitalWrite(channel,value), value must be 0 or 1

Parsing of command messages

 
Changed:
<
<		https://iotworkshop.africa/pub/AFNOG/Cayenne/cayennePublic.py.txt
>
>		The callback function gets a message, a tuple consisting of the topic and the payload, as parameter. This message must be parsed to extract the channel number and the value. The CayenneMessage class helps with this. Create a CayenneMessage object cayenneMsg with topic and payload (message[0] and message[1]) as parameters.
 
Changed:
<
<		Please rename this file to cayenne.py after download
>
>		cayenneMsg.channel will then contain the channel number on which the command must be executed, cayenneMsg.value contains the value.
 
Changed:
<
<		https://iotworkshop.africa/pub/AFNOG/Cayenne/cayenneDS18B20.py.txt
>
>		You can also get hold of
  • cayenneMsg.client_id
  • cayenneMsg.msg_id
should these be needed.
 
Changed:
<
<		Please rename this file to cayenneDS18B20.py after download
>
>		The code of the CayenneMQTTClient class can be found here:
 
Changed:
<
<		-- Uli Raich - 2019-03-28
>
>		https://github.com/uraich/MicropythonCayenneMQTTClient/tree/master/cayenne
 

Comments

Revision 12019-03-28 - UliRaich

Line: 1 to 1
Added:
>
>
META TOPICPARENT name="AFNOGWorkshop2019"

Connecting to Cayenne

A Micropython class connecting to WiFi and subscribing to the myDevices MQTT broker

Since every sensor node needs to first connect to WiFi and later subscribe to the MQTT broker at mqtt.mydevices.com I wrote a small micro Python class accomplishing these tasks. You will have to modify the code inserting:

  • your WiFi SSID
  • your "WiFi password
  • the Cayenne credentials:
    • client name
    • user name
    • password
After that you import cayenne and create a Cayenne class. This will set up your Wifi connection. After that you call cayenne.myttConnect() to connect to the myDevices MQTT broker. Once the connection is established you can call cayenne.publish(channel,dataString) to send your measurement data. The source code for the Cayenne class and an example showing how this is used with a DS18B20 temperature sensor is attached to this page.

https://iotworkshop.africa/pub/AFNOG/Cayenne/cayennePublic.py.txt

Please rename this file to cayenne.py after download

https://iotworkshop.africa/pub/AFNOG/Cayenne/cayenneDS18B20.py.txt

Please rename this file to cayenneDS18B20.py after download

-- Uli Raich - 2019-03-28

Comments 

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META FILEATTACHMENT attachment="cayenneDS18B20.py.txt" attr="" comment="" date="1553776961" name="cayenneDS18B20.py.txt" path="cayenneDS18B20.py.txt" size="980" user="UliRaich" version="1"
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