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update mqtt with sensor readings from ds18b20
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MQTT Temp Sensor

Simple temperature sensor for the ds18b20 that sends it's results to a MQTT broker. It was written for the raspberry pi but it will likely run anywhere.


This assumes a ds18b20 is wired properly to the raspberry pi and a working mqtt broker. Cert authentication with mqtt is currently not supported. I suggest only using this on an internal network for that reason.

Pi DS158B20
vcc 3.3v
gnd gnd
sig GPIO4

4.7K pullup resistor across vcc and sig. This is important to prevent inaccurate readings. If a longer line is needed (+1m) I suggest using a sheilded cable like eth5 or eth6 and reducing the pull up resistor to 2.2K.

Basic usage

./tempMon -mqtt.username=username -mqtt.password=password

Usage of tempMon:
  -bind_interface string
    	Interface the network is bound to (default "wlan0")
    	Debugging using test_data.txt
  -mqtt.clientID string
    	MQTT client ID (default "room_temps") string
    	MQTT Host (default "")
  -mqtt.password string
    	MQTT password (default "pass")
  -mqtt.username string
    	MQTT username (default "user")

If using multiple devices make sure -mqtt.clientID is unique for each one.


  1. Download latest version from or build yourself
  2. Copy to any directory on the pi. (/home/pi/tempMon)
  3. Update /etc/rc.local to start at boot. Add to end of file before exit 0
modprobe w1-gpio
modprobe w1-therm
/home/pi/tempMon -mqtt.username=user -mqtt.password=pass -mqtt.clientID=XXX
  1. Reboot

MQTT Message




  "mac_address" : "11:11:11:11:11:11",
  "ip_address" : "",
  "ts" : 1514684628,
  "celcius" : 24.625,
  "fahrenheit" : 76.325


  1. Verify /sys/bus/w1/devices/w1_bus_master1/w1_master_slaves has has a device listed. Should be something like 28-XXXXXXXXXxXXX
  2. Verify /sys/bus/w1/devices/28-XXXXXXXXXxXX/w1_slave contains text data
79 01 4b 46 7f ff 0c 10 29 : crc=29 YES
79 01 4b 46 7f ff 0c 10 29 t=23562

If any of the above are not working google instructions for getting the ds18b20 working before using this.

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