Month: April 2019

The Pi running OpenHab is directly below the hot water tank, so rather than adding another wireless node in the airing cupboard, I can run some wired sensors.

Simplest for this purpose is a bunch of DS18B20 sensors, these use a 1-wire protocol which is capable of going the 3-4metre distance. Also only need a three wire cable to connect all the sensors. Used an old mini-circuits box to connect the three sensor cables together with 5kohm resistor pull up in the airing cupboard.

Follow instructions @ https://community.openhab.org/t/gpio-1-wire-temp-sensors-on-raspberry-pi-with-openhabian/20941

On the Pi added the following to /boot/config.txt

# PS - Enable 1-wire sensors
dtoverlay=w1-gpio,gpiopin=4

Use the onewiregpio binding in openhab to retrieve the temperature info, add the three sensors with manually created 1wire.thing:

Thing onewiregpio:sensor:Water_Temperature_1 "Water Temperature 1" [gpio_bus_file="/sys/bus/w1/devices/28-01143f865eaa/w1_slave",refresh_time=10]
Thing onewiregpio:sensor:Water_Temperature_2 "Water Temperature 2" [gpio_bus_file="/sys/bus/w1/devices/28-01143f8d57aa/w1_slave",refresh_time=10]
Thing onewiregpio:sensor:Water_Temperature_3 "Water Temperature 3" [gpio_bus_file="/sys/bus/w1/devices/28-01143d7bdcaa/w1_slave",refresh_time=10]

1wire.items

Number:Temperature Water_Temperature_1      "Temperature: [%.2f %unit%]" <temperature>  { channel="onewiregpio:sensor:Water_Temperature_1:temperature" }
Number:Temperature Water_Temperature_2      "Temperature: [%.2f %unit%]" <temperature>  { channel="onewiregpio:sensor:Water_Temperature_2:temperature" }
Number:Temperature Water_Temperature_3      "Temperature: [%.2f %unit%]" <temperature>  { channel="onewiregpio:sensor:Water_Temperature_3:temperature" }

First pass, using NodeMCU and sensor, powered via USB charger. Since a lot of the wireless technology is based on the ESP SOC this would be a good development platform to experiment with, so worth getting one to play with.

Start with a NodeMCU, a simple Temperature Sensor and one of the many USB power bricks lying around the house.

Solder (badly) the BME280 to a four core cable with a couple of two pin header connectors (GND, 3.3V) & (SCL, SDA) on the end. Connect to the pins on the NodeMCU (GND, 3.3V) & (D4, D5).

Install ESPEasy and configure it to have one BME280 device, connected using MQTT ultimately to OpenHAB. In the meantime tested connectivity by installing Mosquitto on my server. Named the ESP in the living room: “Lounge” and the BME280 sensor “Sensor”:

mosquitto_sub -v -t "/Lounge/Sensor/#"
/Lounge/Sensor/status/LWT Connected
/Lounge/Sensor/Temperature 16.24
/Lounge/Sensor/Humidity 54.18
/Lounge/Sensor/Pressure 1021.65

Too easy, but pretty ugly, with a USB charger hanging out of the wall socket.

Build two more using D1 mini boards, soldering the wires direct to the through hole vias. Deploy one as ‘BigShed’ and the other as ‘TopRoom’.

TODO:

Mixed fleet of sensors:

BME280 Based to get Humidity:

• Utility Room – Attached directly to Pi/Uno
• Main Bathroom – Attached to NodeMCU
• Ensuite – Attached to same NodeMCU as Bathroom
• Kitchen?
• Shed to get outside humidity & pressure

DS18B20 Based to just get Temperature, all attached to same NodeMCU (possibly split Bedroom 4 & Loft off to a separate Node):

• Bedroom 1
• Bedroom 2
• Bedroom 3
• Bedroom 4
• Bedroom 5
• Loft Room
• Landing

Water Tank is monitored by a group of DS18B20 encapsulated sensors, attached directly to the Pi.

Downstairs experiment with ZigBee, this distribution would normally provide a good adhoc network, but not sure the sensors support this. So probably need a ZigBee router:

• Lounge
• Study
• Hall

To Support this deployment need to get:

• 3 ZigBee Sensors
• 1 Zigbee Router
• 4 NodeMCUs (already got)
• 3 (SPI) BME280 Sensors (already got)
• 2 (I2C) BME280 Sensors
• 10 DS18B20 Sensors (already got 3 for water tank)