In FHEM and OpenHab the sensors are integrated using the busware.de CUL USB-stick using the custom firmware CULFW (see step 1 for flashing the stick, I am using v1.44). After this, receiving data is as easy as listening to a serial stream from /dev/ttyACM0. This can be easily tested on your Mac or Linux computer, and is described in the CULFW Reference under "quicktest".
One data package comes in the form: "KaaTTHTHH", where
- K is the code for S300TH,
- aa is the device number
- T is temperature,
- and H is humidity.
H =
line.charAt( 7 ) + line.charAt( 8 ) + "." + line.charAt( 5 );
T =
line.charAt( 6 ) + line.charAt( 3 ) + "." + line.charAt( 4 );
Two example packages and its decoding:
K1122623436 => Sensor 1: T22.2 H34.6
K41106245E7 => Sensor 2: T21.0 H45.6
Now we have everything we need to integrate with home assistant.
We are going to use the HA serial sensor platform to listen to /dev/ttyACM0.Add the following to your configuration.yaml to receveive the temperature values for sensor 0:
sensor:
- platform: serial
serial_port: /dev/ttyACM0
- platform: template
sensors:
temperature_sensor0:
friendly_name: Temperature Room 0
unit_of_measurement: "°C"
value_template: >
{% if states('sensor.serial_sensor')[1] == '0' %}
{{ (states('sensor.serial_sensor')[6] ~ states('sensor.serial_sensor')[3] ~ states('sensor.serial_sensor')[4]) | float / 10 }}
{% else %}
{{ states('sensor.temperature_sensor0') }}
{% endif %}
Note, the decoding of the "6-4-3" pattern using templates. Also we have to decode the sensor device number and ignore all other sensors that are not "0". In this case we will just report the current value (line before endif). This is not a nice solution, sine it will create additional data points in the data base, but I haven't found a better solution yet.
To decode the other sensors, simply add a temperature_sensor1, etc. and change '0' to '1' and also return 'temperature_sensor1'. Add sensor entries for humiditiy accordingly.
After adding this code, you will notice, that nothing will happen. The reason is, that you first have to tell the CUL to report incoming packets. Unfortunately, the Home Assistant serial platform does not support sending, only receiving. Instead we will use a simple 'echo' shell command. Add the following to configuration.yaml:
shell_command:
start_cul: "echo -e 'X21\x0a' > /dev/ttyACM0"
start_cul: "echo -e 'X21\x0a' > /dev/ttyACM0"
Now call this command from an automation action. Add the following to automation.yaml:
- id: '1586784995017'
alias: Start CUL
description: ''
trigger:
- minutes: /5
platform: time_pattern
condition: []
action:
- data: {}
service: shell_command.start_cul
We could have used an even trigger "homeassistant" and only call the shell_command on start up, but I was not sure about the start up sequence (I guess, serial has to configure the connection parameters first).
This work smoothly for my seven sensors so far and saved me some money for buying newer (and fancier) sensors.
