set our requested room temperature through the interface of Home Assistant.
Preparing the host
There is hassbian, hass.io, homme-assistant itself, … as you see, not confusing at all :). I’m using a regular debian based system since at least I know ebusd works in a debian environment. I’m not familiar with docker (hass.io) and its limitations.
A detailed description to setup your host can be found here.
Initial temperature test using Home Assistant
It’s time to get our heater commanded through Home Assistant.
In general it’s good to:
read a few intro’s on Home Assistant before you jump in to it
get Samba up and running so you can edit your home assistant files from your standard working computer (again enough other tutorials can be found)
Concept
We’ll be using python scripts to trigger actions from Home Assistant to ebus(d).
In this way we can focus on making all the ebus related items running in python and we don’t have to deal with the custom Home Assistant syntax. I personally prefer spending time learning python over learning a custom program specific language/syntax.
python scripts
We’ll create a few python scripts to test if we can control our heater from python. On the Pi we will create a new folder python_scripts locate the scripts in /home/homeassistant/.homeassistant/python_scripts.
The script below with the name set_temperature_on.py will set the day and night temperatures to 21C by calling the appropriate ebus commands directly from the command line (making use of the subprocess function). The second part of the script just does an additional check if it was really set correctly.
create the same script with the name set_temperature_off.py where msg2 in the script below has been changed to msg2=15. (Yes, I know this is a stupid way of working and we should give the temperature as an argument to the python script. But for initial testing/debugging this is good enough.)
import subprocess
import time
msg2="21" #setpoint temperature degrees celsius
msg1="ebusctl write -c f37 Hc1DayTemp "
cp = subprocess.run([msg1+msg2],shell=True,stdout=subprocess.PIPE)
msg1="ebusctl write -c f37 Hc1NightTemp "
cp = subprocess.run([msg1+msg2],shell=True,stdout=subprocess.PIPE)
#redundancy check if it is truly set
time.sleep(60)
cp = subprocess.run(["ebusctl read Hc1DayTemp"],shell=True,stdout=subprocess.PIPE)
temp=cp.stdout
if int(float(temp[0:4]))!=int(msg2):
# if not set correct
msg1="ebusctl write -c f37 Hc1DayTemp "
cp = subprocess.run([msg1+msg2],shell=True,stdout=subprocess.PIPE)
cp = subprocess.run(["ebusctl read Hc1NightTemp"],shell=True,stdout=subprocess.PIPE)
temp=cp.stdout
if int(float(temp[0:4]))!=int(msg2):
# if not set correct
msg1="ebusctl write -c f37 Hc1NightTemp "
cp = subprocess.run([msg1+msg2],shell=True,stdout=subprocess.PIPE)
else:
print("setting correct")
check if the scripts are really working by running the command from the raspberry pi terminal python3 -i set_temperature_on.py
as an additional check, on the thermostat you will see the temperature setting change
Python script has set temperature to 21 degrees!
do the same for the script python3 -i set_temperature_off.py
Now this is working, we’ll link it to Home Assistant.
If you’ve followed Home Assistant intro’s, you know all magic happens in the configuration.yaml file(s).
We’ll be using the shell_command component which basically just executes a script in the terminal / command line of the raspberry.
Add the following into configuration.yaml and reload/reboot home assistant.
if you select the set_temp_low and set_temp_high and press “call service” the temperature will be set to 15 and 21 degrees :)
Service becomes available in Home Assistant
Clean up method
In the sections above, we’ve demonstrated the basic functionallity of controlling the temperature requests. Next steps are:
to provide the temperature as an argument from Home Assistant to the python script (instead of the hardcoded values from above)
get rid of seperate python scripts for each function (harder to maintain)
make sure not multiple people write at the same moment to the ebus (don’t want to confuse our system)
Adapt python scripts
Starting with the python scripts:
We want to provide the temperature as argument to our python script (have msg2 as an external input in our script)
We’ll use the getopt module in python and parse the arguments to create a temp setpoint,
import getopt
# check if passed options are valid
try:
options, args = getopt.getopt(sys.argv[1:], 't:',['temperature_setpoint='])
print(options)
print(args)
except getopt.GetoptError:
print("incorrect syntax")
print("usage: python3 set_temperature.py -t <value>")
print("default to 12 degrees")
msg2=12
sys.exit(2)
for opt, value in options:
if opt in ('-t','-T','--temperature_setpoint'):
msg2=value
print("successful argument")
print(msg2)
running the script in commandline becomes: python3 /home/homeassistant/.homeassistant/python_scripts/set_temperature.py -t 20.5
User interface
In configuration.yaml, we’ll define three input boxes for setting a temperature (night, day and an additional one for instant change of the heating).
The critical part are the additional {{}} arguments in the shell_command definition. The exact name of the argument you need to find back in the states menu in the user interface.
