Set Brightness Command Requiring 2 Runs

[griffinburkhardt]

Hi all, I am writing a basic script to set the brightness of my lights. I will be able to set the brightness level of a specific room without calling the light.turn_on command in Home Assistant. To test this, I have a print statement to indicate that the correct light entity is set to the correct brightness level. I'm not sure why, although I need to execute this code twice for the brightness level to change.

import asyncio
from kasa import SmartDimmer
from datetime import datetime

kitchen_lights = SmartDimmer("192.168.86.64")
bathroom_lights = SmartDimmer("192.168.86.65")


async def kasa_set_brightness(entity, brightness: int):
    await bathroom_lights.update()
    await kitchen_lights.update()
    await entity.set_brightness(int(brightness))
    print('The brightness is now ' + str(kitchen_lights.brightness) + ' at ' + str(datetime.now()))


asyncio.run(kasa_set_brightness(kitchen_lights, 60))

When executed, the output indicates that the brightness level is set to the previous level, 25, set in a previous test:
The brightness is now 25 at 2022-11-02 00:09:47.837739

When executed again, the output indicates that the brightness level is set to the actual level, 60:
The brightness is now 60 at 2022-11-02 00:13:13.598657

[rytilahti]

Are you sure it is not changing the brightness? Regarding to to reported values, you need to perform an update() to obtain the new values after the change as information returned by properties is cached (see https://python-kasa.readthedocs.io/en/latest/smartdevice.html#smartdevice-class and https://python-kasa.readthedocs.io/en/latest/design.html#update-cycle).

[griffinburkhardt]

Hey rytilahti, appreciate the response. So it is indeed changing the brightness, it's just the update() that seems to be off. Could you please help me understand where it should be located in the code? I have added two update() snippets before I call the function and it is still pulling in the old/previous value.

import asyncio
from kasa import SmartDimmer
from datetime import datetime

kitchen_lights = SmartDimmer("192.168.86.64")
bathroom_lights = SmartDimmer("192.168.86.65")


async def kasa_set_brightness(entity, brightness: int):
    await bathroom_lights.update()
    await kitchen_lights.update()
    await entity.set_brightness(int(brightness))
    print('The brightness is now ' + str(kitchen_lights.brightness) + ' at ' + str(datetime.now()))


asyncio.run(bathroom_lights.update())
asyncio.run(kitchen_lights.update())

asyncio.run(kasa_set_brightness(kitchen_lights, 70))

[rytilahti]

So the problem is that you are using asyncio.run() multiple times (which creates a new event loop that won't work) and not calling update after the set_brightness call. Here is how I would do it:

import asyncio
from kasa import SmartDimmer
from datetime import datetime

kitchen_lights = SmartDimmer("192.168.86.64")
bathroom_lights = SmartDimmer("192.168.86.65")

async def kasa_set_brightness(device, brightness: int):
    await device.update()  # you could skip this, if you don't need the actual device state before changing the brightness
    await set_brightness(brightness)
    await device.update()  # fetch the new device state
    print(f"The brightness is now {device.brightness} at {datetime.now()}")


async def change_brightness(devices, brightness: int):
    for dev in devices:
        await kasa_set_brightness(dev, brightness)
    # if the brightness change is wanted simultaneously instead of sequentially
    # await asyncio.gather(*[asyncio.create_task(kasa_set_brightness(dev, brightness)) for dev in devices])


asyncio.run(change_brightness([kitchen_lights, bathroom_lights], 10))  # this launches only a single event loop

[griffinburkhardt]

Ah okay, I think I figured it out. I added another update() after the set_brightness command per your example. Quite a simple tweak after all this testing haha. I don't need the loop at the moment, although I appreciate you adding that in—it should work with no problem. Thank you for your help!

import asyncio
from kasa import SmartDimmer
from datetime import datetime

kitchen_lights = SmartDimmer("192.168.86.64")
bathroom_lights = SmartDimmer("192.168.86.65")


async def kasa_set_brightness(entity, brightness: int):
    await entity.update()
    await entity.set_brightness(int(brightness))
    await entity.update()
    print('The brightness is now ' + str(entity.brightness) + ' at ' + str(datetime.now()))


asyncio.run(kasa_set_brightness(kitchen_lights, 20))

This now sets the brightness of the selected light without having to run twice and without throwing any errors. I'm having trouble getting Home Assistant to run this script as a service, although I'll open another discussion. I don't think I have the .py file setup correctly for Home Assistant to use.