Pi Touchscreen Dim with Chromium kiosk -- how can I switch on/off/dim through REACT or NODE.JS commands?

Question

Auto switching touchscreen on/off is critical for our project with 9 RPi's in large home with 6 bedrooms, living, study, play room, etc. The app is React on Chromium kiosk mode, running Node.js handling temp/humidity sensors, motion sensor, window-open (3 to 8 windows/doors per room) -- to be used in tropical weather. A/C heat pump runs with hot/cold water, and in each room a separate fan coil supplies cold or hot air, using RPi touchscreen as thermostat on/off control (far more sophisticated than Nest).

Just started testing "pi-touchscreen-dimmer", which dims light when touchscreen is left for n-seconds...

My question: is there a way to control the dimmer level from either a local Node (firing socket messages), or from Chromium (React) sending commands to a dimmer tool ?

For example, if someone opens a window/door, the RPi gets a "window-open" signal, for which I want to brighten screen to 255x, then display a warning to inform guests that fan coil's cold water supply will be cut off (no chilling, fan only), maybe in 30 or 60 seconds...

P.S. I'll post the whole project on GitHub soon... making good progress !

Answer 1

If you have a look at this question you will see that brightness can by controlled with a simple echo command assuming you have the official Raspberry Pi screen. If not please document what screen you are using.

It basically sends data to /sys/class/backlight/rpi_backlight/brightness with a value between 0 and 255

This saves a lot of inter-program communication by just either writing to this as a file or using a command shell to run the echo command.