omrihar / yeelight-wacom-home

A small side project to control my Yeelight lightbulb from my Wacom Intuos tablet on the raspberry pi

Control Yeelight with Wacom Tablet

This is a small home project I am working on to control my Yeelight light bulb using a Wacom tablet. The basic idea is to use click and drag events on the tablet (Wacom Intuos Draw) to switch the light on and off, to change brightness, color temperature and color. In addition, by starting the light-bulb in different quadrants of the tablet (or with different clicks), I want to enable the bulb in different modes (e.g. color mode, reading mode, change with the day mode, etc...).

The Setup

1. Yeelight lightbulb, with LAN mode enabled.

2. Raspberry Pi connected to the tablet in headless mode (running disconnected from a screen).

3. PyQt5 - A QT application that runs in full-screen and continuously reads the click and move events from the tablet.

4. python-yeelight - A python library to control the light bulb.

Control of the light bulb

There is a very nice and simple library for python (python-yeelight) that enables the discovery and control of light bulbs. Currently it discovers all light bulbs and, by default, enables the first one (I only have one atm).

Connection to the Wacom Tablet

I'm using PyQt5 in order to receive events from the Wacom Tablet. QT5 has an QTabletEvent class that allows to specifically track tablet events. I create a window that covers the entire screen (following this post) and thus is able to get events from the entire tablet surface area. Since I intend to run this on a headless raspberry pi, this should not be a problem.

Challenges / Problems / Limitations

1. The light bulb has a limited rate in which it can receive events. There is a music mode which, however, doesn't seem to work. This means that after using the pen to adjust brightness, the library starts yielding exceptions and the connection to the bulb seems interrupted.

Ideas

• By pressing the button on the pen, the tablet's surface would be transformed to a 2D representation of the HSV color-space. Thus pressing anywhere on the tablet will determine the color (as opposed to dragging to determine the color, as I previously planned).

TODO

• Debug rate limit on bulb - either find a workaround or create a smart way to rate-limit the requests to the light bulb without reducing its haptic response abilities.

• Design the different modes in which the light bulb will be changed. The Tablet supports detecting movement in 2D, as well as pressure of the pen and the pen (and tablet) has buttons to press while dragging.

• Manage to run everything on the raspberry pi (python-yeelight, QT5, the Wacom tablet itself).

• Setup the program to automatically run on startup of the pi, as well as recover from crashes without intervention.