Hand tools and fabrication machines
Some time ago I bought a led strip dioder from Ikea, it was funny and not so expensive for a led bars sold by a big store, in Europe is about 20 euros. Though after a while, when I started to make home automation projects I left it in my canteen replaced by a controllable led strip made by a famous maker.
Today, the way to the domotic world has brought myself to several mysensors projects and when I got the dioder back in my hands, suddenly I thought that I could make it controllable from my home automation system.
Thanks to this page I was able to figure out how the dioder is working: basically we have 4 bars each with 8 common anode RGB led. The bars are connected to a connector box where we have also a plug for the power unit (12V) and a plug for the controller unit. This project is focused on the controller unit. This unit has the power button, a wheel to change colors from white (not real white but all RGB on) to red and other two buttons to make colors changing automatically.
This unit is described here but my version is a newer one so I investigated about the new electrical schema: there's a voltage regulator to get 5V but the core is the MC SC91F729BM that get as analog input a level going from 0V (white) to 5V (red) according to the wheel position and 3 digital input coming from the buttons (push button = 0V). The three PWM outputs goes to the 3 MOSFET used to command the led bars, connecting and disconnecting (PWM) the 3 RGB leds cathodes to the ground. Now that we know how the dioder is working we can decide what we want to do. I replaced the SC91F729BM with an Arduino Mysensor node, having also the opportunity to change the first and third button behavior (that I never had used) to make a dimmable LED bar with a UP and DOWN buttons. Since there's already a 5V logic I'm using an Arduino pro mini 5V node sensor, the Radio nRF24LU1+ and than a DC-DC step down voltage regulator to provides 3.3V to the radio module.
The Arduino program is based on dimmer sensor node and this post where Jason Judge explains how to make a RGB colours wheel via Arduino, basically how to convert an analog value to RGB and then to HSV. The standard RGB wheel goes from red to yellow to green to blue to purple and red again, but the IKEA dioder goes from white to yellow to green to blue to purple and to red, so to keep the same behavior I made a change in the algorithm.
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