Hi All,
I got a IKEA BEKANT motorised desk. I was trying to hack the controller, so i could send my own signal (via USB) for moving up and down. Basically controlling it via my computer. It
seemed pretty simple, just 3 wires. But, you guess, its not.
The remote control looks straight forward, 2 momentary push buttons, one moves it up, the other down. Added a photo of the PCB.
Th power supply is: DC 34V 200 watts (ROL ERGO). It delivers 24V DC.
The basic setup is like this:
LEFT +----- (3 wires) Remote Power (DC 24V) ----+ RIGHT
LEG +-------------------- 3 wires ----------------+ LEG
After opening the remote control, i found a PIC16LF1938 inside and that explained partly why its not that simple. There are 3 wires: Red, Blue and White. I measured the following DC voltages (without any buttons pressed):
Red - White = 24.62V (equals power supply output)
Red - Blue ~ 14-15V (fluctuates)
White - Blue ~ 9-10V (fluctuates)
To me to seems a bit of overkill to use a PIC16 for this pretty straight forward function?
The manual states the motors stop automatically when it reaches either end. Not sure if thats why they need a PIC16, maybe to measure some sort of overload? It also states you need to wait 9 minutes after operating the motors for 1 minute (cool down).
Last thing, the circuit doesn't seem to be fully populated, so i'm guessing its some type of standard design. I was trying to google some numbers, but i got nothing.
These are the numbers on the other side of the PCB
- CTI150
- E157925
- 14 19 94V-0
- 68002420
- BAB 2012-03-24
So, my question is, is there anybody that understand how (and why) it works? Somehow the motors need to get both (simultaneous) the signal to start turning, on top it needs to understand which side to turn (polarity?). I'm not thinking its just 'shirting to wires' like a simple switch. I couldn't open the legs, but im guessing there are a few components there as-well. I was also looking at h-bridges, but im not getting the idea that thats on the side of the remote. Maybe its inside the legs?
Im really interested to learn how this actually works!
The goal is to make something so i can send/create the signals myself (even without the remote).
I saw one guys did this by opening the front-panel and shorten the push-buttons, but thats to simple! ;-)Many thanks!