IKEA’s products are known for their clean, Scandinavian design and low cost, but it is their DIY or “assemble it yourself” feature that probably makes them so popular with hackers. We seem to receive tips about IKEA hacks with a consistent regularity. [Robin Reiter] has a Bekant Sit/Stand motorized table with buttons to raise and lower the surface, but it doesn’t have any memory presets. That’s a shame because it requires a lot of fiddling with the up/down buttons to get it right every time. It would be nice to press a button, go grab a Coffee, and come back to find it adjusted at the desired height. With a little bit of hacking, he was able to not only add memory preset buttons, but also a USB interface for future computer control.
The existing hardware consists of a PIC16LF1938 micro-controller with two buttons for movement control and a LIN bus protocol which communicates with the automotive grade motors with integrated encoders that report position values. After a bit of sniffing around with his oscilloscope and analyzer, he was able to figure out the control codes for the motor movements. For some strange reason, however, the LIN signals were inverted, so he had to introduce a transistor signal inverter between the PIC master and the Arduino Nano that would act as a slave LIN node. Software was made much easier thanks to an Arduino library developed by [Zapta] for the LIN Bus signal Injector, The controls now have four buttons — two to replicate the original up/down movements, and the other two to act as memory presets.
The code, schematic and a simple wiring layout are posted on Github, in case there are others out there who’d like to replicate this hack. Check out the video after the break where he gives a walk through the code.