At this moment I’m working on making an open source Lego Power Functions receiver, with the same functionality as the ‘normal’ infrared receiver, but with some extra features:
- Servo output
- Xtra small size (standard 2×4 Lego brick)
How did this get started?
Some months ago my nephew asked Lego Power Functions for his birhtday, and it triggered my interest immediately. Motors, batteries, LED lights in combination with LEGO, that sounded like what I had been doing with my brother years ago (he building the lego, me adding lights and sound and locomotion). After searchin a bit on the internet I found that LEGO has ‘opened’ the standard they use for the infrared protocol, and published a nice pdf with protocol info. So far, no one has made an open source receiver. I thought it would be interesting to see if I could squeeze the receiver into a standard brick, and then let others build new and amazing constructions with that brick. Back to my roots: me doing electronics while someone else uses those electronics to build nice LEGO contraptions!
What is the status?
I’ve coded most of the protocol, only the ‘timeout’ feature has to be implemented. I’ve used an Atmel Attiny44A as microcontroller, and a TSOP4136 infrared receiver. I can now succesfully receive the two modern remote controls, still have to test the old fashioned train controller. Servo output is now also working on my prototype. I still have to finish my design, see how well the code behaves and measure some features of the original receiver to better mimic its behaviour in cases that are not -completely- described in the protocol document
What are plans for the future?
I’ve ordered PCB’s for a final / better prototype including motor controller, and I want to test that before making any sources public. When I’m happy with the performance I’ll open source everything: schematic, board file, firmware and my design considerations. Also, I’m planning to do some writeup on the codes used by several transmitters.
Are you looking for help?
Well, maybe someone could help me build a nice LEGO vehicle using (and showcasing) the small form factor. You’d need to house a battery, a 2×4 LEGO brick and any motor / servo to your liking.
Can you show us something?
Stay tuned for more!