If you were alive in the late 90s, you probably remember this iconic commercial for the Jetta:
My goal for this next project is to make that happen in real life. Well…just the windshield wiper part.
After a whole slew of hurried projects, I decided to take a step back and make something a little more complicated that I can blog as I design.
Concept
So the goal here is to replace the typical power source of my windshield wiper motor with something with more fine control of wiper speed. There will be two circuits involved here: One will stay under the hood of the car and deal with all of the actual motor control while the other will sit inside the passenger compartment and offer controls to the driver. These two will be connected over RS422 for communication.
The user will be able to set the desired windshield wiper tempo and it will try its best to match. I might also throw in some audio processing to attempt to automatically detect song tempo though this might be difficult to do with the limited capabilities of the AVR.
User interface
As far as user interface goes, I’m imagining a little box situated somewhere on the dashboard that includes the following features:
- 360 potentiometer for fine adjustment of wiper speed
- LED bar graph for displaying current speed
- Tap-tempo button for setting tempo
- Tap-tempo indicator LED
- Microphone with some filtering similar to the light up jacket for realtime beat tracking
- Audio gain control
- VU meter bar graph.
- USB connection (through FTDI chip) for realtime interrogation/control
- Power switch to toggle back to normal wiper control function
My idea is to pretty much pull out all the stops with this thing. Some of these features I might not even end up using, but there will be a lot of unknowns in this project, so I want to be ready for that. For example: I’ve never attempted any kind of complex audio processing like beat tracking, but I figured I’d throw in the mic while I’m at it in case I want to try to make that work.
Because I’ll have to do most of my firmware development inside my car (as opposed to comfortably on my desk), I added the FTDI chip to help in debugging.
I really want this thing to look good and operate well, so I will be taking some extra measures to boost the user-friendliness of the UI.
Motor driver
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