From: Neil Weinstock (nsw [at] luna.lc.att [dot] com)
Subject: Proposal: Universal Infrared Remote for in-car use
Newsgroups: rec.audio.car
Date: 1995/07/22

This is something I've been idly pondering for a while; thought it was time to get some feedback.

MOTIVATION
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Nowadays, loads of head units and CD changers come with infrared remote capability. I don't know about you, but I don't find it easy to come up with a place to put a lot of the remotes that come with them, and I don't want to hand-hold the remote while I'm driving. Mounting remotes in the center of the steering wheel, has has been done on occasion, doesn't work when you've got an airbag.

Let's face it, the ideal controls are those you can operate without taking you're hands off the steering wheel. I have these on my '90 Legend to control volume and select from among radio presets. Though minimal, they are incredibly wonderful. Of course, if I ever wanted to replace the factory head unit, I'd have a "fun" time trying to get those controls to work with an aftermarket unit.

SOLUTION
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So, the solution seems to me to be a universal infrared remote for the car. This would consist of three components:

1) The control unit, which interprets the control inputs and generates the infrared pulses. This would be very small and could be hidden anywhere.

2) The input controls, which could either be pre-existing or custom made. These are wired to the control unit.

3) The transmitter LED, which could be mounted somewhere to ensure it has a line-of-sight to the head unit receiver. This is also wired to the control unit.

The advantage is obvious: you can control any head unit (as long as it has infrared remote capability) with controls optimized for convenience in the target vehicle, and integrated into the car. They could be as simple or elaborate as desired.

Or, it might be possible (still need to investigate this more) to adapt the existing wired remotes (like the Sony wand, which I think is pretty neat) to any head unit.

The hardware to implement all this is very simple and very cheap (like maybe $20-$30).

BRIEF TECH DETAILS
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The control unit would be based on some low-end microcontroller. It (the unit, not the microcontroller :-) would have a built-in infrared receiver for the learning function, and some number of inputs for external controls. It would also support the resistor-network controls that seem to be common in cars; I need to investigate this some more, but I think the controls in my Legend are like this, and I wouldn't be surprised if the wired remotes are as well.

A UART would be provided in the control unit, so its behavior could be programmed over a serial PC port via a simple terminal emulator. This is the easiest way to provide an intelligible interface without adding significant complexity and cost to the control unit.

CONCLUSION
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So that's it. Pretty simple concept really, and a pretty simple hardware project. The software would be a bit more work, but something functional could probably be hacked up fairly quickly. When all is said and done, the remote would allow people to implement fairly fancy control schemes without paying a fortune to a installer or doing open-heart surgery to a head unit. Building the controls would be most of the work, but switches and buttons aren't too big a deal if the electronics have been taken care of.

Comments?

- Neil

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Neil Weinstock @ AT&T Bell Labs // What was sliced bread
nsw [at] garage.att [dot] com \X/ the greatest thing since?