Car stereo interface

Matt MC

Let me first say I have an AS degree in Electronics that I have never used. I also have some programming experience. I don’t mind spending the time learning and doing the programming for this project but I would definitely need help on the electronics portions.

What I want to do is be able to use the propeller to take input and send output to and from my Sony deck unit through the CD changer controller, information on the hardware and commands can be found here gnunilink.sourceforge.net/. By doing this I can use the buttons on the deck unit to control stuff and display text on the deck unit, but first the display.

I would like a small color display, like this store.earthlcd.com/s.nl/it.A/id.893/.f?sc=7&category=6. What would be an easy & cheap LCD between 2.5 and 5 inches I could use? Or other option is to only use the Sony deck unit for display, but not as much fun.

Applications: 1. Take input from the oxygen sensor (.2v to .8v typical range) to display an air/fuel mixture ratio. 2. Take input and display from any number of analog sensors. 3. Saving this for last, control a module for playing mp3s. I don’t expect the propeller to play mp3s, but control a separate module such as the ump3 here info.hobbyengineering.com/specs/ROGUE-UMP3-110-A1-100-1.pdf. The problem with this is how would I display the track information? Controlling the ump3 module doesn’t appear to be a problem though.

I could just buy an ipod and the sony controller that hooks it upto the CD changer, but I would like a nice clean design with just a small screen controlled through the buttons on the deck instead of an ugly ipod latched some how to my otherwise beautiful dashboard. Besides, once created you could integrate a number of other applications, such as a garage door opener, activate a NOS system, monitor engine sensors, and more.

I don’t mind spending the dough on this project, but before I spend my time I would just like a consensus on the feasibility and any recommendations on a course of action.

Thanks,
Matt

Mike Green

The EarthLCD display looks like a lot of work. There are two additional voltages (3.0 and 3.8) and you're going to have to do all the programming (in assembly) because of the data rates involved. Why not use Parallax's 2.5" video monitor? The software already exists to do text and/or graphics and it only needs 4 I/O pins instead of maybe 16.

There's existing software in the object library for at least one multi-channel external A/D converter and the Propeller itself can do A/D conversion with a few extra passive components at 2 pins per A/D channel. The Rogue Robotics unit seems to work fairly well although I've had problems using it with a Prop-1 controller ... It seems to drop serial bits sometimes over a period of many hours and the Prop-1 (BS1) doesn't have enough memory for a proper recovery routine. The Propeller should do fine. The MP3 unit does allow you to read and write data on the SD card as well as play MP3 files. You'd have to write your own routines to scan the MP3 files for the meta-tags with the track titles.

Kevin Wood

You can probably do all of this, but you might want to break it up into small chunks.

For video display only, you can use the Parallax video monitor. If you want to build something interactive, check out this post:

http://forums.parallax.com/showthread.php?p=602770

Graham Stabler

And if the 2.5" parallax monitor isn't big enough you can get some nice 5" LCD TV's that work well. There are also video monitors in a range of sizes on ebay.

Graham

Michael Chadwick

The sony display is available here, with no controller, but $19.95 vs $59.95 for the raw display at earthlcd

http://www.goldmine-elec-products.com/prodinfo.asp?number=G13752

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MRC

El Paisa

This not entirely true.
earthlcd.com offers a 2.7 inches graphics lcd (ezLCD-001) which can be program with just about any mcu.
Very easy to program.

Take a look the enclosed file.