Building my own AUX input

[CheeseHelmet]

When I first bought my P5, I got a Pioneer head unit just because the stock HU didn't have an aux input. The thing is, I really like the stock head unit, it looks good and has nice big controls that are easy to use without having to take my eyes off the road.

I was bored a couple days ago and starting trying to figure out how I could make an aux input that would at least allow me to play music through the MD/Tape input (no fancy ipod integration for now). I found this guy's documentation about the bus protocol and I was able to build a decoder to get raw data off the bus.

I'd like to know if anyone has some captures of tape deck's initialization, I know how the CD player does it, I just need to know what codes the tape deck sends back to the HU. If no one has that data, I'd gladly pay for shipping to borrow a tape deck (or I'll buy it off you if you don't want it back).

My intentions are to publish all source code and schematics once I have something working so anyone with a soldering iron and some free time can build their own aux input. For the time being, I'll leave you with the source code for my decoder and a human-readable transcript of the radio's initialization sequence. If you need a schematic for the little circuit I had to build, I'll whip something up

TL;DR: If you have a tape deck that's compatible with an 02 P5 head unit, I'd like to borrow/buy it.

EDIT: I've got a tape deck in the mail, hopefully it'll arrive this week.

 

[CheeseHelmet]

I did a little more work today, specifically on the decoder. It works a lot better now and makes reading data from the head unit super easy. I was even able to fill in the data that I thought was "garbage". I also disconnected the CD player to see what the difference is (spoiler: the bus is pretty quiet ).

Here's the latest:

• The new code for the decoder: http://slexy.org/view/s2FZvRgjMH
• A small python script to be used with the decoder: http://slexy.org/view/s22e0RYFhf
• The updated initialization sequence: http://slexy.org/raw/s2q9DqVnzY

 

[CheeseHelmet]

More progress, I talked to the radio! Here's a transcript where I was able to spoof the CD deck's "powered on" message (the CD deck is unplugged):

1280802498.920487 38C0 4 <-- The radio asks if the CD deck is present
1280802498.920566 B813 0 <-- This is me, I say it is :D
1280802498.920602 0890 4
1280802498.920636 18A0 4
1280802498.920668 68F0 4
1280802498.920701 58E0 4
1280802498.920734 7800 4
1280802498.920767 39B0 4 <-- The radio responds here with a "Wake up" message

I think that's all for tonight

 

[CheeseHelmet]

After doing more analysis of the timing of the pulses I'm now able to send proper messages back to the radio.

Mazda CD players are so vulgar:

Maybe it's pissed off because the CD deck isn't connected

EDIT: I should probably clarify that this means I have a working AUX input, it just happens to replace the CD player (which isn't what we want). Now I have to wait to get my tape player...

 

[Sport23]

Awesome! Subbin.

 

[CheeseHelmet]

I got my tape player yesterday (had to go pick it up in the US, the border guard laughed at me for crossing the border to buy a tape deck ).

Today I documented the tape deck's commands and worked on my decoder. A few minutes ago I was finally able to trick the head unit into thinking the tape deck is plugged in, I just have to clean up the code and add some missing functionality (my code doesn't yet respond to rewind/fast-forward messages).

I also started a wiki page to document the protocol which can be found here: http://nikosapi.org/wiki/index.php/Mazda_Radio

Anyone can edit it, so if you spot a mistake feel free to fix it!

 

[CheeseHelmet]

It works!

I'm actually sitting in my car right now listening to my ipod through the stock head unit!

Really crappy pic of how it's currently set up:

A pic of the little circuit that makes it all happen:

I didn't have any spare connectors for the tape input on the head unit so I had to solder the wires to the HU:

I'm trying to source some connectors atm but it doesn't look too promising... I'll get the source code and schematics out asap.

 

[CheeseHelmet]

What's taking me so long?

iPod integration FTW

It actually works quite well, if only I had some good iPod dock connectors it would be awesome. Source code coming soon, I promise!

 

[CheeseHelmet]

Documentation!

http://www.mazdas247.com/forum/showthread.php?t=123782584

Please post any questions in ^ that thread.

 

[ghettoracingkid]

for like $80... gromaudio makes one that plugs right into the cd charger port and charges the ipod and works the same way.

good job man... props to you. (serious)

 

[CheeseHelmet]

for like $80... gromaudio makes one that plugs right into the cd charger port and charges the ipod and works the same way.

Where's the fun in that?

I probably spent $50 to make my own, but that's only because I had to buy a tape deck. Now if I had to buy all the parts and make one it would cost about $20.

 

[ghettoracingkid]

there is no fun.

If i knew how i would have done the same thing.

Its the same reason why I would rather build an engine then buy it...

its more fun and rewarding then opening a box and plugging it in.

 

[chuyler1]

Nice work man! If I still had my P5 I'd try this out just for the hell of it.

 

[dishe]

isn't there a mod that just requires some wiring to the plug, no controller board, etc... or is that for newer head units?

I have a 2007 MAzda 5, and was about to buy a GROM aux input when I found someone mention that I could do it for about $5 worth of parts. I'm searching for more detailed info on this, and found this instead. Are we dealing with a totally different unit?

 

[CheeseHelmet]

isn't there a mod that just requires some wiring to the plug, no controller board, etc... or is that for newer head units?

I have a 2007 MAzda 5, and was about to buy a GROM aux input when I found someone mention that I could do it for about $5 worth of parts. I'm searching for more detailed info on this, and found this instead. Are we dealing with a totally different unit?

Yea, this probably isn't what you're looking for. I recall seeing a howto (I think is was on some RX-8 forum) showing how you can get an audio input by adding a couple jumper wires to the rear aux connector. Can't find it atm but I think what you're describing is possible on newer head units.