Bellow is a Step-by-Step Guide to installing your own aux input mod, it assumes knowledge in soldering, micro-controller programming and general disassembly skills.
Note, this is not a definitive guide, more of a list of tips and wiring diagrams.
Step 1
Remove head unit from dash... This can be done by bending two coat hangers with small notches to catch on the retaining clips by placing them in the four holes on the sides of the head unit.
They look like a U rotated by 90 degrees, I'd take pictures of mine but they seem to have gone walk-about.
Step 2
Insert your custom removal tools about an inch into the head unit and gently wiggle the head unit from left to right. This can be a bit tricky but once you get the hang of it but will eventually pull free from the dash, and you'll be able to do it in a flash.
Step 3
Remove face plate using a torx screw driver, the cd stacker and the bottom plate of the head unit. These will require two types of torx bits; don't be tempted to use a flat head screw driver because if the bolts are stubborn/stuck you'll strip the head and you'll need to drill the bolt out (I've had to do this and it's not really fun).
Note: Be very careful when removing the stacker, depending on your model there is either a flat grey ribbon cable or a tiny white ribbon cable. Both are very fragile and do have enough slack so that the stacker can be rested on the side, as seen below. Gently lift the stacker off when you have removed the screws to see where it is.
If your CD player has the red connector there are two retaining clips on the side of the plug that can be gently pushed aside to separate the ribbon cable.
The alternate plug is a small white ribbon cable that can be removed by carefully pushing the two brown lugs in the direction of the ribbon cable.
Step 4
Fire up that soldering iron and lets inhale some tin fumes!
Step 5
By following the pin outs on the attached images you should be able to connect them to your proto-board or dev-board to start controlling the TDA7348 and to intercept commands from the face plate.
My solution uses an Atmega8 and small piece of proto board in a hobby box; your's may be different but the pin outs can be used and code modified to suit a PIC or alternate micro.
LCD, labelled as follows:
1: 5V constant supply
2: Button Data (MOSI to microcontroller)
3: Clock (CLK to microcontroller)
4: Chip Select (pulled low when about to send data, to CS on micro)
SDA and SCL are tied directly to micro-controller, they already have pull up resistors so are not required.
Left, Right and Ground are the audio input to the TDA mux. Note, a capacitor needs to be placed in series as explained in step 6.
I have my wires running from the head unit to an external box just behind the passenger side right kick panel and RCA connectors for an aux in connector. This approach has introduced noise into the i2c comms line when the head unit is in standby, this in itself isn't a problem but sometimes my micro is convinced a device is trying to talk to it and holds the i2c line hostage. This is rectified by turning the head unit off and then on again, where the on button is recognised by the micro and releases control of I2C.
Step 6
Wiring up the sweet aux input!
This step simply requires you to wire the aux in to the TDA7348 as seen in the diagram. Note, the Left and Right channels need to use decoupling caps or the sound won't be optimal and will sound dull. They MUST be electrolytic caps that are polarised, the negative terminal feeds directly to the source device (say an mp3 player) and the positive goes in the direction of the TDA7348 chip. I used 10uF 50V caps, overkill but it's what I had available at the time.
Step 7
Program your micro, validate the flash...
Step 8
Test, make sure that all connections are free from shorts and fire her up!
Step 9
Turn head unit on, "pause" the FM station... enjoy your own music!
I'm still developing the interface and am steering away from iPod but instead using an android phone that can be controlled via the head unit and the control sense included in the four pin audio jack; similar to how the headphones that come with most modern phones control media, volume etc.
stacker.jpg
tda_label.jpg
i2c_label.jpg
lcd_interface_label.jpg
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,They were me test units when I was learning how to get the bluetooth and aux working together properly
I feel like a kid in a candy store! AMAZING work Nemesis.
