Now that we have the amplifier taken care of, let's get some tunes to the system by letting the XM direct unit communicate with the computer's Com (serial) port.

When XM introduced the XMPCR, it solved all the problems that CarPC users had with regard to controlling XM stations via the CarPC. Unfortunately, XMPCR was quickly discontinued, because a listener with a programming background figured out a way to record the music on the radio to MP3 - along with full tagging information. The RIAA complained, and the product was pulled from shelves within 24 hours.

So how do we now use the computer to control the XM unit? Well, the people over at iHacked.com figured out a way to make the good old XM Direct unit talk to the computer over a serial cable. You'll need to do a little bit of extra work for this, but it's worth it.

Parts you will need:

8-Pin Mini-DIN cable (older Mac printers use them) Female DB9 connecter and hood 4-Pin Molex connector Black and red wire

Tools you will need:

Digital voltmeter Soldering iron Screwdriver

Cable Pinout:

8 Pin Mini-DIN to DB9

Pin 1 - Pin 3 Data Receive
Pin 2 - Pin 2 Data transmit
Pin 3 - Pin 5 Ground
Pin 6 - 12V
Pin 7 - 12V
Pin 8 - Ground

Figure 19: I-hacked.com's XM Commander Cable

Figure 20: I-hacked.com's XM Commander Cable pinouts

Now that we have all that installed, it's time to worry about the front end, and how we'll actually control this CarPC.