SanDisk User
Posts: 34
Registered: ‎04-30-2010

Re: I want to build a dock for my car

@lylehaze wrote:

I have found the communications method between the dock and the Fuze, and it's not through the USB port.

So far I have programmed a PIC microcontroller to control all the same things that the Sansa dock can do, and 

as soon as I get some free time I'll go looking for additional commands (just for fun).


I'll be making a 12 volt to 5 volt supply next, with switching for the Fuze, so I can detect and respond when

the car gets shut off.  It's one of those "Oops" things..We want to turn the Fuze off AFTER the power is shut down.

But that means my little car-lod will need two power lines. One switched to tell me when the key has been turned off,

and the other to keep my circuit alive just a little longer.. long enough for the Fuze to power down, and THEN I'll send

the "Power" signal. At least I can make sure it's a good quiet power supply.


It's been a lot of fun so far. I wish I had more time to play with it.

I'll probably start a separate thread once I have it a little more complete.



 Wow - good work!  How did you find out the interface details?  Or, is it a trade secret? <G>
 I'm looking forward to your thread describing it!
Posts: 17
Registered: ‎05-19-2010

Re: I want to build a dock for my car

After buying my Fuze, I found this forum while looking for better ways to hook it up in the car.

I saw this thread, and I got curious about how the docks communicated, so I bought one.


I think I had my dock for about an hour before I cracked it open and connected the Oscilloscope. Smiley Happy

Quite honestly, I don't have much use for a dock in my house. But I want the car hookup to be

just right, and I'm willing to work for it.


Anyway.. the first PIC I used didn't have comparators, so that had a problem reading 3 volt signals

into a 5 volt PIC.. I found an older PIC that has 2 comparators on board, and things were looking good.

I wrote the code, and it worked, but not reliably.  After two days of looking for trouble in the code, I

raised the clock speed of the PIC from 8 Mhz to 20.. and suddenly it worked perfect. If it ain't right,

run it faster!


Regarding the "ugly details".. I'm not sure yet how much I'll tell. I think this forum is a really great

resource, and I want to make sure I won't be upsetting our "host" by making the information available.

If any admins want to comment on this, I'd love to hear it!


I was also considering selling a few of these, but it's not lending itself easily to that end. The connector

itself has to be hand-wired. I thought of doing it the way SanDisk did the stock cable, but it turns out that

they used an unusually thin circuit board. Normal FR-4 is too thick to fit between the two rows of pins. 

It's certainly a bit more complicated than just a jumper too..


Maybe for now I'll just build mine, and see what happens after it's running. I'll try to get my next parts

order out this week, and might be soldering things together by the middle of next week.


More details will follow.. as I get time to finish this.