Rabbit MP3 Player

Rabbit MP3 Player (PCB)

These pages follow on from my breadboard MP3 player, you should take a look at those first if you haven't already.

Here are a couple of photos of the boards. You will see that I had solder resist on these. The reason for this was that I have a number of tracks very close (running between surface mount pads) to pads and I thought that soldering to them might be quite difficult.

If you look at the bottom of the board, to the lower left you will see where I've had to cut through a track. The first thing I did when getting the board back was to check the power supplies for shorts, and I found that the +3.3V line was shorted to Ground. For some reason, the autorouter had decided to route a track on the bottom of the board through the pad of a through hole component. This picture (taken from the Eagle board layout) shows the 3.3V track highlighted in blue passing through the edge of a pad.

I should have checked it better. Still, it's a simple error to fix.

I started assembly by putting on the power connector, the two LEDs, and resistors R16 and R17. I then applied power to the board - and both LEDs came on - wahoo!

Next, I soldered on the two surface mount chips. I did this early because it would be much harder getting to the legs if the board is populated with other components. I found the best way to cope with a surface mount IC is to position it first, then put a tiny blob of solder on the iron, holding the IC in place with one hand, tack on leg down. Once this is done it should be possible to solder down the other legs properly. I think I need a bit more practice, but it seems to have worked okay. I did spot one minor issue with the footprint for the D/A chip. It is exactly the same size as the chip. Now, I'm sure that a flow solder machine will be fine with this, for hand soldering a bit more room would be nice.

Having got both chips on, I then did the resistors, capacitors and then connectors.

This picture shows the board as it is now, with the Rabbit module connected to the rear.

While I was waiting for the remaining components to turn up, I decided to check to see if the oscillator runs okay. The picture below would suggest that its just fine.

Once the final components arrived, I powered on connected to the Internet and it worked!

What's Next

I have found some problems. Mainly due to the speed of the Rabbit processor. I found that it was taking too long to parse the stream information. I also found that if I use my Internet connection for anything else, I run out of data. The first of these issues can be solved (I think) by re-writing the parse routine, and making it specific rather than generic. The second should be sorted by adding in a buffer, so read data of the Internet into a circular buffer in software before playing it out the the mp3 decoder chip.

Other things to do are to fix some component size issues on the PCB, add an on-board regulator for 3.3V and possibly 5V (if there is room). There is still no user control input.

I think that once these minor issues are resolved, it will be time to move onto the next version.

Download Project

You can download the complete project in one zip file (97.5KBytes).

This zip file contains a corrected board layout with the short removed. The foorprint for the D/A has not been updated, and there are a couple of issues with the hole spacing for some of the caps. The software is also included.

Build Your Own

I have two original PCBs, as described above. If you want one of them, please Email me for details.