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Our first DAC chip never produced any output for unknown reasons and was replaced. Then the MP3 chip stopped producing LRCLK and was replaced. Luckily we had started work on this final project before even finishing the other labs for this course so in the final week of the semester things came together and started working. We had been developing the CD-ROM and the MP3 side of things on separate STK boards and in the last couple days before presenting we combined boards to use one STK-300 board. After a substantial amount of debugging and tweaking we produced a project that met all our initial goals. It played MP3 files from various CDs cleanly and smoothly. It displays the correct track titles and scrolls them back and forth if they do not fit entirely on the LCD. It displays track number and time on the LCD. It allows previous and next track seeking. It allows digital volume control. It plays MP3's up to 192kbps. It amplifies the stereo output enough to drive speakers.
If we'd had more time, we could have...
- Found a laptop CD-ROM drive and a laptop ATA plug adapter. Laptop drives use less power and run off of five volt supplies
- Added more buttons to control pausing and stopping
- Worked out the last few bugs in the software
- Reworked the MP3 serial bus transmission assembly code to squeeze out a couple more clock cycles of efficiency, which might boost the sampling rate up beyond 192kbps
- Had a circuit board fabricated and soldered up to decrease overall size
- Added user control of the digital bass and treble controls within the STA013