MP3 Player Update

By | June 28, 2006

MP3 Player Schematic

I decided to give a bit more details on my MP3 player today. Above is my original schematic that I designed back in January (I’ve really been lagging a bit on this project). The design remains basically the same today, with a few minor changes.

For instance, in the schematic I have the LCD backlight controlled through a transfer gate, but after looking at the PIC’s datasheet and measuring the current drawn by the backlight, I decided that I would be able to connect the LCD directly to the PIC. As an added bonus, I connected the LCD to one of the pulse width modulated pins on the PIC and now have fine control over the brightness of the backlight. This will allow me to fade the backlight on/off when the user hasn’t pressed any buttons in a certain time period (power saving feature, yay!).

On another front, the SD card still gives me problems, and I have sampled some 3.3V LM2936 voltage regulators from National Semiconductors1. I’m hoping that when the regulators arrive I will have more success with the SD card; imprecise voltages can have a large effect on the SD card operation from what I have read online. Up until now I have been powering my SD card through a simple voltage divider.

1.  A quick tip for those of you who want to order samples from National Semiconductor: make sure you don’t use your email alias. Due to the high number of samples requested from email addresses, they want to charge you; instead use a low-brow email address like a university account and you should sail through without paying a dime.

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