Plans for the Next MP3 Player


Posted on Feb 6, 2014

This new design has replaced the old one. The design shown on this page is obsolete. The new design has more features, is flash upgradable, is much easier to use, costs less, and is actually available if you`d like to buy one! It`s better than this old design is almost every way. These old pages are still available, mostly for reference. Disclaim


Plans for the Next MP3 Player
Click here to download the full size of the above Circuit.

er: This design data is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. Matthew Burnham reported that hy built the circuits shown in this schematic and got it to work. This diagram was drawn after I built the player, bit it looks like it`s probably correct. It`s a good idea to avoid placing the MAS3507D chip in its socket until the 3 volt power supply has been verified. The decoder chip is expensive and it probably will be damaged if 5 volts is applied. If you are very concerned about sound quality, you may want to add more power supply bypassing to the D/A converter, perhaps with ferrite beads or inductors. The CS4327 chip is supposed to be used with a low-pass filter on its outputs. I didn`t build this on my first board, but I will add it to my next design. The CS4327 data sheet has some good suggestions about what to do for a low-pass filter. The pushbuttons are very simple, and the 8051`s port pins provide the pullup resistors, so all that is necessary is to connect the three buttons. They must be normally open momentary contact types. The firmware contains some code to avoid de-bounce the signals. This last circuit is optional, but if it is not used, whatever signal would normally drive the 8051`s RXD pin must not be connected. When the firmware uses the 8051`s serial port in mode 0, both TXD and RXD...




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