Having bought the parts for $ 30 and with a good amount of patience, it is possible to build a MP3 player, open source, and ample opportunities for modification. It can be modified so that will accept commands over a serial interface, can be part of an art project, used as a voice for your next smart talking robot friend, or filled with music, and used as is. Insert the card you want any size, up to the theoretical maximum size MMC. All code and diagrams shown here, are distributed free.
Printed circuit board and source code
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Main features of the player: playback in random order, basic navigation in the tracks, volume control, support for FAT32, support for fragmented files, unlimited number of files in the root and high-quality playback. Files with a bitrate of 256 kbit / s are played without interruption. Supports files with different bit rate, maximum - 320 kbit / sec.
Wav -files are also supported, but they must be lesser quality than CD , as long as you do not put a crystal oscillator for PIC controller with greater frequency. In my test device is working, but use the PIC controller clocked at more than 8 MHz at a supply voltage of 3.3 volts is problematic. I'm still working on playback wav -files on this if you are having fun results, reproducing the wav -files, let me know.
To write data to a memory card, you need a reader / writer. In many computers, such devices are built. External USB models are available for sale at a price of about $ 10. Check the format of the file card system, it should be FAT32 instead of FAT16.
For normal playback, download MP -3 files to the card (make sure that all files have the extension ". MP 3 ") and insert it into the player. Turn on the player and it immediately begins playing the first track. Files are played in the order in which they were recorded on a memory card.
To switch to shuffle, hold down the "next track» (next track) when you turn on the player. He will remain in this mode until the next cycle off / on. Once all the songs will be played, the player goes to sleep until the next cycle off / on.
Caution for beginners! This project is an intermediate level. You'll need things like the PIC programmer, some knowledge of programming in C, as well as quite good but not great knowledge of electronics. The oscilloscope also does not hurt. Be careful, the details are very small.
If you're new, check out these books and web sites:
compiler that I used in the project - a compiler for the average bit controllers (midrange compiler)).
All three books Forrest Mims (Forrest Mims) are available in the radio room (Shop radioshak . com ).
Practical Electronics for Inventors, by Paul Scherz and journal Cheknuty and Volta (in the book of the fortress (online shop) they have almost always.)
Why is the project named Sakura? This project began when in bloom everywhere cherries. Sakura means cherry blossom in Japanese. And the first prototype of the project was housed in a pink plastic.
The scheme :
