e016040.PDF

ELECTRONICS ONLINE

More MP3 Projects

DIY portables

A few months ago under this heading, we presented a number of Internet

addresses for MP3 projects. Most of them are based on re-using hard-

ware from an old PC. However, there are also other possibilities, includ-

ing projects for building your own portable MP3 player.

computer mouse. An LCD can be

stuck on top of the circuit board, and

the newest version allows the con-

nection of a CD-ROM drive as well

as a hard disk drive. An accompany-

ing PC program enables the user to

download files from the PC to the

hard disk. All circuit board layouts,

software and source code for the pro-

ject are available free of charge. This

project has been created by three

Argentinean electronics engineers.

The estimated cost is around 130

dollars.

The High Capacity MP3 player van

MPRJ [3] is a design that contains

more ICs, but it certainly still

deserves the name ‘portable’. This

player uses a normal (mini) hard disk

drive, which provides enough capac-

ity for hundreds of hours of music.

Thanks to a 24-bit DAC, this unit

delivers outstanding sound quality.

The player can handle various types

of MP3 compression, so the user can

decide what level of sound quality

he or she wants. MPRJ can even pro-

vide all of the components for this

project. You can buy a fully assem-

bled and tested circuit board ($150),

a bare circuit board or the individual

components. The source code for the

ﬁrmware is available for anyone who

wants to make a few changes to

how the player works.

The design of the MoP3-player from

Frank Hickl & Mario Becker [4] is still

under development. This system is

built around an inexpensive

MC68HC11 embedded controller. As

with many other players, MP3

A design based on a PC motherboard, a hard

disk or CD-ROM drive, a few pushbuttons, an

LCD module and some special software is not

such a bad approach to making your own

MP3 player, but the result can hardly be said

to be compact. Nowadays, the subject of MP3

has become so popular that an increasing

number of electronics engineers and hobby-

ists have given their attention to it, with the

result that you can now find complete web-

sites that are dedicated to the construction of

truly portable (as opposed to ‘moveable’)

MP3 players. A (mini) hard disk, CD-ROM

drive or flash memory card is used as the

storage medium.

The MP3Projects site [1] is a good

starting point for searching for such

projects. This site gives an extensive

and up-to-date overview of DIY MP3

projects on the World Wide Web.

Starting from this site, we visited a

number of MP3 addresses related

small portable players. This time, we

have intentionally omitted the larger

types of units (those using PC moth-

erboards).

The MP3 PuBliC from MP3ar [2] is a

very nice example of an MP3 player.

It involves a small printed circuit

board that is slightly larger than a

Elektor Electronics

6/2001

ELECTRONICS ON-LINE

and a display. It is interesting to spend a bit of

time studying and comparing the designs,

since different approaches have been taken

based on various processors. Here again, as

with most player designs, all hardware and

software information is freely available.

Audio Affinity 2000 [6], which comes from a

number of electronics types in Florida, is a

special project that is just getting started.

The unusual feature of this project is that it

supports both recording and playback in the

MP3 format. Up to now, there isn’t much in

the way of concrete items to be seen on this

site, but you might want to take a look at it

from time to time in the future.

The ELM MP3 Player [7] is a design that

looks like a commercial product, at least to

judge by the prototype made by its Japanese

designer. This small player uses Smartmedia

memory cards to store the music data. The

circuit is built around an Atmel controller and

a Micronas DSP/DAC chip set.

Finally, we looked at a player that evidently

comes from the ﬁnal term project of a pair of

students (Peter D’Antonio and Daniel Riiff).

Their design, which goes by the name ‘ EE

476, Final Project: Portable MP3 Player’ [8],

is still in the prototype phase, but its overall

capabilities are quite attractive. If the two

gentlemen succeed in reducing all of this to

a printed circuit board of acceptable dimen-

sions, it will certainly be an interesting

player. The special feature of this player is

that it uses ﬂash memory cards.

decoding is handled by an

MAS3507D or STA013 IC. A fairly

large LCD panel (128 × 64 pixels)

simpliﬁes communications with this

device. The photos show a relatively

small printed circuit board, so we

can rightly consider this to be a

portable player. This unit currently

works with a CD-ROM drive, but it is

the intention that it will shortly be

able to work with a hard disk drive

as well.

The YAMPP site [5] is another loca-

tion where a lot of work is going on.

The name stands for ‘Yet Another

MP3 Player’. Here you will ﬁnd sev-

eral different hardware designs,

some of which are still under devel-

opment. All of the players have con-

nectors for an IDE hard disk drive

(015065-1)

Website url’s

[1] MP3Projects:

http://www.mp3projects.com/

[2] MP3 PuBliC:

http://www.mp3ar.com/

[3] MPRJ:

http://www.pjrc.com/tech/mp3/

[4] MoP3:

http://www.geocities.com/SiliconValley/

Circuit/3150/index.html

[5] YAMPP:

http://www.myplace.nu/mp3/

[6] Audio Affinity 2000:

http://www.audioaffinity.com/

[7] ELM MP3 Player:

http://elm-chan.org/reports/mpc/

report_e.html

[8] Portable MP3 Player:

http://instruct1.cit.cornell.edu/courses/

ee476/FinalProjects/s2000/

peterdan/ﬁnal.htm

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