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| BASIC |
So you've seen other
people's MP3 players and you're thinking, "Hmmm I bet I can do
that!" Well, chances are that if you have a little bit of digital
electronics skills, some extra cash, and a LOT of free time... you
probably can. However, many people just jump right into it without
planning it out fully. There are a few questions that have to be asked...
- So, what's involved in building an MP3 player?
- What is the source of the MP3 files?
- What microprocessor are you going to use?
- What features do I want?
- What overall parts do I need?
- How do I assemble everything together?
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So, what's involved
in building an MP3 player?
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| If you
can answer all of these questions easily, then you shouldn't have
any real difficulty in designing and building your own MP3 player.
If you're stuck on any of these questions, you can simple see how
other people did their project to get good ideas. |
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What
is the source of the MP3 files?
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| In other
words, where are the MP3 files going to be retrieved? In most cases,
people want the MP3 files to come off of a compact disc or a hard
drive because of their mass storage capabilities. This method is extremely
complicated and requires reading through hundreds of pages of standards
and technical documents. Fortunately there's already made software
code and schematics available to make this process much easier.
And for portable reasons, some might decide on using a flash memory
card (like 90% of all portable commercial players). Unfortunately
getting a hold of the materials needed to use and program a memory
card can be difficult and far too expensive.
Another simple (yet, not very practical) option is to download
the MP3 from the computer parallel port. This method should probably
be your first choice since you don't need a lot of hardware and
it's good for "testing" your player. Once your player
is capable of decoding MP3 files from the parallel port into music
(thus performing a successful test) you can then add a CD-ROM or
hard drive interface.
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| What
microprocessor are you going to use? |
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This is probably going to
be the most critical decision about your player that you're going
to make. It will require reading manuals and doing research to try
to decide which processor is right for you. When choosing a processor
you need to keep these things in mind...
- Can I get the processor and how much does it cost?
- If needed, can I get a hold of a C compiler for it?
- Does it have enough I/O pins?
- If needed, can I interface an IDE device to it?
- Am I able to easily mount it to a project board? PLCC or PQFP?
Remember, the processor is going to be responsible for taking the
MP3 data from the source and sending it to the MP3 decoder chip.
If needed, it will also be responsible for controlling a small keyboard,
LCD display, and I2C communication to and from the MP3 decoder chip.
However... if you just want to make a simple MP3 player that will
decode MP3 files coming out of the computer parallel port, you may
not need a processor at all.
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| What
features do I want? |
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| If you want to be really fancy,
you can implement additional features to the MP3 player... features
that will make it more practical, and user friendly. Here's a list
of ideal features that your player should have:
- Some kind of display or LCD panel to show which MP3 file is currently
being played, what's the current status of the song (time remaining,
etc.), whether the song is playing in MONO or STEREO. The same kind
of information that WinAmp would display (maybe not as fancy though).
- A simple keyboard interface with all the buttons that are similar
to a regular CD-player (play, stop, next, pause, volume, etc.)
- A variety of inputs and outputs (outputs to a stereo system,
headphone jack, parallel port connector to download songs (if a
hard drive is being implemented), remote control, etc.
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| What
overall parts do I need? |
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| Here's a sample of what your
block diagram should look like assuming you're going to build the
ideal MP3 player:
Here are some example parts that you need to build your player...
I'll list more than one option under each heading:
SOURCE:
- regular computer IDE CD-ROM drive
- regular computer IDE hard drive
- DB25 female connector for parallel port
MAIN PROCESSOR:
- Microchip PIC processor (make sure it has enough I/O pins)
- Motorola 68HC11
- Motorola 68000 series
- Atmel AT90S8515
- Texas Instruments TMS320C31
MP3 DECODER CHIP:
- Micronas Intermetall MAS3507D (most popular)
- STMicroelectronics STA013
- Cirrus Logic EP7209
STEREO DAC:
- Micronas Intermetall DAC3550A (most popular)
- Crystal Semiconductor CS4334
- Burr-Brown PCM1723
LCD DISPLAY:
- really any plain LCD panel will do, make sure it has enough room
to display all the information you want, and MAKE SURE you have
documentation with it.
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| How
do I assemble everything together? |
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| This part of the design is
really up to which parts you decide to choose. This is where everything
starts to get complicated and you really should have knowledge of
microprocessor interfacing and troubleshooting. Sure, anybody can
get to the point of knowing which parts to use, but actually putting
them all together is what it all comes down to.
Knowledge of soldering or wire wrapping, digital glue logic, noise
filters and decoupling, ability to manipulate signals, measurements
and readings, machine-level programming, technical document comprehension,
etc. If you are unable to perform these very simple electronic tasks,
then you are not ready to build your project. Just one simple mistake
can go unnoticed for months and you're left wondering why your player
isn't performing. Even if you have somebody else's complete schematics
and software code, you will not be able to build the device unless
you understand how it works.
A hardware MP3 player should only be made by a skilled electronics
hobbyist.
Okay... now that you know the basics and what's involved, I've
provided all kinds of technical information relevant to the creation
of an MP3 player in the DOCUMENTS section. I've also provided links
to outside projects which may, or may not, contain schematics and
software code.
Good Luck!
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