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This is a follow up to an earlier Instructable for attaching the guts of a cheap clip MP3 player to an Arduino.
http://www.instructables.com/id/MP3-Interface-for-Arduino-Cheap-and-Easy/
The previous Instuctable showed how to use the Arduino to control all of the functions of the MP3 player: volume increase and decrease, next and previous MP3 file, play or pause. The previous Instructable also showed how to disassemble these little clip players and salvage the cool parts within.
This Instructable makes the attaching the MP3 player to the Arduino more straight forward and a lot cleaner. In this installment, we will make a single sided Arduino shield. (You can use this same process for your other Arduino projects.) If you are into electronics and like prototyping, being able to fab your own PCB can be a great addition to the personal tool belt.
So why do this? Why attach an MP3 player to an Arduino? Think about responsive talking toys (how about a screaming/moaning version of Operation?), interactive dioramas, museum touch-and-explain displays...
PLEASE SEE THE LAST STEP FOR SOME FOLLOW-ON INFORMATION CONCERNING THE LC2093-B.
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Signing UpStep 1Design the Board
There are a limited number of connections that we need to make between the MP3 player and the Arduino. These connections are:
1. 3.3V from the Arduino to power the MP3
2. Ground. So there is a common ground between the two devices.
3. Vol- on the MP3 attaches to pin 8 on the Arduino.
4. Vol+ on the MP3 attaches to pin 9 on the Arduino.
5. PLAY/PAUSE on the MP3 attaches to pin 10 on the Arduino.
6. Pins 6 and 7 of the Arduino are use to control a 74HC244 tristate driver to allow NEXT and PREV selection of MP3 files.
(Note, the comments on the previous Instructable suggested that the analog switches in that design be replaced with some more universally available part. I think the 74HC244 takes care of that: it is cheap, universally availble thru electronics distributors, handles both selections in one device and handles the 5V Arduino to 3.3V MP3 conversion.
See the previous Instructable for the explanation of how the design works...)
I use EagleCad. Because of the screwball spacing of the Arduino connector, I just start with the Arduino standard shield design and modify to suit my application. You can find a standard Eagle shield design at:
http://arduino.cc/en/Main/ArduinoProtoShield
Attached are my files.
1. 3.3V from the Arduino to power the MP3
2. Ground. So there is a common ground between the two devices.
3. Vol- on the MP3 attaches to pin 8 on the Arduino.
4. Vol+ on the MP3 attaches to pin 9 on the Arduino.
5. PLAY/PAUSE on the MP3 attaches to pin 10 on the Arduino.
6. Pins 6 and 7 of the Arduino are use to control a 74HC244 tristate driver to allow NEXT and PREV selection of MP3 files.
(Note, the comments on the previous Instructable suggested that the analog switches in that design be replaced with some more universally available part. I think the 74HC244 takes care of that: it is cheap, universally availble thru electronics distributors, handles both selections in one device and handles the 5V Arduino to 3.3V MP3 conversion.
See the previous Instructable for the explanation of how the design works...)
I use EagleCad. Because of the screwball spacing of the Arduino connector, I just start with the Arduino standard shield design and modify to suit my application. You can find a standard Eagle shield design at:
http://arduino.cc/en/Main/ArduinoProtoShield
Attached are my files.
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http://shop.moderndevice.com/products/rbbb-kit
or Solarbotics Arduweeny
http://www.solarbotics.com/product/kardw/
http://www.solarbotics.com/product/18950/
or Teensy
http://www.pjrc.com/teensy/
Or the Minis... Lots of small form factor Arduinos out there. You could just breadboard with one of those.
Does the VS1000 datasheet have information on the IIC interface? Our LC2093 might well retain the same functions, or at least the same data format....
If we knew how to make it respond then getting an Ardu' to try all 127 I2C addresses until it received a response would not be too difficult!
I continue to await my shipment from HongKong!
PS nice shield. I'm not really familiar with octal buffer chips. Any clues the theory of how you make this setup work?
http://www.vlsi.fi/fileadmin/app_notes/vlsi/guide_vs1000.pdf
http://www.vlsi.fi/fileadmin/datasheets/vlsi/vs1003.pdf
VLSI's documentation is very extensive. Poke around their website if you get a chance. If I get a chance I will take a look at the I2C also... it has been a number of years since I used I2C though, so you are probably way ahead of my re-learning curve.
I used the 74HC244 to do two things, provide the 5V to 3.3V conversion and act as a one-way switch. If either section of the 244 is in tri-state(high impedance mode), the outputs are just very high resistance. The high impedance mode is selected by putting the controlling Arduino pins in INPUT mode. That allows the two pull-up resistors to bring the 244 controls to 3.3V.
To switch either section of the 244 into conducting mode, the Arduino pins are pulled low and made to be OUTPUT. This turns the 244 from high impedance mode to conducting mode.
Sadly, although they look identical to yours, the ones I have do not have the same chip. They have a 48-pin blob of epoxy! Not too likely to find a datasheet for that....
None of the controls go to ground - you can trace the connections back to 6 pins of the "blob" and the controls work from combinations of these - I reckon your buffer chip approach should work fine but it will need a little tweaking.
Tantilisingly, there are RX and TX pins marked on the board that trace back to the blob, but I just can't get it to talk to me! I've tried various baud rates but I'm not even getting noise through. Ho Hum. It would have been nice.
dreschel@verizon.net
Sorry you had to wait so long to try this out. (I really only got involved with this to help one of my nephews with a senior design project.)
I got my player from eBay last week, but I haven't gotten it to work yet. When I plug it into any of my Macs they say that it is drawing too much power from the USB port. Not a big deal. It uses a chip bonded directly to the PCB, ie. not a discrete IC btw, but the other side is identical to the above pictures.
Another avenue I'm pursuing atm. is to use my Ethernet shield to send a wake on lan packet to the Mac to wake it in the morning, and then have it set to play something in iTunes with a script. I have speakers hooked up to Airport Express devices throughout the house so it can route the music to the bedroom. Once I have results from either of the two methods I'll post them.
I don't plan on selling the PCB BUT I will post a set of Eagle files for a two layer thru hole version that you will be able to submit directly to Dorkbot PCB.
http://dorkbotpdx.org/wiki/pcb_order
Dorkbot is fantastically cheap and has phenomenal quality. You will have to wait a week or two but you won't do better (I recently had 3 small boards from them for $8 total including shipping!)
Give me a day or two.
Arduino:
http://www.arduino.cc/
Arduino Shield:
http://arduino.cc/en/Main/ArduinoShields