Arduino uno to MP3 card

Discussion in 'Embedded Systems and Microcontrollers' started by cmjb13, Nov 29, 2015.

  1. cmjb13

    Thread Starter Member

    Mar 18, 2015
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    I purchased a MP3 player card to connect to the arduino uno

    Seen here:
    http://www.mdfly.com/products/sd-card-mp3-player-module-rs232-ttl.html

    I have it hooked to the arduino as follows

    MP3 PIN 15 (RXD) to Arduino TX
    MP3 PIN 19 (GND) to Arduino Analog GND
    MP3 PIN 20 (VDD) to Arduino 5v

    I have a pair of "old school" computer speakers with external power supply. I have not stripped any wires. It's stated I need 3 caps to between the arduino pins and mp3 module pins. Do I use a breadboard to get this part working or can I use the jumper wires I currently have?

    I'm so close, any help is appreciated.

    Thanks.
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    You are not making sense.

    I have looked at the spec sheet, there is no mention of caps.
    Obviously you are getting info from more than one source. Which is fine. The problem is that the rest of us don't know what you are talking about.
     
  3. cmjb13

    Thread Starter Member

    Mar 18, 2015
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    My apologies. Let me clarify.

    I have a stepper motor that is currently connected to an Arduino Uno
    The Arduino Uno works fine in controlling the motor
    I would like to add some sounds for when the motor spins, so I purchased an .mp3 card.
    I have the .mp3 card connected to the Arduino Uno with 3 jumpter wires to the pins mentioned above.
    I was told I would need to use a pair of external computer speakers to hear the sound by adding 3 capacitors in series in-between the sound board and the amplifier (left, right, and audio ground). The capacitors will block DC voltage & current while allowing the AC audio signal through.

    Problem is all I have right now are jumper wires. Do I need to use a breadboard for the caps to get this working properly?

    Thanks.
     
  4. ISB123

    Well-Known Member

    May 21, 2014
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    They remove DC offset.

    You can solder them directly on the wire in series.
     
  5. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    Yeah, the caps sound like the dc blocking caps.

    You could do it on breadboard.

    You could get some wire and just wind the wire around the legs of the cap and melt some solder on the wound wire. If you want it to look semi pro, use shrink wrap, otherwise put some electrical tape on it.

    Assuming speakers still have the 3.5 mm male plug, I suggest you get a 3.5 mm female socket. The female socket on one end, wires on the other end. You can get patch cable that got female on one end and male on the other end, chop off the male, strip the wires (check which wire is right, left and ground), breadboard or solder the caps, connect to your mp3 player board.
     
  6. cmjb13

    Thread Starter Member

    Mar 18, 2015
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  7. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    http://www.pccables.com/products/05046.html
    ^ that one is the 3.5 mm female to RCA male. You don't need that. You are not going to do anything with RCA.

    http://www.cablewholesale.com/produ...um=cpc&utm_term=10A1-01206&utm_campaign=3.5mm Stereo Extension Cable, 3.5mm Male to 3.5mm Female, 6 foot
    This is the type I mentioned last. It has 3.5 mm female on one end (I suggested to plug 3.5 mm male from speakers into it) and 3.5 mm male on the other end. In your case you don't need the male plug so I suggested to cut it off, strip the wire, solder on the caps, connect the other end of caps to the mp3 player board.

    Or you can go getto and just chop off the male plug on the speakers.


    Soldering cap like this:
    [​IMG]


    However. You don't need to cut the cap legs short. Just take the cap, don't cut the legs, wind the wire around the leg, melt the solder over the area where wire is wound around the leg. If you are going to shrink wrap the soldered area, put the shrink wrap on the wire before you solder, also move the shrink wrap well back from the soldering area because the wire will heat up and the shrink wrap will shrink. My advice for this type of soldering is to use soldering gun. Soldering iron is just too fine for this basic work.

    Also. About caps. The usual soda can shaped caps have polls, plus and minus, I don't think you need this type of cap. If I were you I would use just plain ceramic caps, this way you don't need to worry about polarity. Take the voltage output of the mp3 player and add a couple of volts to it, the spec sheet says it takes 6-12 volts for power, so figure 12-16 volt rated capacitors.
     
    Last edited: Nov 29, 2015
  8. be80be

    Senior Member

    Jul 5, 2008
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    If you look at the sheet that comes with it there's caps on the spearker output made on the board they say c17 and c18 it shows them in the spec sheet
     
  9. shteii01

    AAC Fanatic!

    Feb 19, 2010
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  10. be80be

    Senior Member

    Jul 5, 2008
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    Well I don't own one but yes it shows them If the op looks at his board and traces the speaker pin he should see them. And tell If there as shown.
     
  11. cmjb13

    Thread Starter Member

    Mar 18, 2015
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    Pic attached, so if there's caps on the board (which I didn't even notice before), can I take the male end of the extension cable, cut it off. strip the wire, and solder directly to pins 17 & 18 on the mp3 board?
     
    Last edited: Nov 29, 2015
  12. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    It looks like you are all set then. No need for extra caps.
     
  13. be80be

    Senior Member

    Jul 5, 2008
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    There on the board as it shows them. I have seen boards that had the pads and you add them but you have them on that board.
    You can solder your cord if you want I would wire wrap them and solder the the wire myself so I could change it later if needed.
     
  14. cmjb13

    Thread Starter Member

    Mar 18, 2015
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    I went ahead and purchased the extension cable.

    I will connect the male speaker plug to the female end of this extension cable. I will cut the male side off, strip the wires, and solder

    mp3 card DC pin 20 will connect to arduino 5V
    mp3 card GND pin 19 will connect to arduino GND
    mp3 card RXD pin 15 will connect to arduino TX
    mp3 card HPR pin 17 (Audio R) soldered to right striped speaker wire
    mp3 card HPL pin 18 (Audio L) soldered to left striped speaker wire

    Is there any way to tell once the wires are stripped to distinguish between left and right speaker wire?
     
  15. be80be

    Senior Member

    Jul 5, 2008
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    Ohm them out here a pic
    [​IMG]
     
  16. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    That could be a problem.
    Manufacturer says the device should be powered by 6-12 volts. 5 volts might be enough, or not.
     
  17. cmjb13

    Thread Starter Member

    Mar 18, 2015
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    I tested with the DC pin to Arduino 5V and it does get visual power, but obviously can't fully test until the speakers are connected.
     
  18. cmjb13

    Thread Starter Member

    Mar 18, 2015
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    So it appears that

    White is right
    Red is left
    Ground

    Should I solder the ground from the 3.5 mm cable to the mp3 card or just connect left and right and use the jumper wire for mp3 ground to arduino ground?
     
  19. be80be

    Senior Member

    Jul 5, 2008
    431
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    You tie ground to ground make sure all are tied
    You can supply 6 volts to the mp player but don't tie it to the 5 volt pin on the arduino
    the RX and TX pins are
    so there not going to be higher then 5 volts more like 3.3 volts
    Just tie all grounds.
    If you use the power plug with a wall wart you could get power from the Vin pin it's at the power plug voltage
    arduinomp.png
     
    Last edited: Nov 29, 2015
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