* MP3 Shield * - Rogue Robotics rMP3

L and R provide accurate activity for that sort of thing :wink: Why not branch from there for both output and route to analog input in the Arduino? I don't know what the upper or lower values for those pads are (maybe in the docs?), but it's surely a valid option. Just make sure it doesn't exceed the pins impedance.

You mean speaker L & R?
That requires all the annoying circuitry in between to get that to work...
I suppose i am more asking about a frequency visualiser which is more complicated...

Mowcius

Not necessarily. The analog input in the Arduino can take any value between 0v - 1v (I believe), so, as long as you limit the voltage (using the correct resistance), then you have a simple variable source right there. The biggest issue is making sure your querying of that source doesn't use the potential that would otherwise drive your speaker output (though you could increase that with an amp).

0v - 1v (I believe)

You mean 0 - 5v (well it's more like 0 - 5.5 but that's pushing it a bit.)

Yeah, 5v... That's what I meant :wink: Well, you're okay, then, seeing as 5v is the maximum voltage anywhere past the regulator! Hook even one of those pads into the Arduino and use it as an input. Actually, you could also average the highs and lows so as to get better results, as those highs and lows will be quite similar in value.

You have to be careful when using audio signals. The output from the rMP3 on the L and R pins are actually AC signals (because of the filter capacitors on the outputs). This means that the voltage with respect to ground on those pins can be negative, if you connect them to the analog inputs on the Arduino. This can damage the ADC on the Atmel chip.

You could introduce a DC offset, but that will require extra components which I think mowcius is trying to avoid. :slight_smile:

I'd stay away from connecting the audio output to one of the analog inputs, unless you know what you're doing.

mowcius - your wish is my command. Here is the updated documentation on the input interface:

http://www.roguerobotics.com/wikidocs/rmp3/documentation/input_interface

b

Hadn't thought about it being AC (which should be as obvious as the nose on my face), but it's nothing that a handful of diodes couldn't fix. In fact, one could always route the negative edge to a separate pin as a positive feed. :stuck_out_tongue:

mowcius - your wish is my command. Here is the updated documentation on the input interface:

http://www.roguerobotics.com/wikidocs/rmp3/documentation/input_interface

Oooh, I do feel powerful :stuck_out_tongue:

I presume it is still on the list but what do all the other pads do? From the looks of it, some could be for an FTDI header?

You could introduce a DC offset, but that will require extra components which I think mowcius is trying to avoid.

Aye, I will look into it with as few components as I can get away with though :stuck_out_tongue:

Mowcius

All the connections are described in detail here:

http://www.roguerobotics.com/wikidocs/rmp3/documentation/connectors

It's got:

Arduino compatible shield connectors
FTDI/SFE-DEV-09115 cable connector
Digital trigger connector (trigger with digital inputs)
... among others

b

I was wondering if you guys plan on coming up with a cheaper version of your MP3 shield. Like Sparkfuns?

Sparkfun's MP3 breakout is far less functional. I really had to search high and low for a "high quality" and flexible MP3 board for my JukeBox project I'm building. There just aren't that many out there. It was pure luck that this one was already arduino compatible, because I was quite prepared to fashion one into an arduino ready product.

Sometimes less is more. :wink:

for example

I never had a problem with that shield - until I tried to use it. You pay less for more work (and more headaches, and more technical jargon, and so on). If that turns your crank, go for it. The adage always holds true: "You get what you pay for".

I'll put forward a challenge to you though. If you can explain the differences between that board and the Rogue Robotics rMP3 shield, I'll send you a free rMP3 shield. [Offer only valid for Sannin :wink: ]

b

P.S. I'll steer clear of the fact that they also use Arduino in their product name when it clearly isn't endorsed by the Arduino Team.

It's awesome!!

sorry if the question is silly...

I am building a small installation where PIR sensor will detect presence and start playback of two audio files simultaneously at two different locations.

If I stack two rMP3 players on top of one arduino board, will both of the players start playback simultaneously when 'play' command is sent through pin 6, or do I need to rewire pins on the second shields and have a second 'play' command sent through the rewired pin.

thanks,
M.

There's never a silly question.

Actually, that's a clever question. If you have two rMP3's stacked, using the same serial pins, you could send commands to both of them simultaneously. Works great (I even tested it out here). Just don't expect to get any meaningful data back from the rMP3s - they will both be vying for control of the Arduino receive pin.

Here's the code I used:

#include <RogueMP3.h>
#include <NewSoftSerial.h>

NewSoftSerial rmp3_s(6, 7);

RogueMP3 rmp3(rmp3_s);

void setup()
{
  rmp3_s.begin(9600);
  
  rmp3.sync();
  rmp3.playfile("/ump3test.mp3");
}

void loop()
{
}

In theory, you could stack 10 rMP3's up on the Arduino, and send a single command to start them all at the same time. Have the same named file on each card play a separate instrument track from a symphony, and they would all play together. Of course, you'd need a 10 channel stereo mixer to mix all the outputs, but that's another story.

b

Very nice. I like the ease of programming. But don't you think it's too pricy? I mean there's the Arduino MP3 Shield (micro4you.com is for sale | HugeDomains).

This costs only 30 dollars, almost 50 dollars less than the rMP3....

DeadEye - Same issue as Sannin (I guess he/she didn't want a free rMP3).

That board is just an MP3 decoder + SD card socket. It doesn't do anything. You still need a controller.

So, $30 for that board, plus $30 for an official Arduino, and you're at $60. Then you will have to do the interface between the SD card and the MP3 decoder - tying up the Arduino which could be doing a lot of other things.

I'm definitely not putting down that product. It's great if you want to learn how to use SD cards and the MP3 decoder. Go nuts if that's what you want.

The rMP3 can run on it's own, or can be controlled by an Arduino (or another microcontroller) with very little interaction.

Bottom line:
You'll need more than just that $30 board to get MP3's playing. And you may not have much space/time left on your Arduino for anything else.

b

Oh, sorry didn't notice that. If that's the case then I'm definitely buying this one over the MP3 Shield. Seriously, though, I thought the MP3 Shield didn't need any other parts. If what you say is true then it seems the rMP3 is way better.

Thanks for the explanation.

Can you tell me what are the differences between the uMP3 and rMP3?