PART B

 

Describe the tone pattern you hear (i.e., high or low, how long, etc.).

It is a cycle of three different tunes from high to low. Tones last a couple of seconds and have a break of couple of seconds between the tunes.

✔

 

 

PART C

 

Tell a member of the teaching team what your song is (or better yet, play it for us).

Absolutely Cuckoo

✔

 

Does this code play all the songs in all the directories of the SD card? If not, which songs does it play? How does it keep from playing the text file?

It plays all the songs in the directory. It checks the format of files it tries to play and only plays .mp3-ending files.

✔

 

Change the Song (or Simple_MP3_V2) program to save the current volume setting in your EEPROM, then fetch and set that value during initialization. Note that the first max_num_songs * max_name_len (in this case, 520) bytes of the EEPROM are used to store file names, so don't overwrite those. 

 

I need to remove:

     #define mp3_vol = 175

 

And add:

     EEPROM.write(0x1000, 210);

     int mp3_vol = EEPROM.read(0x1000);

 

✔

 

 

PART D

 

Draw us a quick sketch of what your circuit looks like.

✔

 

What are the pros and cons of using this method?

Pro is that it sees only the actual click.

A con is that if the button is pressed quickly multiple times, it doesn't register everything.

✔

 

 

Now, take what you learned to make an interrupt driven pause function for your Barebones MP3 player!

 

/*

 * example sketch to play audio file(s) in a directory, using the mp3 library

 * for playback and the arduino sd library to read files from a microsd card.

 * pins are setup to work well for teensy 2.0. double-check if using arduino.

 * 

 * originally based on frank zhao's player: http://frank.circleofcurrent.com/

 * utilities adapted from previous versions of the functions by matthew seal.

 *

 * (c) 2011, 2012 david sirkin sirkin@cdr.stanford.edu

 *                & akil srinivasan akils@stanford.edu

 */

 

// ---- includes and defines ------------------------------------------------

 

// first step is to include (arduino) sd, eeprom and (our own) mp3 libraries.

 

#include <SD.h>

#include <SPI.h>

#include <EEPROM.h>

 

#include <mp3.h>

#include <mp3conf.h>

 

// include the adafruit pcd8544 & gfx libraries for a nokia 5110 graphic lcd.

 

#include <Adafruit_GFX.h>

#include <Adafruit_PCD8544.h>

 

// setup microsd and decoder chip select pins, and the decoder-specific pins.

 

#define sd_cs         17        // 'chip select' line for the microsd card

 

#define mp3_cs        A0        // 'command chip select' connect to cs pin

#define mp3_dcs       A1        // 'data chip select' connect to bsync pin

#define mp3_rst       -1        // 'reset' connects to decoder's reset pin

#define mp3_dreq      A2        // 'data request line' connect to dreq pin

 

// now assign pins for the graphic lcd (carried over from the etch-a-sketch).

 

#define lcd_dc        A4        // 'data/command input' connect to d/c pin

#define lcd_cs        A3        // 'slave chip select' connects to  cs pin

#define lcd_rst       -1        // 'reset' connects to graphic lcd rst pin

 

// 'read_buffer' is the amount of data read from microsd and sent to decoder.

// it's probably best to keep this a factor of 2, up to about 1kb (2kb is the

// max). you might change this if you experienced skips during song playback.

 

#define read_buffer  512        // size (bytes) of the microsd read buffer

#define mp3_vol      175        // default volume. range min=0 and max=254

 

// file names are 13 bytes max (8 + '.' + 3 + '\0'), and the file list should

// fit into the eeprom. for example, 13 * 40 = 520 bytes of eeprom are needed

// to store a list of 40 songs. if you use shorter file names, or if your mcu

// has more eeprom, you can change these.

 

#define max_name_len  13

#define max_num_songs 40

 

// id3v2 tags have variable-length song titles. that length is indicated in 4

// bytes within the tag. id3v1 tags also have variable-length song titles, up

// to 30 bytes maximum, but the length is not indicated within the tag. using

// 60 bytes here is a compromise between holding most titles and saving sram.

 

// if you increase this above 255, look for and change 'for' loop index types

// so as to not to overflow the unsigned char data type.

 

#define max_title_len 60

 

// ---- global variables ----------------------------------------------------

 

// instantiate a graphic lcd object using the pins that we #define'd earlier.

// comment out the graphics lines to save memory if you're not using the lcd.

 

// Adafruit_PCD8544 lcd = Adafruit_PCD8544(lcd_clk, lcd_din, lcd_dc, lcd_cs, lcd_rst);

Adafruit_PCD8544 lcd = Adafruit_PCD8544(lcd_dc, lcd_cs, lcd_rst);

 

// 'File' is a wrapper of the 'SdFile' data type from the sd utility library.

 

File sd_file;                   // object to represent a file on a microsd

 

// store the number of songs in this directory, and the current song to play.

 

unsigned char num_songs = 0, current_song = 0;

 

// an array to hold the current_song's file name in ram. every file's name is

// stored longer-term in the eeprom. this array is used in 'sd_file.open()'.

 

char fn[max_name_len];

 

// an array to hold the current_song's title in ram. it needs 1 extra char to

// hold the '\0' that indicates the end of a character string. the song title

// is found in 'get_title_from_id3tag()'.

 

char title[max_title_len + 1];

 

// the program runs as a state machine. the 'state' enum includes the states.

// 'current_state' is the default as the program starts. add new states here.

 

enum state { DIR_PLAY, MP3_PLAY, PAUSED };

state current_state = DIR_PLAY;

 

//---- module functions -----------------------------------------------------

 

// you must open a song file that you want to play using 'sd_file_open' prior

// to fetching song data from the file. you can only open one file at a time.

 

void sd_file_open() {  

  // first, find the file name (that's stored in eeprom) of the current song.

 

  get_current_song_as_fn();

 

  // then open the file using the name we just found (stored in 'fn' global).

 

  sd_file = SD.open(fn, FILE_READ);

 

  // find the current song's title tag (if present) then print it to the lcd. 

 

  print_title_to_lcd();

}

 

// read a number of bytes from the microsd card, then forward them to the Mp3

// library's 'play' function, which streams them out to the decoder chip.

 

void mp3_play() {

  unsigned char bytes[read_buffer]; // buffer to read and send to the decoder

  unsigned int bytes_to_read;       // number of bytes read from microsd card

 

  // first fill the 'bytes' buffer with (up to) 'read_buffer' count of bytes.

  // that happens through the 'sd_file.read()' call, which returns the actual

  // number of bytes that were read (which can be fewer than 'read_buffer' if

  // at the end of the file). then send the retrieved bytes out to be played.

 

  // 'sd_file.read()' manages the index pointer into the file and knows where

  // to start reading the next batch of bytes. 'Mp3.play()' manages the index

  // pointer into the 'bytes' buffer and knows how to send it to the decoder.

 

  bytes_to_read = sd_file.read(bytes, read_buffer);

  Mp3.play(bytes, bytes_to_read);

 

  // 'bytes_to_read' is only smaller than 'read_buffer' when the song's over.

 

  if (bytes_to_read < read_buffer) {

    sd_file.close();

 

    // if we've been in the MP3_PLAY state, then we want to pause the player.

 

    if (current_state == MP3_PLAY) {

      current_state == PAUSED;

    }

  }

}

 

// continue to play the current (playing) song, until there are no more songs

// in the directory to play. 2 other sd library methods (that we haven't used

// here) can help track your progress while playing songs: 'sd_file.size()' &

// 'sd_file.position()'. you can use these to show say, the percent of a song

// that has already played.

 

void dir_play() {

  if (sd_file) {

    mp3_play();

  }

  else {

    // since 'sd_file' isn't open, the recently playing song must have ended.

    // increment the index, and open the next song, unless it's the last song

    // in the directory. in that case, just set the state to PAUSED.

 

    if (current_song < (num_songs - 1)) {

      current_song++;

      sd_file_open();

 

    }

    else {

      current_state = PAUSED;

    }

  }

}   

 

void pause() {

  if(current_state == PAUSED) {

    current_state = DIR_PLAY;

  }

  else {

    current_state = PAUSED;

    Mp3.clear_buffer();

  }

}

 

// ---- setup and loop ------------------------------------------------------

 

// setup is pretty straightforward. initialize serial communication (used for

// the following error messages), mp3 library, microsd card objects, then the

// graphic lcd. then open the first song in the root library to play.

 

void setup() {

  attachInterrupt(0, pausePlay, FALLING);

 

  // if using a graphic lcd, initialize with contrast, then setup the screen.

 

  lcd.begin(60);

  lcd.display();

  delay(500);

 

  lcd.clearDisplay();

  lcd.print("Barebones Mp3!");

  lcd.display();

  delay(500);

 

  // initialize the mp3 library, and set default volume. 'mp3_cs' is the chip

  // select, 'dcs' is data chip select, 'rst' is reset and 'dreq' is the data

  // request. the decoder sets the 'dreq' line (automatically) to signal that

  // its input buffer can accommodate 32 more bytes of incoming song data.

 

  // the decoder's default state prevents the spi bus from working with other

  // spi devices, so we initialize it first.

 

  Mp3.begin(mp3_cs, mp3_dcs, mp3_rst, mp3_dreq);

  Mp3.volume(mp3_vol);

 

  // initialize the microsd (which checks the card, volume and root objects).

 

  sd_card_setup();

 

  // putting all of the root directory's songs into eeprom saves flash space.

 

  sd_dir_setup();

 

  // the program is setup to enter DIR_PLAY mode immediately, so this call to

  // open the root directory before reaching the state machine is needed. 

  sd_file_open();

  attachInterrupt(0, pausePlay, FALLING);

}

 

// the state machine is setup (at least, at first) to open the microsd card's

// root directory, play all of the songs within it, close the root directory,

// and then stop playing. change these, or add new actions here.

 

// the DIR_PLAY state plays all of the songs in a directory and then switches

// into PAUSED when done. the MP3_PLAY state plays one specific song and then

// switches into PAUSED. this sample player doesn't enter the MP3_PLAY state,

// as its goal (for now) is just to play all the songs. you can change that.

 

void loop() {

  switch(current_state) {

 

    case DIR_PLAY:

      dir_play();

      break;

 

    case MP3_PLAY:

      mp3_play();

      break;

 

    case PAUSED:

      //mp3_pause();

      break;

  }

}