Bonjour,
J’utilise un programme arduino qui permet de lire des fichiers sur une carte SD grâce au “MP3 Player Shield”. Mais j’ai du mal à comprendre le code de ce fichier malgré qu’il y est des commentaire en anglais pour m’aider.
/* Pin setup */
#define TRIGGER_COUNT 9
int triggerPins[TRIGGER_COUNT] = {0, 1, 5, 10, A0, A1, A2, A3, A4};
int stopPin = A5; // This pin triggers a track stop.
int lastTrigger = 0; // This variable keeps track of which tune is playing
void setup()
{
/* Set up all trigger pins as inputs, with pull-ups activated: */
for (int i=0; i<TRIGGER_COUNT; i++)
{
pinMode(triggerPins[i], INPUT_PULLUP);
}
pinMode(stopPin, INPUT_PULLUP);
initSD(); // Initialize the SD card
initMP3Player(); // Initialize the MP3 Shield
}
// All the loop does is continuously step through the trigger
// pins to see if one is pulled low. If it is, it'll stop any
// currently playing track, and start playing a new one.
void loop()
{
for (int i=0; i<TRIGGER_COUNT; i++)
{
if ((digitalRead(triggerPins[i]) == LOW) && ((i+1) != lastTrigger))
{
lastTrigger = i+1; // Update lastTrigger variable to current trigger
/* If another track is playing, stop it: */
if (MP3player.isPlaying())
MP3player.stopTrack();
/* Use the playTrack function to play a numbered track: */
uint8_t result = MP3player.playTrack(lastTrigger);
// An alternative here would be to use the
// playMP3(fileName) function, as long as you mapped
// the file names to trigger pins.
if (result == 0) // playTrack() returns 0 on success
{
// Success
}
else // Otherwise there's an error, check the code
{
// Print error code somehow, someway
}
}
}
// After looping through and checking trigger pins, check to
// see if the stopPin (A5) is triggered.
if (digitalRead(stopPin) == LOW)
{
lastTrigger = 0; // Reset lastTrigger
// If another track is playing, stop it.
if (MP3player.isPlaying())
MP3player.stopTrack();
}
}
// initSD() initializes the SD card and checks for an error.
void initSD()
{
//Initialize the SdCard.
if(!sd.begin(SD_SEL, SPI_HALF_SPEED))
sd.initErrorHalt();
if(!sd.chdir("/"))
sd.errorHalt("sd.chdir");
}
// initMP3Player() sets up all of the initialization for the
// MP3 Player Shield. It runs the begin() function, checks
// for errors, applies a patch if found, and sets the volume/
// stero mode.
void initMP3Player()
{
uint8_t result = MP3player.begin(); // init the mp3 player shield
if(result != 0) // check result, see readme for error codes.
{
// Error checking can go here!
}
MP3player.setVolume(volume, volume);
MP3player.setMonoMode(monoMode);
}
J’ai retiré la première partie que je comprends. Si certains d’entre vous peuvent me venir en aide ça serait avec plaisir. 
Merci.