Random Generator for MP3 player

Projects General Guidance
1

Okay first off I'm a nut for Halloween and this is a project for a decoration. I have found a great many prop controller on line and some using a UNO.
One controller has ambient sound playing until the PIR is triggered and then there is a Scare sound file that plays.
I'm wondering if I get a servo to animated a Skeleton mouth, can the sketch code have a line that randomly selects a file between a set of number? Say file 1 to file 20, and each file would be just called a number so that way the audio file could be changed without having to change the code.

Thanks in advance!

Tim

2

Yes, sure.

3

this initializes a YX-5300 module and plays one of the 15 files in folder 0 at random upon startup:

  delay(500);//Wait until chip initialization is complete
  sendCommand(CMD_SEL_DEV, DEV_TF);                     //select the YX5300 TF card 
  //delay(200);//wait for 200ms
  sendCommand(CMD_SET_VOLUME, 0x06001e);
  randomSeed(analogRead(A0));      
  sendCommand(CMD_PLAY_W_INDEX, 0X030000 +random(1,15));// play on reset 1 of 15 files in root folder

it uses this function:

void sendCommand(uint8_t command, int16_t dat)
{
  Send_buf[0] = 0x7e;    //starting byte
  Send_buf[1] = 0xff;    //version
  Send_buf[2] = 0x06   ; //the number of bytes of the command without starting byte and ending byte
  Send_buf[3] = command; //
  Send_buf[4] = 0x00;    //0x00 = no feedback, 0x01 = feedback
  Send_buf[5] = (int8_t)(dat >> 8);//data high byte
  Send_buf[6] = (int8_t)(dat); //data low byte
  Send_buf[7] = 0xef; //ending byte
  
  for(uint8_t i=0; i<8; i++)//
  {
   Serial2.write(Send_buf[i]);
   lcd4.setCursor(6,3); lcd4.print("  "); lcd4.setCursor(6,3); lcd4.print(dat >> 8, HEX);
   lcd4.setCursor(8,3); lcd4.print("  "); lcd4.setCursor(8,3); lcd4.print(dat & 15, HEX);
  }
}

it requires this on top, below the libraries:

//  YX-5300
#define CMD_SEL_DEV 0X09
#define DEV_TF 0X02
#define CMD_SET_VOLUME 0X06
#define CMD_PLAY_W_INDEX 0X03

static unsigned int Send_buf[8] = {0};  // char string for YX-5300 commands

you can use up to 256 folders, 256 files per folder, with this module

4

Please see this thread. It should have exactly what you're looking for, minus the servo control

5

Isn't it easier to just use the DF Player Mini library for this?

6

One way to get randoms is to use low order bits from millis().

The millis() function returns ms since startup as a 32 bit value but if you assign it to a byte then the low 8 bits is what you get.

byte rando;

......

rando = millis(); // pseudo-random 0-255

If you want 0 to 15 then

rando = rando & 15; // 15 is binary 00001111