//DFPlayer Mini ATtiny13A 20240614 1600

/*
  https://www.youtube.com/watch?v=UO_GZ-zX3-k

                          ATtiny85         5VCC        DFPlayerMini
   +-- VUP -- R47k --+  +----------+        |         +-------------+
   |-- VDN -- R10k --+  | RST  VCC |--------+---------|  VCC        |
   |-- RPT ----------+--| PB3  PB2 |-- R1K -----------|  RXD        |
   |-- NXT -------------| PB4  PB1 |------------------|  TXD        |
   |                 +--| GND  PB0 |-- PRV --+   +----|  SP1 ADKEY1 |-- R33k -- PLP --+
   |                 |  +----------+         |   | +--|  SK2    GND |--+              |
   |                 |                       |   | |  +-------------+  |              |
  GND               GND                     GND  SPK                  GND            GND

*/

#include <avr/io.h>
#define F_CPU 9600000UL
#include <util/delay.h>
#include <avr/interrupt.h>
#include <avr/eeprom.h>

uint8_t i, k, ct, total, dat, res[10], rpt;
int8_t vol, num;
uint16_t va;

void eep_write(uint8_t ads, uint8_t dat) {  //EEPROM Write

  while (EECR & (1 << EEPE))
    ;                                  //Wait
  EECR = (0 << EEPM1) | (0 << EEPM0);  //Programing Mode
  EEAR = ads;                          //Address
  EEDR = dat;                          //Data
  EECR |= (1 << EEMPE);                //Enable
  EECR |= (1 << EEPE);                 //Start
  _delay_ms(150);
}

void eep_read(uint8_t ads) {  //EEPROM Read

  while (EECR & (1 << EEPE))
    ;                   //Wait
  EEAR = ads;           //Address
  EECR |= (1 << EERE);  //Read
  dat = EEDR;           //Data
}

void tx(uint8_t com, uint8_t dat) {  //UART TX

  uint8_t t[] = { 0x7E, 0xFF, 0x06, com, 0x00, 0x00, dat, 0xEF };
  _delay_ms(20);
  for (k = 0; k < 8; k++) {
    PORTB &= ~(1 << 2);
    _delay_us(104);  //Start
    for (i = 0; i < 8; i++) {
      if ((t[k] >> i) & 1) {
        PORTB |= (1 << 2);
      } else {
        PORTB &= ~(1 << 2);
      }
      _delay_us(98);
    }
    PORTB |= (1 << 2);
    _delay_us(104);  //Stop
  }
}

ISR(PCINT0_vect) {  //UART RX

  for (k = 0; k < 10; k++) {
    ct = 0;
    while (PINB & 0x02) {
      ct++;
      _delay_us(1);
      if (ct > 250) { break; }
    }
    _delay_us(156);
    for (i = 0; i < 8; i++) {
      res[k] >>= 1;
      if (PINB & 0x02) { res[k] |= (1 << 7); }
      _delay_us(98);
    }
  }

  if (res[3] == 0x48) { total = res[6]; }  //Total Number

  if (res[3] == 0x3D) {  //Next Music
    if (!rpt) { num++; }
    if (num > total) { num = 1; }
    tx(0x03, num);
    eep_write(0x00, num);
  }
}

void music() {
  tx(0x03, num);
  eep_write(0x00, num);
}

void volume() {
  tx(0x06, vol);
  eep_write(0x02, vol);
}

int main(void) {

  CLKPR = 0b10000000;  //Prescaler Change Enable
  CLKPR = 0b00000000;  //Div1(9.6MHz)

  DDRB = 0b00000100;
  PORTB = 0b00011101;  //PB4:Next ,PB3:Volume, PB2:TX, PB1:RX, PB0:Previous

  GIMSK = 0b00100000;  //PCINT Enable
  PCMSK = 0b00000010;  //PCINT1

  ADMUX = 0b00000011;   //Reference:VCC, ADC3 Enable
  ADCSRA = 0b10000000;  //ADC Eable, CK/2
  DIDR0 = 0b00001000;   //Digtal Input Disable(ADC3)
  sei();

  _delay_ms(1500);

  tx(0x48, 0);  //Query Total Number

  eep_read(0x02);  //Read Volume
  vol = dat;
  if (vol > 30 || vol < 0) { vol = 10; }
  tx(0x06, vol);  //Volume

  eep_read(0x00);  //Read Music Number
  num = dat;
  if (num > total) { num = 1; }
  tx(0x03, num);  //Play
  eep_write(0x00, num);

  //-------------------------------------
  while (1) {

    ADCSRA |= 0b01000000;
    while (ADCSRA & 0b01000000)
      ;
    va = ADC;

    if (va > 490 && va < 590) {  //Volume Up
      vol++;
      if (vol > 30) { vol = 30; }
      volume();
    }

    if (va > 170 && va < 270) {  //Volume Down
      vol--;
      if (vol < 0) { vol = 0; }
      volume();
    }

    if (va < 100) {  //Repeat
      rpt ^= 1;
      _delay_ms(1000);
    }

    if (~PINB & 0x01) {  //PB0:Previous
      num--;
      if (num < 1) { num = total; }
      music();
      while (~PINB & 0x01) {}
      _delay_ms(27);
    }

    if (~PINB & 0x10) {  //PB4:Next
      num++;
      if (num > total) { num = 1; }
      music();
      while (~PINB & 0x10) {}
      _delay_ms(27);
    }
  }
}