// CS-33301 Project #4 Question 1
// by Chase Osborne
// With code from Prof.JungYoon


// GPIO Variable Initialization
unsigned char *portDDRC;
unsigned char *portPinC;
unsigned char *portC;
unsigned char *portDDRD;
unsigned char *portPinD;
unsigned char *portD;

// ADC Variable Initialization
#define ADC_PIN  0b1110

unsigned char *ADMUX_ESP;
unsigned char *ADCSRA_ESP;
unsigned char *ADCSRB_ESP;
unsigned char *ADCL_ESP;
unsigned char *ADCH_ESP;

// Timer Variable Initializaiton
unsigned char *TCCR1A_ESP;
unsigned char *TCCR1B_ESP;
unsigned char *TCNT1H_ESP;
unsigned char *TCNT1L_ESP;
unsigned char *OCR1AH_ESP;
unsigned char *OCR1AL_ESP;
unsigned char *TIMSK1_ESP;

bool ledON = true; // For LED blink
/*
// External Interrupt Control Initialization
#define EICRA_MASK 0x69
#define EIMSK_MASK 0x3D

unsigned char *AT328_EICRA;
unsigned char *AT328_EIMSK;
unsigned char *ptrSREG;
*/

bool beenRead = false; // for temperature reading

// Dr.JungYoon's adc_read function
uint16_t adc_read(uint8_t adcx);

void setup(){
  Serial.begin(9600); // open the serial port at 9600 bps:

  // ADC assignment
  ADMUX_ESP = (unsigned char*) 0x7c;
  ADCSRA_ESP = (unsigned char*) 0x7a;
  ADCSRB_ESP = (unsigned char*) 0x7b;
  ADCL_ESP = (unsigned char*) 0x78;
  ADCH_ESP = (unsigned char*) 0x79;

  *ADCSRA_ESP |= 0b10000000; // Enabling ADC

  // GPIO Assignment
  portDDRC = (unsigned char*) 0x27;
  portPinC = (unsigned char*) 0x26;
  portC    = (unsigned char*) 0x28;
  portDDRD = (unsigned char*) 0x2A;
  portPinD = (unsigned char*) 0x29;
  portD    = (unsigned char*) 0x2B; 

  *portDDRD &= 0b11111011;  // Configure bit 0 as input
  *portDDRC |= 0b00000010;  // Configure bit 5 as an output
  *portC    &= 0b11111101; // Default to off

  // Timer Assignment
  TCCR1A_ESP = (unsigned char *) 0x80;
  TCCR1B_ESP = (unsigned char *) 0x81;
  TCNT1H_ESP = (unsigned char *) 0x85;
  TCNT1L_ESP = (unsigned char *) 0x84;
  OCR1AH_ESP = (unsigned char *) 0x89;
  OCR1AL_ESP = (unsigned char *) 0x88;
  TIMSK1_ESP = (unsigned char *) 0x6F;

  *TCCR1A_ESP = 0x00;
  *TCCR1B_ESP = 0x0C; // CTC mode - BIT 3; 256 prescaler BIT2
  *TCNT1H_ESP = 0x00;
  *TCNT1L_ESP = 0x00;

  *OCR1AH_ESP = 0xF4; // OCRA value of 62499 for 1hz updates 
  *OCR1AL_ESP = 0x23;

  *TIMSK1_ESP = 0x02; // enable timer compare interrupt - BIT1
  /*
  // Interrupt Assignment
  AT328_EICRA = (unsigned char *) EICRA_MASK;
  AT328_EIMSK = (unsigned char *) EIMSK_MASK;

  // Enabling Interrupt on any logical change of INT0/PB0/D8
  *AT328_EICRA |= 0b00000011; 
  *AT328_EICRA &= 0b11111100;
  *AT328_EIMSK |= 0b00000001;

  // SREG Assignment
  portDDRD = (unsigned char *) 0x5F;
  *portDDRD |= 0x80;
  */
}

void loop() {
  if (beenRead == false) {
    if ((*portPinD) &= 0b00000100) {
      Serial.print("[email protected]:");
      Serial.println(adc_read(ADC_PIN));
      beenRead = true;
    }
  }
  if (adc_read(ADC_PIN) >= 270) { ledON = false; }
}
/*
ISR(INT0_vect) {
  Serial.println(BIN, (*portD));
  if ((*portD) &= 0b00000100) {
    Serial.print("[email protected]:");
    Serial.println(adc_read(ADC_PIN));
  }
}
*/
ISR(TIMER1_COMPA_vect){
  if (ledON) {
    ledON = false;
    (*portC) |= 0b00000010; // Turning LED on
  }
  else {
    ledON = true;
    (*portC) &= 0b11111101; // Turning LED off
  }
  // Cooldown for button press
  // Pressing button interrupts LED
  if ((*portPinD) <= 3) {
    beenRead = false;
  }
}

uint16_t adc_read(uint8_t adcx) {
/* adcx is the analog pin we want to use. ADMUX's first few bits are
* the binary representations of the numbers of the pins so we can
* just 'OR' the pin's number with ADMUX to select that pin.
* We first zero the four bits by setting ADMUX equal to its higher
* four bits. */
*ADMUX_ESP &= 0xf0;
*ADMUX_ESP |= adcx;
/* This starts the conversion. */
*ADCSRA_ESP |= 0b01000000;
/* Finally, we return the converted value to the calling function. */
unsigned char cl = *ADCL_ESP;
unsigned char ch = *ADCH_ESP;
return (cl | (ch << 8));
}