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/* 
Program Description: This program reads a light detecting resistor thru an internal ADC and stores the value,  
after scaling it, to eeprom.  This ADC value is sent to a PWM channel with attached led.  This is essentially a data logger 
for light and replay by LED.  If, if you aim the LDR at a flickering candle during its recording phase, you have a flickering  
led candle.   
A circuit description and other details can be found at https://petemills.blogspot.com 
Filename: ATTiny_Candle_v1.0.c 
Author: Pete Mills 
Int. RC Osc. 8 MHz; Start-up time PWRDWN/RESET: 6 CK/14 CK + 64 ms 
*/  
//********** Includes **********  
#include        
#include      
#include   
//********** Definitions **********  
// LED for flame simulation  
#define LED   PB0    
#define LED_PORT PORTB  
#define LED_DDR  DDRB  
// Light Detecting Resistor for recording a live flame  
#define LDR   PINB3   
#define LDR_PORT PINB  
#define LDR_DDR  DDRB  
// Tactile Switch Input  
#define SW1   PINB4  
#define SW1_PORT PINB  
#define SW1_DDR  DDRB  
#define ARRAY_SIZE 500  // size of the flicker array  
#define SAMPLE_RATE 100  // ms delay for collecting and reproducing the flicker  
//********** Function Prototypes **********  
void setup(void);  
void toggle_led(void);  
void program_flicker(void);  
void led_alert(void);  
void eeprom_save_array(void);  
void eeprom_read_array(void);  
void scale_array(void);  
uint8_t get_adc(void);  
uint8_t scale( uint8_t input, uint8_t inp_low, uint8_t inp_hi, uint8_t outp_low, uint8_t outp_hi);  
uint8_t is_input_low(char port, char channel, uint8_t debounce_time, int input_block);  
//********** Global Variables **********  
uint8_t flicker_array[ ARRAY_SIZE ] = { 0 };  
uint8_t EEMEM ee_flicker_array[ ARRAY_SIZE ] = { 0 };  
int main(void)  
{  
uint16_t replay = 0;  
setup();  
eeprom_read_array();  
 while(1)  
 {   
  if( is_input_low( SW1_PORT, SW1, 25, 250 ) )  
  {  
   // program the flicker  
   // after entering and upon completion, a predetermined flash pattern will occur as described in led_alert()    
   // aim the ldr at a flickering candle or any other light source ( like a laser ) you want to record during this time  
   // and upon completion the values are stored to eeprom.  They are played back immediately as well   
   // as being recalled from eeprom upon first start up  
   led_alert();  
   program_flicker();  
   scale_array();  
   eeprom_save_array();  
   led_alert();  
  }  
  // replay the recorded flicker pattern   
  OCR0A = flicker_array[ replay ];  
  ++replay;  
  if( replay >= ( ARRAY_SIZE - 13 ) ) // if the end of the stored array has been reached  
  {   
   replay = 0;          // start again from the beginning  
   //led_alert();  
  }  
  _delay_ms( SAMPLE_RATE );  
  _delay_ms( 3 );    // ADC Conversion time  
 }  
}  
//********** Functions **********  
void setup(void)  
{  
 //********* Port Config *********  
 LED_DDR |= ( 1 << LED);   // set PB0 to "1" for output   
 LED_PORT &= ~( 1 << LED );   // turn the led off  
 LDR_DDR &= ~( 1 << LDR );   // set LDR pin to 0 for input  
 LDR_PORT |= ( 1 << LDR );   // write 1 to enable internal pullup  
 SW1_DDR &= ~( 1 << SW1 );   // set sw1 pin to 0 for input  
 SW1_PORT |= ( 1 << SW1 );   // write a 1 to sw1 to enable the internal pullup  
 //********** PWM Config *********  
 TCCR0A |= ( ( 1 << COM0A1 ) | ( 1 << WGM01 ) | ( 1 << WGM00 ) ); // non inverting fast pwm  
 TCCR0B |= ( 1 << CS00 ); // start the timer  
 //********** ADC Config **********  
 ADMUX |= ( ( 1 << ADLAR ) | ( 1 << MUX1 ) | ( 1 << MUX0 ) );  // left adjust and select ADC3  
 ADCSRA |= ( ( 1 << ADEN ) | ( 1 << ADPS2 ) | ( 1 << ADPS1 ) ); // ADC enable and clock divide 8MHz by 64 for 125khz sample rate  
 DIDR0 |= ( 1 << ADC3D ); // disable digital input on analog input channel to conserve power  
}  
void toggle_led()  
{  
    LED_PORT ^= ( 1 << LED );  
}  
uint8_t is_input_low( char port, char channel, uint8_t debounce_time, int input_block )  
{  
/*  
This function is for debouncing a switch input  
Debounce time is a blocking interval to wait until the input is tested again.  
If the input tests low again, a delay equal to input_block is executed and the function returns ( 1 )  
*/  
 if ( bit_is_clear( port, channel ) )  
 {  
  _delay_ms( debounce_time );  
   if ( bit_is_clear( port, channel ) )   
   {  
    _delay_ms( input_block );  
    return 1;  
   }  
 }  
 return 0;  
}  
uint8_t get_adc()  
{  
 ADCSRA |= ( 1 << ADSC );   // start the ADC Conversion  
 while( ADCSRA & ( 1 << ADSC ));  // wait for the conversion to be complete  
 return ~ADCH; // return the inverted 8-bit left adjusted adc val  
}  
void program_flicker()  
{   
 // build the flicker array  
 for( int i = 0; i < ARRAY_SIZE; i++ )  
 {  
  flicker_array[ i ] = get_adc();    
  _delay_ms( SAMPLE_RATE );  
 }  
}  
void led_alert()  
{  
 // this is a function to create a visual alert that an event has occured within the program  
 // it toggles the led 10 times.  
 for( int i = 0; i < 10; i++ )  
 {  
  OCR0A = 0;  
  _delay_ms( 40 );  
  OCR0A = 255;  
  _delay_ms( 40 );  
 }  
}  
void eeprom_save_array()  
{   
 for( int i = 0; i < ARRAY_SIZE; i++ )  
 {  
  eeprom_write_byte( &ee_flicker_array[ i ], flicker_array[ i ] );  
 }  
}  
void eeprom_read_array()  
{  
 for( int i = 0; i < ARRAY_SIZE; i++ )  
 {  
  flicker_array[ i ] = eeprom_read_byte( &ee_flicker_array[ i ] );  
 }  
}  
uint8_t scale( uint8_t input, uint8_t inp_low, uint8_t inp_hi, uint8_t outp_low, uint8_t outp_hi)  
{  
return ( ( ( input - inp_low ) * ( outp_hi - outp_low ) ) / ( ( inp_hi - inp_low ) + outp_low ) );  
}  
void scale_array()  
{  
 uint8_t arr_min = 255;  
 uint8_t arr_max = 0;  
 uint8_t out_low = 20;  
 uint8_t out_high = 255;  
 // find the min and max values  
 for( int i = 0; i < ARRAY_SIZE; i++ )  
 {  
  if( flicker_array[ i ] < arr_min )  
   arr_min = flicker_array[ i ];  
  if( flicker_array[ i ] > arr_max )  
   arr_max = flicker_array[ i ];  
 }  
 // now that we know the range, scale it  
 for( int i = 0; i < ARRAY_SIZE; i++ )  
 {  
  flicker_array[ i ] = scale( flicker_array[ i ], arr_min, arr_max, out_low, out_high );  
 }  
}   igh );  
 }  
}   igh );  
 }  
}    
 }  
}    
 }  
}    
 }  
}    }  
}    }  
}    }  
}