====== Project - Finger counter ======

  * {{examples:projects:finger_counter:finger_counter.zip|AVRStudio full project}}

===== main.c =====

The project uses IR sensor and servo motor for scanning sector.
Putting hands on the front of scanning sector the result should be number of spread out fingers.



<code c>
#include <avr/io.h>
#include <util/delay.h>
#include <stdlib.h>
#include "adc.h"
#include "motors.h"
#include "lcd.h"
#include "segment_display.h"
#include "pinops.h"
#include "configuration.h"

// Math operations
#define DIFF(a, b) ((a) < (b) ? (b) - (a) : (a) - (b))
#define INTEGRATE(value, new_value, n)    value = (value * (n - 1) + new_value) / n;

//
// Main entrance
//
int main(void)
{
	unsigned short distance, compare_distance = 0;
	unsigned char matches = 0, num_fingers = 0;
	signed short servo_pos = -100, scan_dir = 1;
	char text[10];

	// Initialize
	adc_init();
	dcmotors_init();
	segment_display_init();
	servomotors_init();
	setup_output_pin(LED_RED);	

	lcd_init(LCD_DISP_ON);
	lcd_clrscr();
	lcd_puts("Finger counter");

	// Endless loop
	while (1)
	{	
		// Scan
		servomotors_position(1, servo_pos);
		servo_pos += scan_dir;

		// Servo on edge ?
		if ((servo_pos < -100) || (servo_pos > 100))
		{
			scan_dir = (servo_pos > 0 ? -1 : 1);

			// Output results
			segment_display_write(num_fingers);
			itoa(num_fingers, text, 10);
			lcd_gotoxy(0, 1);
			lcd_puts(text);
			lcd_puts("  ");

			// Reset fingers count
			num_fingers = 0;
		}

		// Measure distance
		distance = adc_sample_value(0, 4);		

		// Check for drastic changes
		// Look for decreasing distance (increasing sensor output voltage)
		if (distance > compare_distance + 100)		    
		{
			// Light on finger
			clear_pin(LED_RED); // inverted!

			// Changes has to last for some time
			if (matches++ == 5)
			{				
				// Count fingers
				num_fingers++;			
			}
		}
		else
		{
			// Reset matches and turn off the LED
			set_pin(LED_RED); // inverted!
			matches = 0;			
		}

		// Calculate compare distance (integrated distance) 
		INTEGRATE(compare_distance, distance, 20);

		// Pause
		_delay_ms(10);
	}
}
</code>

===== configuration.h =====

<code c>
// Hardware pin configurations

#define BUTTON_1      PORTPIN(C, 2)
#define BUTTON_2      PORTPIN(C, 1)
#define BUTTON_3      PORTPIN(C, 0)

#define LED_RED       PORTPIN(C, 5)
#define LED_YELLOW    PORTPIN(C, 4)
#define LED_GREEN     PORTPIN(C, 3)

#define DCMOTOR_1A    PORTPIN(B, 7)
#define DCMOTOR_1B    PORTPIN(B, 4)
#define DCMOTOR_2A    PORTPIN(D, 1)
#define DCMOTOR_2B    PORTPIN(D, 0)
#define DCMOTOR_3A    PORTPIN(D, 7)
#define DCMOTOR_3B    PORTPIN(D, 6)
#define DCMOTOR_4A    PORTPIN(D, 5)
#define DCMOTOR_4B    PORTPIN(D, 4)

#define SERVOMOTOR_1  PORTPIN(B, 5)
#define SERVOMOTOR_2  PORTPIN(B, 6)

#define SEGMENT_DISPLAY_LATCH      PORTPIN(G, 2)
#define SEGMENT_DISPLAY_DATA_OUT   PORTPIN(C, 6)
#define SEGMENT_DISPLAY_CLOCK      PORTPIN(C, 7)
</code>

===== adc.c =====

<code c>
#include <avr/io.h>
#include "pinops.h"

//
// ADC initialization
//
void adc_init(void)
{
	// ADC setup
	// Prescaler 8
	ADCSRA = BIT(ADEN) | BIT(ADPS1) | BIT(ADPS0);

	// Reference voltage to external (+5V)
	ADMUX = BIT(REFS0);
}

//
// ADC conversion waiting
//
void adc_wait_until_done(void)
{
	while (IS_BIT_SET(ADCSRA, ADSC))
	{
		asm volatile ("nop");
  	}
}

//
// ADC channel value sampling
//
unsigned short adc_sample_value(unsigned char channel, unsigned char num_samples)
{	
	unsigned short result = 0;

	// Specify channel
	ADMUX &= 0xF0;
	ADMUX |= channel & 0x0F;

	// Take test sample to "warm up" converter
	// Usually the first sample is discarded
	SET_BIT(ADCSRA, ADSC);
	adc_wait_until_done();
	
	// Real sampling, sum up specifed number of samples
	for (unsigned char i = 0; i < num_samples;i++)
	{
		SET_BIT(ADCSRA, ADSC);
		adc_wait_until_done();

		// Sum-up
		result += ADCW;
	}

	// Return averaged result
	return (result / num_samples);	
}
</code>

===== adc.h =====

<code c>
// ADC function headers
void adc_init(void);
unsigned short adc_sample_value(unsigned char channel, unsigned char num_samples);
</code>

===== motors.c =====

<code c>
#include <avr/io.h>
#include "pinops.h"
#include "configuration.h"

// PWM full period
// 14.745600 Mhz / 8 / 50 Hz = 36864
#define PWM_PERIOD      (F_CPU / 8 / 50)

// PWM servo middle position
// 36864 / 20 ms * 1.5 ms = 2764
#define PWM_MIDDLE_POS  (PWM_PERIOD * 15 / 200)

// PWM ratio to get position from -100 to 100
// 36864 / 20 ms / 2 / 100
// We add +1 to get a full range and a little bit more
#define PWM_RATIO       (PWM_PERIOD / 20 / 2 / 100 + 1)

//
// Initialize motors
//
void dcmotors_init(void)
{
	setup_output_pin(DCMOTOR_1A);
	setup_output_pin(DCMOTOR_1B);
	setup_output_pin(DCMOTOR_2A);
	setup_output_pin(DCMOTOR_2B);
	setup_output_pin(DCMOTOR_3A);
	setup_output_pin(DCMOTOR_3B);
	setup_output_pin(DCMOTOR_4A);
	setup_output_pin(DCMOTOR_4B);
}

//
// Drive command for specified motor
//
void dcmotors_drive(unsigned char nr, signed char dir)
{
	switch (nr)
	{
		case 1:
			set_pin_to(DCMOTOR_1A, dir < 0);			
			set_pin_to(DCMOTOR_1B, dir > 0);
			break;

		case 2:
			set_pin_to(DCMOTOR_2A, dir < 0);			
			set_pin_to(DCMOTOR_2B, dir > 0);
			break;

		case 3:
			set_pin_to(DCMOTOR_3A, dir < 0);			
			set_pin_to(DCMOTOR_3B, dir > 0);
			break;

		case 4:
			set_pin_to(DCMOTOR_4A, dir < 0);			
			set_pin_to(DCMOTOR_4B, dir > 0);
			break;
	}
}

//
// Intialize servo motors
//
void servomotors_init(void)
{
	setup_output_pin(SERVOMOTOR_1);

	setup_output_pin(SERVOMOTOR_2);

	// Set timer control registers
	// Clear OUTA and OUTB on compare match
	// Fast PWM mode with ICR = TOP
	// Prescaler 8
	TCCR1A = BIT(COM1A1) | BIT(COM1B1) | BIT(WGM11);
	TCCR1B = BIT(CS11) | BIT(WGM13) | BIT(WGM12); 

	// TOP period	
	ICR1 = PWM_PERIOD;
}

//
// Position servo motors
// pos is from -100 to 100
//
void servomotors_position(unsigned char nr, signed short pos)
{
	// 
	switch (nr)
	{
		case 1: OCR1A = PWM_MIDDLE_POS + pos * PWM_RATIO; break;
		case 2: OCR1B = PWM_MIDDLE_POS + pos * PWM_RATIO; break;
	}
}
</code>

===== motors.h =====

<code c>
// Motor function headers
void dcmotors_init(void);
void dcmotors_drive(unsigned char nr, signed char dir);
void servomotors_init(void);
void servomotors_position(unsigned char nr, signed short pos);
</code>

===== segment_display.c =====

<code c>
#include <avr/io.h>
#include <util/delay.h>
#include "pinops.h"
#include "configuration.h"

//
// 7 segment display initialization
//
void segment_display_init(void)
{
	// Set latch, data out and clock pins as output
	setup_output_pin(SEGMENT_DISPLAY_LATCH);
	setup_output_pin(SEGMENT_DISPLAY_DATA_OUT);
	setup_output_pin(SEGMENT_DISPLAY_CLOCK);	
}
 
//
// Digit writing to 7 segment display
//
void segment_display_write(unsigned char digit)
{
	unsigned char map;
 
	// Decimal to segment map
	switch (digit)
	{
		case 0 : map = 0b00111111; break; // Every bit corresponds to one segment
		case 1 : map = 0b00000110; break; // "1"
		case 2 : map = 0b01011011; break; // "2"
		case 3 : map = 0b01001111; break; // "3" and so on
		case 4 : map = 0b01100110; break; 
		case 5 : map = 0b01101101; break; 
		case 6 : map = 0b01111100; break; 
		case 7 : map = 0b00000111; break;
		case 8 : map = 0b01111111; break; 
		case 9 : map = 0b01100111; break;  
		default: map = 0b01111001;        // E like Error
	}	
 
	// Latch low
	clear_pin(SEGMENT_DISPLAY_LATCH);
 
	// Send every bit in the byte. MSB (most significant bit) first.
	for (signed char i = 7; i >= 0; i--)
	{
		// If bit is set, sets the data out pin, otherwise not		
		set_pin_to(SEGMENT_DISPLAY_DATA_OUT, IS_BIT_SET(map, i));
 
		// Clock high for certain period
		set_pin(SEGMENT_DISPLAY_CLOCK)
		_delay_us(1);
 
		// Clock low for certain period		
		clear_pin(SEGMENT_DISPLAY_CLOCK)
		_delay_us(1);
	}
 
	// Latch high 	
	set_pin(SEGMENT_DISPLAY_LATCH);
}
</code>

===== segment_display.h =====

<code c>
// 7 segment display function headers
void segment_display_init(void);
void segment_display_write(unsigned char digit);
</code>