int8 verificaObstaculo(void)
{
int result_tmp = 0;
int8 result_final = 0;
int result_media = 0;
int8 i = 0;
const int8 n_samples = 5;
result_tmp = 0;
for (i = n_samples; i > 0; i--) {
ADC_START_CONVERSION();
adcWaitConversionFinish();
result_tmp += ADC; //lê os 10 bits do ADC
_delay_us(25); //tempo de cada amostragem utilizando a frequencia do ADC em 1MHz
}
result_media = (result_tmp / n_samples); //faço uma média para evitar falsos positivos
//printf("ADC result:\t%d\n", result_media); //debug
if (result_media > 500) {
result_final = 1;
}
if (result_media <= 500) {
result_final = 0;
}
result_media = 0;
return result_final;
}
/*************************************************************************
Function: ADC_init
Purpose: set up the ADC to be used in IR sensor
**************************************************************************/
void ADC_init(void) {
SENSOR_IR_DDR &= ~_BV(SENSOR_IR_BIT);
//ADC in 10bits : used in IR sensor routine : without shift left or right
ADC_REFERENCE_AREF(); //ADC reference in 5V
ADC_CLOCK_PRESCALER_128();
/* the original ADC frequency of this project was 125KHz (Prescaler = 128), thus, I changed it to sample faster, in 1MHz (Prescaler16)
* I have some loss in precision, working in 10 bits with a frequency bigger than 200KHz, but in this case this do not matters
* */
ADC_ENABLE();
ADC_SELECT_CHANNEL_2();
ADC_DIGITAL_INPUT_2_DISABLE();
ADC_START_CONVERSION(); //I discard the first sample, which takes 25 clock cycles
ADC_WAIT_CONVERSION_FINISH();
}
void init_adc(void)
{
adcs = NULL;
next_adc_to_consider = NULL;
sample_buffer_head = 0;
sample_buffer_count = 2;
uint8_t i;
for (i = 0; i < SAMPLE_BUFFER_SIZE; ++i) {
sample_buffer[i] = NULL;
}
ADC_SET_VREF(AREF);
ADC_SET_ADJUST(RIGHT);
ADC_SET_AUTO_TRIGGER_SRC(ADC_TRIGGER_FREERUNNING);
ADC_AUTO_TRIGGER_ENABLE();
ADC_SET_PRESCALER_DIV(64);
ADC_SET_CHANNEL(ADC_CHANNEL_GND);
ADC_CC_INTERRUPT_ENABLE();
ADC_ENABLE();
ADC_START_CONVERSION();
process_start(&adc_process);
}
int main(void) {
/* Set A7 as an output. (Needed for PWM.) */
DDRA |= _BV(DD7);
PORTA = 0;
/* Let input power stabilize... */
_delay_ms(500);
/*
* Configure Timer0 as a fast PWM. It will
* - turn on the output pin at the start of each cycle
* - turn it off when the value hits DUTY_CYCLE_REG
* - wrap to 0 when it hits OCR0A
*/
TCCR0A = _BV(COM0B1) | _BV(WGM01) | _BV(WGM00);
OCR0A = PWM_RESOLUTION;
/* Start with 40% duty cycle and ramp up to avoid inrush. */
DUTY_CYCLE_REG = (uint8_t)(PWM_RESOLUTION * 0.40);
/* Set Timer0 clock source to be main oscillator. This enables the timer. */
TCCR0B = _BV(CS00) | _BV(WGM02);
/*
* Turn on the ADC,
* - use internal voltage ref.
* - configure ADC0 as our source
* - left-adjust the result, 8-bits is enough for us
* - disable digital input buffer on pin
* - enable the ADC.
*/
ADMUX = /* REF = */ _BV(REFS1) | /* INPUT = */ 0;
ADCSRA |= /* PRESCALER = 16 = 2^ */ 4;
ADCSRB |= /* LEFT-ADJUST */ _BV(ADLAR);
DDRA &= ~_BV(DD0);
DIDR0 |= _BV(ADC0D);
ADC_ENABLE();
_delay_ms(1);
/*
* Now enter our main loop. Monitor the output voltage and manipulate
* the duty cycle to control it.
*/
while (1) {
/* Wait for the Timer0 to overflow... */
loop_until_bit_is_set(TIFR0, TOV0);
/* End of our OFF period, should be peak voltage... */
TIFR0 |= _BV(TOV0); /* Clear the flag. */
/* Check the output voltage. */
ADC_START_CONVERSION();
loop_until_bit_is_clear(ADCSRA, ADSC);
uint8_t adc_result = ADCH;
if (adc_result < DESIRED_ADC_RESULT &&
DUTY_CYCLE_REG < MAX_PWM_LEVEL) {
DUTY_CYCLE_REG++;
}
else if (adc_result > DESIRED_ADC_RESULT &&
DUTY_CYCLE_REG > MIN_PWM_LEVEL) {
DUTY_CYCLE_REG--;
}
}
}
