Conversor Analógico para Digital

Esta biblioteca fornece funções para usar o conversor analógico para digital do AVR. Todas as funções desta biblioteca bloqueiam o processador até chegarem ao resultado. O tempo de conversão depende do relógio ADC.

• adc_reference
  Enumeração dos tipos para voltagem de referência do ADC. Opções:

• ADC_REF_AREF - Voltagem de referência do pin AREF.
• ADC_REF_AVCC - Voltagem de referência do pin AVCC.
• ADC_REF_2V56 - Voltagem de referência interna - 2,56 V.

• adc_prescale
  ADC clock prescaler enumration data type. It determines the division factor of system clock. Options:
  • ADC_PRESCALE_2 - Division factor 2.
  • ADC_PRESCALE_4 - Division factor 4.
  • ADC_PRESCALE_8 - Division factor 8.
  • ADC_PRESCALE_16 - Division factor 16.
  • ADC_PRESCALE_32 - Division factor 32.
  • ADC_PRESCALE_64 - Division factor 64.
  • ADC_PRESCALE_128 - Division factor 128.

• void adc_init(adc_reference reference, adc_prescale prescale)
  

Initializes ADC. Parameters:

• reference - Reference voltage selection.
• prescale - Clock prescaler selection.

• unsigned short adc_get_value(unsigned char channel)
  

Converts specified ADC channel analog value to digital. Function is blocking. Parameter:

• channel - ADC channel number (0 to 7).
• Return 10-bit digital value.

• unsigned short adc_get_average_value(unsigned char channel, unsigned char num_samples)
  

Converts specified ADC channel analog value to digital desired number of times and calculates the average. Function is blocking. Parameters:

• channel - ADC channel number (0 to 7).
• num_samples - Number of samples for calculation (1 to 64).
• Return 10-bit digital value.

For example ADC is initialized and two analog channel values are converted to digital. Value of channel 0 is assigned to variable x and averaged value of channel 1 to variable y.

#include <homelab/adc.h>
 
int main(void)
{
	unsigned short x, y;
 
	// Initializing ADC. Reference voltage from AVCC.
	// Clock is 8 times slower than system clock.
	adc_init(ADC_REF_AVCC, ADC_PRESCALE_8);
 
	// Converting channel 0 value.
	x = adc_get_value(0);
 
	// Converting and averaging channel 1 value.
	y = adc_get_average_value(1, 10);
}