====== Sensors ======

//Related to: [HW] [[en:hardware:homelab:sensor]]//

This library contains functions to use different sensors in the HomeLab kit.

===== Data Types =====

  * **//ir_distance_sensor//** \\
    Infrared distance sensor distance calculation parameters structure. Formula for distance calculation is //a / (ADC + b) - k//. Structure members:
    * //a// - Dividend.
    * //b// - Non-linear constant.
    * //k// - Linearizing constant.

===== Constants =====

    * **//ir_distance_sensor GP2Y0A21YK//** \\
    Sharp GP2Y0A21YK distance calculation formula parameters.

===== Functions =====

  * **//signed short thermistor_calculate_celsius(unsigned short adc_value)//** \\
    Calculates thermistor temperature in Celsius degrees from ADC conversion result. Functions use pre-calculated conversion table. Parameters:
    * //adc_value// - ADC conversion result (10-bit with +5 V reference voltage)..
    * Returns temperature in Celsius degrees in the -20 to 100 degrees limit.

  * **//signed short ir_distance_calculate_cm(ir_distance_sensor sensor, unsigned short adc_value)//** \\
    Calculates distance from ADC result received from IR distance sensor voltage. Parameters:
    * //sensor// - Distance sensor calculation parameters.
    * //adc_value// - ADC conversion result (10-bit with +5 V reference voltage).
    * Returns distance in centimeters or -1 if it cannot be calculated.

  * **//unsigned short ultrasonic_measure_srf04(pin trigger, pin echo)//** \\
    Measures distance with ultrasonic distance sensor SRF04. Function generates a trigger pulse on one pin and measures the time of echo pulse on another pin. Distance is calculated from the time. Function expects a 14.7456 MHz clock frequency. Measuring may take up to 36 ms. Parameters:
    * //trigger// - Trigger pin variable.
    * //echo// - Echo pin variable.
    * Returns distance in centimeters or 0 when measuring failed.
  * **//unsigned short ultrasonic_measure_srf05(pin trigger_echo)//** \\
    Measures distance with ultrasonic distance sensor SRF05 in one wire regime. Function generates a trigger pulse on the pin and measures the time of echo pulse on the same pin. Distance is calculated from the time. Function expects a 14.7456 MHz clock frequency. Measuring may take up to 36 ms. Parameters:
    * //trigger_echo// - Trigger/Echo combined pin variable.
    * Returns distance in centimeters or 0 when measuring failed.

===== Example =====

The following program demonstrates usage of IR and ultrasonic distance sensor SRF05.

<code c>
#include <homelab/module/sensors.h>

// Ultrasonic distance sensor control pins.
pin pin_triggerecho    = PIN(G, 0);

int main(void)
{
	unsigned short adc_value = 400; // random ADC result.
	signed short distance;

	// Distance calculation from IR distance sensor ADC result.
	distance = ir_distance_calculate_cm(GP2Y0A21YK, adc_value);

	// Measuring with ultrasonic distance sensor.
	distance = ultrasonic_measure_srf05(pin_triggerecho);
}
</code>