Sensors

Related to: [HW] Sensors Module

This library contains functions to use different sensors in Homelab kit.

• 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.

• ir_distance_sensor GP2Y0A21YK
  

Sharp GP2Y0A21YK distance calculation formula parameters.

• 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(pin trigger, pin echo)
  

Measures distance with ultrasonic distance sensor. Functions generate 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.

The following program demonstrates usage of IR and ultrasonic distance sensors.

#include <homelab/module/sensors.h>
 
// Ultrasonic distance sensor control pins.
pin pin_trigger = PIN(G, 1);
pin pin_echo    = 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(pin_trigger, pin_echo);
}