// Demo application to read analog input voltage 0 on the BeagleBone
// Assumes ADC cape already loaded by uBoot:

#include <stdlib.h>
#include <stdbool.h>
#include <stdio.h>

#define A2D_FILE_VOLTAGE0  "/sys/bus/iio/devices/iio:device0/in_voltage0_raw"
#define A2D_VOLTAGE_REF_V  1.8
#define A2D_MAX_READING    4095

int getVoltage0Reading()
{
	// Open file
	FILE *f = fopen(A2D_FILE_VOLTAGE0, "r");
	if (!f) {
		printf("ERROR: Unable to open voltage input file. Cape loaded?\n");
		printf("       Check /boot/uEnv.txt for correct options.\n");
		exit(-1);
	}

	// Get reading
	int a2dReading = 0;
	int itemsRead = fscanf(f, "%d", &a2dReading);
	if (itemsRead <= 0) {
		printf("ERROR: Unable to read values from voltage input file.\n");
		exit(-1);
	}

	// Close file
	fclose(f);

	return a2dReading;
}

int main()
{
	while (true) {
		int reading = getVoltage0Reading();
		double voltage = ((double)reading / A2D_MAX_READING) * A2D_VOLTAGE_REF_V;
		printf("Value %5d ==> %5.2fV\n", reading, voltage);
	}
	return 0;
}