/*
Code pour lire la data du I2C decibel meter
Pour compiler le code: gcc -o sound_meter sound_meter.c
Connexion I2C: 
SDA to Pi Pico GPIO 2
SCL to Pi Pico GPIO 3

Device connected on addr 0x48

0x0A : Decibel register (Latest sound intensity value in decibels, averaged over the last Tavg time period.)
0x0B : Min register (Minimum value of decibel reading captured since power-up or manual reset of MIN/MAX registers.)
0x0C : Max register (Maximum value of decibel reading captured since power-up or manual reset of MIN/MAX registers.)

#Le Tavg est programmé sur 2 octets: le high byte et le low byte.
 valeur = (Tavg_high x 256) + Tavg_low
 0x07          #Averaging time (high byte) in milliseconds for calculating sound intensity levels. (default 0x03)
 0x08          #Averaging time (low byte) in milliseconds for calculating sound intensity levels. (default 0xE8)


*/

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>

int main()
{
	int file;
	char data;
 
	// Open I2C1 for reading the sound meter module registers
	if ((file = open("/dev/i2c-1", O_RDWR)) < 0)
	{
		perror("Failed to open I2C1!");
		exit(1);
	}
	
	// 0x48 is the decibel meter I2C address
	if (ioctl  (file, I2C_SLAVE, 0x48) < 0)
	{
		perror ("db Meter module is not connected/recognized at I2C addr = 0x48");
		close (file);
		exit (1);
	}
	 
	while (1)
	{
		// Decibel value is stored in register 0x0A
		data = 0x0A;

		//write: send 1 byte from data (memory address pointer) to file
		if (write (file, &data, 1) != 1)
		{
			perror ("Failed to write register 0x0A");
			close (file);
			exit (1);
		}
		 
		if (read (file, &data, 1) != 1)
		{
			perror ("Failed to read register 0x0A");
			close (file);
			exit (1);
		}
		 	 
		printf ("Sound level: %d dB SPL\r\n\r\n", data);
		sleep (1);
	}
	
	close (file);
	return 0;
}