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sound_meter/sound_meter.c

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+/*
+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
+
+to start the script:
+sudo /var/www/nebuleair_pro_4g/sound_meter/sound_meter
+
+0x00 : 	VERSION register
+0x01 :  Device ID (byte 1)
+0x02 : 	Device ID
+0x03 : 	Device ID
+0x04 : 	Device ID (byte 4)
+0x05 : 	SKRATCH register
+0x06 : 	CONTROL register
+0x07 : 	TAVG high register
+0x08 : 	TAVG low register
+0x09 : 	RESET register
+
+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.
+ 0x07          #Averaging time (high byte) in milliseconds for calculating sound intensity levels. (default 0x03 -> 3)
+ 0x08          #Averaging time (low byte) in milliseconds for calculating sound intensity levels. (default 0xE8 -> 232)
+ valeur = (Tavg_high x 256) + Tavg_low
+		= (3 * 256) + 232
+		= 1000 ms 
+		= 1 s
+
+*/
+
+#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);
+	}
+	
+	// Decibel value is stored in register 0x0A
+	data = 0x0A;
+
+	// Write the register address (0x0A) to the device
+	if (write(file, &data, 1) != 1)
+	{
+		perror("Failed to write register 0x0A");
+		close(file);
+		exit(1);
+	}
+
+	// Read one byte from the device
+	if (read(file, &data, 1) != 1)
+	{
+		perror("Failed to read register 0x0A");
+		close(file);
+		exit(1);
+	}
+
+	// Display the sound level
+	printf("%d\n", data);
+
+	// Close the I2C connection
+	close(file);
+	return 0;
+}