Bonsoir, voici mon schéma : 
et le code :
#include <SD.h>
#include <Wire.h>
#include <SPI.h>
#include "RTClib.h"
#include "Statistic.h"
// A simple data logger for the Arduino analog pins
// how many milliseconds between grabbing data and logging it. 1000 ms is once a second
#define LOG_INTERVAL 5000// mills between entries (reduce to take more/faster data)
#define ECHO_TO_SERIAL 1 // echo data to serial port
// The analog pins that connect to the sensors
const int analogInPinBat = A0; // Analog pin the battery voltage divider is attached to
const int analogInPinPanNeg = A1; //Analog pin the panel negative to ground voltage divider is attached to
//const int analogInPinPanPos = A2; //Analog pin the panel positive to ground voltage divider is attached to
//Ground is provided by the negative battery
const float Vcc = 4.91; // µC Vcc (V)
/*Voltage divider positive panel (Ohm)
const float R1 = 37000;
const float R2 = 13000; */
//Voltage divider negative panel (Ohm)
const float R3 = 37000;
const float R4 = 13000;
//Voltage divider battery (Ohm)
const float R5 = 27000;
const float R6 = 13000;
// the digital pins that connect to the LEDs
#define redLEDpin 2
#define greenLEDpin 3
RTC_DS1307 RTC; // define the Real Time Clock object
// for the data logging shield, we use digital pin 10 for the SD cs line
const int chipSelect = 10;
// the logging file
File logfile;
//the statistics
Statistic PanStats;
Statistic BatStats;
void error(char *str)
{
Serial.print("Erreur: ");
Serial.println(str);
// red LED indicates error
digitalWrite(redLEDpin, HIGH);
while(1);
}
void setup(void)
{
Serial.begin(9600);
Serial.println();
PanStats.clear(); //explicitly start clean
BatStats.clear();
// use debugging LEDs
pinMode(redLEDpin, OUTPUT);
pinMode(greenLEDpin, OUTPUT);
/*#if WAIT_TO_START
Serial.println("Type any character to start");
while (!Serial.available());
#endif //WAIT_TO_START
*/
// initialize the SD card
Serial.print("Initializing SD card...");
// make sure that the default chip select pin is set to
// output, even if you don't use it:
pinMode(10, OUTPUT);
// see if the card is present and can be initialized:
if (!SD.begin(chipSelect)) {
error("Card failed, or not present");
}
Serial.println("card initialized.");
//create a new file
char filename[] = "BATPAN00.CSV";
logfile = SD.open(filename, FILE_WRITE);
if (! logfile) {
error("couldnt create file");
}
Serial.print("Logging to: ");
Serial.println(filename);
// connect to RTC
Wire.begin();
if (!RTC.begin()) {
logfile.println("RTC failed");
#if ECHO_TO_SERIAL
Serial.println("RTC failed");
#endif //ECHO_TO_SERIAL
}
logfile.println("millis; date; VPan; VBAt");
logfile.println();
#if ECHO_TO_SERIAL
Serial.println("millis; date; VPan; VBAt");
Serial.println();
#endif //ECHO_TO_SERIAL
// If you want to set the aref to something other than 5v
//analogReference(EXTERNAL);
}
void loop(void)
{
DateTime now;
// delay for the amount of time we want between readings
delay((LOG_INTERVAL -1) - (millis() % LOG_INTERVAL));
digitalWrite(greenLEDpin, HIGH);
// log milliseconds since starting
uint32_t m = millis();
#if ECHO_TO_SERIAL
Serial.print(m); // milliseconds since start
Serial.print("; ");
#endif
// fetch the time
now = RTC.now();
// log time in serial console
#if ECHO_TO_SERIAL
Serial.print(now.day(), DEC);
Serial.print("/");
Serial.print(now.month(), DEC);
Serial.print("/");
Serial.print(now.year(), DEC);
Serial.print(" ");
Serial.print(now.hour(), DEC);
Serial.print(":");
Serial.print(now.minute(), DEC);
Serial.print(":");
Serial.print(now.second(), DEC);
#endif //ECHO_TO_SERIAL
// read the analog in value:
/* analogRead(analogInPinPanPos);
delay(10);
int sensorValuePanPos = analogRead(analogInPinPanPos);*/
analogRead(analogInPinPanNeg);
delay(10);
int sensorValuePanNeg = analogRead(analogInPinPanNeg);
analogRead(analogInPinBat);
delay(10);
int sensorValueBat = analogRead(analogInPinBat);
/*float v_pinPanPos = Vcc*sensorValuePanPos/1023;
float v_PanPos = v_pinPanPos/(R2/(R1+R2));*/
float v_pinPanNeg = Vcc*sensorValuePanNeg/1023;
float v_PanNeg = v_pinPanNeg/(R4/(R3+R4));
float v_pinBat = Vcc*sensorValueBat/1023;
float v_Bat = v_pinBat/(R6/(R5+R6));
float v_Pan = (v_Bat - v_PanNeg) * ;
#if ECHO_TO_SERIAL
//for debugging
Serial.print("; ");
Serial.print(sensorValuePanPos);
Serial.print("; ");
Serial.print(sensorValuePanNeg);
Serial.print("; ");
Serial.print(sensorValueBat);
/*Serial.print("; ");
Serial.print(v_PanPos);*/
Serial.print("; ");
Serial.print(v_PanNeg);
Serial.print("; ");
Serial.print(v_Pan);
Serial.print("; ");
Serial.println(v_Bat);
#endif //ECHO_TO_SERIAL
delay(100);
digitalWrite(greenLEDpin, LOW);
PanStats.add(v_Pan);
BatStats.add(v_Bat);
if ((PanStats.count() == 120) && (BatStats.count() == 120))
{
// log time
logfile.print(now.day(), DEC);
logfile.print("/");
logfile.print(now.month(), DEC);
logfile.print("/");
logfile.print(now.year(), DEC);
logfile.print(" ");
logfile.print(now.hour(), DEC);
logfile.print(":");
logfile.print(now.minute(), DEC);
logfile.print(":");
logfile.print(now.second(), DEC);
//log data
logfile.print("; ");
logfile.print(PanStats.average(), 2);
logfile.print("; ");
logfile.println(BatStats.average(), 2);
logfile.println();
#if ECHO_TO_SERIAL
Serial.println("=====================================");
Serial.print(" Count: ");
Serial.println(PanStats.count());
Serial.print(" v_Pan Min: ");
Serial.println(PanStats.minimum(),2);
Serial.print(" v_Bat Min: ");
Serial.println(BatStats.minimum(),2);
Serial.print(" v_Pan Max: ");
Serial.println(PanStats.maximum(),2);
Serial.print(" v_Bat Max: ");
Serial.println(BatStats.maximum(),2);
Serial.print(" v_Pan Moyenne: ");
Serial.println(PanStats.average(), 2);
Serial.print(" v_Bat Moyenne: ");
Serial.println(BatStats.average(), 2);
Serial.println("=====================================");
Serial.println();
#endif // ECHO_TO_SERIAL
PanStats.clear();
BatStats.clear();
delay(10);
// blink LED to show we are syncing data to the card & updating FAT!
digitalWrite(redLEDpin, HIGH);
logfile.flush();
delay(500);
digitalWrite(redLEDpin, LOW);
}
}
