/*
* Battery Capacity Checker
* Uses Nokia 5110 Display
* Uses 1 Ohm power resister as shunt – Load can be any suitable resister or lamp
*
* Based on a concept by Adam Welch http://AdamWelch.Uk
*
* Required Library – LCD5110_Graph.h – http://www.rinkydinkelectronics.com/library.php?id=47
*/

#include "LCD5110_Graph.h"
LCD5110 myGLCD(5, 6, 7, 9, 8); // Setup Nokia 5110 Screen SCLK/CLK=5, DIN/MOSI/DATA=6, DC/CS=7, RST=9 Chip Select/CE/SCE=8,
extern uint8_t SmallFont[];
extern uint8_t MediumNumbers[];

#define gatePin 10
#define highPin A0
#define lowPin A1

boolean finished = false;
int printStart = 0;
int interval = 5000; //Interval (ms) between measurements

float mAh = 0.0;
float shuntRes = 1.0; // In Ohms – Shunt resistor resistance
float voltRef = 4.71; // Reference voltage (probe your 5V pin)
float current = 0.0;
float battVolt = 0.0;
float shuntVolt = 0.0;
float battLow = 2.9;

unsigned long previousMillis = 0;
unsigned long millisPassed = 0;

void setup() {

Serial.begin(9600);
Serial.println("Battery Capacity Checker v1.1");
Serial.println("battVolt current mAh");

pinMode(gatePin, OUTPUT);
digitalWrite(gatePin, LOW);

myGLCD.InitLCD(); //initialize LCD with default contrast of 70
myGLCD.setContrast(68);
myGLCD.setFont(SmallFont); // Set default font size. tinyFont 4×6, smallFont 6×8, mediumNumber 12×16, bigNumbers 14×24
myGLCD.clrScr();

myGLCD.print("Battery",CENTER,0);
myGLCD.print("Check",CENTER,12);
myGLCD.print("Please Wait",CENTER,24);
myGLCD.update();
delay(2000);
myGLCD.clrScr();
}

void loop() {

battVolt = analogRead(highPin) * voltRef / 1024.0;
shuntVolt = analogRead(lowPin) * voltRef / 1024.0;

if(battVolt >= battLow && finished == false)
{
digitalWrite(gatePin, HIGH);
millisPassed = millis() – previousMillis;
current = (battVolt – shuntVolt) / shuntRes;
mAh = mAh + (current * 1000.0) * (millisPassed / 3600000.0);
previousMillis = millis();

myGLCD.clrScr();
myGLCD.print("Discharge",CENTER,0);
myGLCD.print("Voltage:",0,10);
myGLCD.printNumF(battVolt, 2,50,10);
myGLCD.print("v",77,10);
myGLCD.print("Current:",0,20);
myGLCD.printNumF(current, 2,50,20);
myGLCD.print("a",77,20);
myGLCD.printNumI(mAh,30,30);
myGLCD.print("mAh",65,30);
myGLCD.print("Running",CENTER,40);
myGLCD.update();

Serial.print(battVolt);
Serial.print("\t");
Serial.print(current);
Serial.print("\t");
Serial.println(mAh);

delay(interval);
}
if(battVolt < battLow)
{
digitalWrite(gatePin, LOW);

finished = true;

if(mAh < 10) {
printStart = 40;
}
else if(mAh < 100) {
printStart = 30;
}
else if(mAh <1000) {
printStart = 24;
}
else if(mAh <10000) {
printStart = 14;
}
else {
printStart = 0;
}

myGLCD.clrScr();
myGLCD.print("Discharge",CENTER,0);
myGLCD.print("Voltage:",0,10);
myGLCD.printNumF(battVolt, 2,50,10);
myGLCD.print("v",77,10);
myGLCD.setFont(MediumNumbers);
myGLCD.printNumI(mAh,printStart,21);
myGLCD.setFont(SmallFont);
myGLCD.print("mAh",65,30);
myGLCD.print("Complete",CENTER,40);
myGLCD.update();

delay(interval * 2);
}
}