batterylogger.ino

/*
 Name:		BatteryLogger.ino
 Created:	5/14/2018 11:02:28 AM
 Author:	tomea
*/
#include <Servo.h>

Servo myServo;

const float PD_FACTOR = 3.504943957968f;
float curFactor = 1.0f;
int32_t voltageBAT_ADC, voltageCUR_ADC, counter;
float voltageBAT, voltageCUR, voltageBAT_a, voltageCUR_a;
bool shouldSpin = 0;
int incomingByte = 0;
int val = 5;

// the setup function runs once when you press reset or power the board
void setup() {
	Serial.begin(9600);

	// Averaging loop
	while (counter <= 1000)
	{
		voltageBAT_ADC += analogRead(A1);
		voltageCUR += analogRead(A0);
		counter += 1;
	}
	// reset averaging counter
	counter = 0;
	// calculated scaled voltage
	voltageBAT_a = (voltageBAT / 1000.0) * (5.0 / 1023.0);
	voltageCUR_a = (voltageCUR / 1000.0) * (5.0 / 1023.0) * curFactor;
	// calculate current factor. At 0A, voltage should be 0.5V, so this makes sure of that
	curFactor = 0.5f / (voltageCUR_a);
	// reset averaging variables
	voltageBAT = 0;
	voltageCUR = 0;

	// initialise servo
	myServo.attach(9);
	myServo.writeMicroseconds(1000);
	delay(2000);
}

// the loop function runs over and over again until power down or reset
void loop() {
	// check is Serial data available
	if (Serial.available() > 0)
	{
		// read incoming byte
		incomingByte = Serial.read();
		if (incomingByte == 83)
			shouldSpin = 1;
		if (incomingByte == 115)
			shouldSpin = 0;
		if (incomingByte == 43)
		{
			val += 5;
			//Serial.println(val);
			if (val > 100)
				val = 100;
		}
		if(incomingByte == 45)
		{
			val -= 5;
			if (val < 0)
				val = 0;
		}
	}
	// map 0-100 to ESC input range
	int writeVal = map(val, 0, 100, 1000, 2000);
	// write PWM value to ESC
	if (shouldSpin)
	{
		myServo.writeMicroseconds(writeVal);
	}
	else if (!shouldSpin)
	{
		myServo.writeMicroseconds(1000);
	}
	

	// averaging loop
	while (counter <= 1000)
	{
		voltageBAT_ADC += analogRead(A1);
		voltageCUR_ADC += analogRead(A0);
		counter += 1;
	}
	// reset averaging counter
	counter = 0;
	// calculate scaled voltages
	voltageBAT_a = (voltageBAT_ADC / 1000.0) * (5.0 / 1023.0) * PD_FACTOR;
	voltageCUR_a = (voltageCUR_ADC / 1000.0) * (5.0 / 1023.0) * curFactor;
	// reset averaging variables
	voltageBAT_ADC = 0;
	voltageCUR_ADC = 0;

	// if ACS770 voltage < 0.5 something has gone wrong, so clamp to 0.5V if it goes below
	if (voltageCUR_a < 0.5)
	{
		voltageCUR_a = 0.5f;
	}
	// if battery voltage goes below 0V something has gone wrong, so clamp to 0V. Unlikely to happen!!
	else if (voltageBAT_a < 0.0f)
	{
		Serial.println("Battery voltage below 0V!!!");
		voltageBAT_a = 0.0f;
	}

	// get actual current using current/mV factor found in ACS770 datasheet.
	float current = (voltageCUR_a - 0.5) / 40e-3;
	
	// Send data over serial. Data sent in format BAT_V,CUR_V,CUR_A\n
	Serial.print(voltageBAT_a, 4);
	Serial.print(",");
	Serial.print(voltageCUR_a, 4);
	Serial.print(",");
	Serial.println(current, 4);
}