/*
    Tims_Electronic_Deviders.ino
    By Tim Jackson.1960

    Creadits:
        Arduino.
        LiquidCrystal_I2C based on work by DFRobot.

    This is code for: Tim's Electronic Deviders.
    I am using 3D Printed Deviders with a 49E Linear Hall Effect Sensor and two Magnets.
    I am using an Arduino NANO to calculate the postion of the deviders from the values recived from the 49E Linear Hall Effect Sensor.
    The sensor is linear: 3 mV/GS, but to get the angle a Sine of the value is calculated.

    S=O/H C=A/H T=O/A
    Degrees to Radians = degrees * (PI / 180)
    Radians to Degrees = radians * 180.0 / pi

*/
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

#define Hall_49R_Pin                    A1        //    define Hall Effect Pin
#define CAL_0                            377        //    Value of hall efect sensor at 0 angle
#define CAL_180                            690        //    Value of hall efect sensor at 180 angle
#define CAL_RANGE (CAL_180 - CAL_0)                //    Highest CAL - Lowest CAL
#define CAL_RAD ((double)CAL_RANGE / 2)            //    Used in the sine H value to get angle.
#define LEG_LENGTH 99                            //    Length of Devider Legs.
#define MAG_BIOS                        -3.11    //    Set to zero, then change to a value that will correct the mesurment about 60 Degrees.
double Angle = 0;                                //    Variable to hold Angle value.
double Length = 0;                                //    Variable to hold Length value.
int SensorValue = CAL_0 + 1;                    //    Variable to hold Sensor value.

LiquidCrystal_I2C lcd(0x27, 16, 2);        //20 to    27    //    Set the LCD address to 0x27 for a 16 chars and 2 line display

void setup()
{
    Serial.begin(115200);            //    Start Serial.
    pinMode(Hall_49R_Pin, INPUT);    //    Define as Input.

    lcd.init();                        //    Start LCD.
    lcd.backlight();                //    Turn on back light.
    lcd.setCursor(0, 0);            //    Set Cursor at the begining of line 0 (Top Line).
    lcd.print(" Angle:");            //    Display Label for Angle on top line.
    lcd.setCursor(0, 1);            //    Set Cursor at the begining of line 1 (Bottom Line).
    lcd.print("Length:");            //    Display Label for Length on bottom line.

}
void loop() {

    SensorValue = analogRead(Hall_49R_Pin);    //    Read the value from sensor.

    Serial.println(SensorValue);            //    Send value to serial.
    CalcAngle();                            //    Do sub routeen for angle.
    CalcLength();                            //    Do sub routeen for length.
    Serial.println();                        //    Send a new line to serial to seperate values.

    delay(200);                                //    Wait a little for things to happen.
}
/*
    Calculate the Angle using Value from Sensor.

        S=O/H
        Radians to Degrees = radians * 180.0 / pi

        O = SensorValue - CAL_0 - CAL_RAD
        H = CAL_RAD
        Angle in radians = asin(O / H)
        Angle in degrees = Angle in radians * 180.0 / pi;

*/
void CalcAngle() {

    double O = (double)SensorValue - CAL_0 - CAL_RAD;
    double H = (double)O / CAL_RAD;
    Angle = 90.0 + (asin(H) * 180.0 / PI);

    Serial.print("Angle ");
    Serial.println(Angle + MAG_BIOS, 4);

    lcd.setCursor(7, 0);
    lcd.print("  ");
    lcd.setCursor(Xpos(Angle + MAG_BIOS), 0);
    lcd.print(Angle + MAG_BIOS, 3);
    lcd.print("  ");

}
/*
    Calculate the Length using degrees calculated from Sensor.

        C=A/H
        A=C*H
        Degrees to Radians = degrees * (PI / 180)

        C = (180 - Angle in degrees) / 2
        H = LEG_LENGTH
        A = C * H
        Length = A * 2

*/
void CalcLength() {

    double _angle = (180.0 - Angle) / 2;
    double _rad = _angle * (PI / 180);
    double C = cos(_rad);
    double H = LEG_LENGTH;
    Length = C * H * 2;

    Serial.print("Length ");
    Serial.println(Length + MAG_BIOS, 4);

    lcd.setCursor(7, 1);
    lcd.print("  ");
    lcd.setCursor(Xpos(Length + MAG_BIOS), 1);
    lcd.print(Length + MAG_BIOS, 3);
    lcd.print("  ");

}
/*
    This a function to calculate the position of value displayed on LCD.

        Check to see if value is hundreds, tens or single.
        To keep numbers alighned.
*/
byte Xpos(byte number) {
    byte val = 8;
    if (number < 100) { val = 9; }
    if (number < 10) { val = 10; }
    return val;
}