DIY arduino based Powered Paragliding flight computer

Introduction :

As powered paraglider motors are air cooled two stroke engines that rely on membrane carburetors plus the fact that the engine needs fine tuning every now and then for the fuel mixture I came up with the idea to build a flight computer that gives the pilot a rich palette of engine information.

Once I had figured out the motor part it became very tempting to plan other functionality.

The status of the project is far from finished so it should be considered a work in progress.
Ultimately it would be nice if I can post a BOM with all the components so others can build one on their own including the 3d printed casing.

Some pictures :

LCD with the clock and themistor readings

The breadboard and the Arduino Mega

Once I have a working basis I would like to make the design modular so everyone can decide for himself what extra features to add or to have a basic model in the beginning and to upgrade when extra features are needed.

It should be understood that most code used in this project is transformed from examples and tutorials and I don`t claim to have started from scratch.

Obviously this project is open source and all suggestions , hints and help are welcome.

Features in progress :

• Cylinder head temperature reading (Celsius) (working)
• Exhaust gas temp reading (Celsius) (working)
• Time (working)
• SD card logging of all readings (working)
• LCD screen with all relevant readings (working)
• Fuel flow sensor (in progress)

Features planned for future :

• Actual Fuel consumption 
• Engine RPM 
• GPS position logging
• Barometric pressure reading for altitude indication
• 3 axis accelerometer for g-force measurements.
• Bluetooth connection to android devices for remote monitoring.
• Averages of fuel consumption and flying range left.

Components used so far :

• Arduino MEGA (might want to replace that with an Arduino DUE)
• Dead-on RTC module
• SD card module 
• 64x8 LCD screen SPI
• 2 thermistors (now for testing will be replaced by thermal sensors for Cylinder head Temp and Exhaust Temp)
• 2 RGB LEDs for indicating the temperature levels (cold , operating temp, overheating)
• 2 normal LEDs for indicating SD card activity and general operating activity

Breadboard view : (warning the LCD is not wired here)

Schematic : (warning the LCD is not wired here)

Code : (warning : work in progress)

#include <math.h>
#include "U8glib.h"
#include <SPI.h>
#include <SD.h>

const int chipSelect_RTC = 11; //chip select for the RTC
const int chipSelect_SD = 12;//chip select for the SD card

int ledr1 = 5 ;
int ledg1 = 6 ;
int ledb1 = 7 ;

int ledr2 = 8 ;
int ledg2 = 9 ;
int ledb2 = 10 ;

int InteruptPin = 18;
int lightPin = 2 ;
int Writeled = 22 ;
int RTCled = 23 ;

String timedate;

int RTC_init(){ 
      //pinMode(chipSelect_RTC,OUTPUT); // chip select
      // start the SPI library:
      SPI.begin();
      SPI.setBitOrder(LSBFIRST); 
      SPI.setDataMode(SPI_MODE3); // both mode 1 & 3 should work 
      //set control register
          digitalWrite(chipSelect_SD, HIGH);
      digitalWrite(chipSelect_RTC, LOW);  
      SPI.transfer(0x8E);
      SPI.transfer(0x67); //60= disable Osciallator and Battery SQ wave @1hz, temp compensation, Alarms enabled interupt enabled
      digitalWrite(chipSelect_RTC, HIGH);
          digitalWrite(chipSelect_SD, HIGH);
}

String ReadTimeDate(){
    String temp;
        RTC_init();
    int TimeDate [7]; //second,minute,hour,null,day,month,year        
    for(int i=0; i<=6;i++){
        if(i==3)
            i++;
        digitalWrite(chipSelect_SD, HIGH);
                digitalWrite(chipSelect_RTC, LOW);
        digitalWrite(RTCled, HIGH);
                SPI.setBitOrder(MSBFIRST);
                SPI.transfer(i+0x00); 
        unsigned int n = SPI.transfer(0x00);        
        digitalWrite(chipSelect_RTC, HIGH);
        digitalWrite(RTCled, LOW);
                int a=n & B00001111;    
        if(i==2){    
            int b=(n & B00110000)>>4; //24 hour mode
            if(b==B00000010)
                b=20;        
            else if(b==B00000001)
                b=10;
            TimeDate[i]=a+b;
        }
        else if(i==4){
            int b=(n & B00110000)>>4;
            TimeDate[i]=a+b*10;
        }
        else if(i==5){
            int b=(n & B00010000)>>4;
            TimeDate[i]=a+b*10;
        }
        else if(i==6){
            int b=(n & B11110000)>>4;
            TimeDate[i]=a+b*10;
        }
        else{    
            int b=(n & B01110000)>>4;
            TimeDate[i]=a+b*10;    
            }
    }
    //temp.concat(TimeDate[4]);
    //temp.concat("/") ;
    //temp.concat(TimeDate[5]);
    //temp.concat("/") ;
    //temp.concat(TimeDate[6]);
    //temp.concat(" ") ;
        if( TimeDate[2] < 10 )
         temp.concat("0");
    temp.concat(TimeDate[2]);
    temp.concat(":") ;
        if( TimeDate[1] < 10 )
          temp.concat("0");
    temp.concat(TimeDate[1]);
    temp.concat(":") ;
        if( TimeDate[0] < 10 )
          temp.concat("0");
    temp.concat(TimeDate[0]);
  digitalWrite(chipSelect_SD, LOW);
  digitalWrite(chipSelect_RTC, HIGH);  
  return(temp);
 }

// setup u8g object
U8GLIB_ST7920_128X64 u8g(2, 3, 4, U8G_PIN_NONE); 

double Thermister(int RawADC) {
  double Temp;
  Temp = log(((10240000/RawADC) - 10000));
  Temp = 1 / (0.001129148 + (0.000234125 * Temp) + (0.0000000876741 * Temp * Temp * Temp));
  Temp = Temp - 273.15;   // Convert Kelvin to Celcius
 
  return Temp;
}

void draw(void) {
  timedate = ReadTimeDate();
  // graphic commands to redraw the complete screen should be placed here  
  digitalWrite(4,LOW);
  u8g.setFont(u8g_font_fixed_v0);
  u8g.setPrintPos(0, 7);
  u8g.print("Engine");
  u8g.drawLine(0, 10, 63, 10 );
  u8g.setPrintPos(0, 20); 
  u8g.print("Temp 1:");
  u8g.print(int(Thermister(analogRead(0))));
  u8g.print("C");
  u8g.setPrintPos(0, 29); 
  u8g.print("Temp 2:");
  u8g.print(int(Thermister(analogRead(1))));
  u8g.print("C");
  u8g.drawLine(0, 32, 63, 32 );
  u8g.setPrintPos(0, 42);
  u8g.print("Fuel");
  u8g.drawLine(0, 45, 63, 45 );
  u8g.setPrintPos(0, 55 ); 
  u8g.print("Left  :");
  u8g.setPrintPos(0, 64 ); 
  u8g.print("Use    :");
  u8g.print(analogRead(lightPin)/100.0);
  u8g.setPrintPos(0, 73 ); 
  u8g.print("Avg/h :");
  u8g.setPrintPos(0, 82 ); 
  u8g.setPrintPos(8, 128 ); 
  u8g.print(timedate);
  digitalWrite(4,HIGH);
}

void EngineLed() {
  if (int(Thermister(analogRead(0)))<25) {
    // Blue LED 
    digitalWrite(ledb1, HIGH);  
    digitalWrite(ledg1, LOW);
    digitalWrite(ledr1, LOW);
    } 
  else if (int(Thermister(analogRead(0)))>30) {
    // Red LED
    digitalWrite(ledr1, HIGH);
    digitalWrite(ledb1, LOW);
    digitalWrite(ledg1, LOW);
    } 
  else {  
    // Green LED
    digitalWrite(ledr1, LOW);
    digitalWrite(ledb1, LOW);
    digitalWrite(ledg1, HIGH);
  }
  if (int(Thermister(analogRead(1)))<25) {
    // Blue LED 
    digitalWrite(ledb2, HIGH); 
    digitalWrite(ledg2, LOW);
    digitalWrite(ledr2, LOW);
    } 
  else if (int(Thermister(analogRead(1)))>30) {
    // Red LED
    digitalWrite(ledr2, HIGH);
    digitalWrite(ledb2, LOW);
    digitalWrite(ledg2, LOW);
    } 
  else {  
    // Green LED
    digitalWrite(ledr2, LOW);
    digitalWrite(ledb2, LOW);
    digitalWrite(ledg2, HIGH);
  }
}

void LogWrite() {
  digitalWrite(chipSelect_SD, LOW);
  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  File dataFile = SD.open("datalog.txt", FILE_WRITE);
  // if the file is available, write to it:
  if (dataFile) {
    digitalWrite(Writeled, HIGH);
    dataFile.print(timedate);
    dataFile.print(" ");
    dataFile.print("Temp 1 : ");
    dataFile.print(int(Thermister(analogRead(0))));
    dataFile.print("C ");
    dataFile.print("Temp 2 : ");
    dataFile.print(int(Thermister(analogRead(1))));
    dataFile.print("USAGE : ");
    dataFile.print(analogRead(lightPin)/100.0);
    dataFile.println(" L");
    dataFile.close();
    digitalWrite(chipSelect_SD, HIGH);
    digitalWrite(Writeled, LOW);
    // print to the serial port too:
    Serial.print(int(Thermister(analogRead(1))));
    Serial.println("C");
  }  
  // if the file isn't open, pop up an error:
  else {
    Serial.println("error opening datalog.txt");
  }
}

void setup(void) {
  // flip screen
  u8g.setRot90();
  Serial.begin(9600);
  attachInterrupt(5, Trigger, RISING);
  pinMode(chipSelect_SD, OUTPUT);
  pinMode(chipSelect_RTC, OUTPUT);
  pinMode(Writeled, OUTPUT);
  pinMode(RTCled, OUTPUT);
  pinMode(ledr1, OUTPUT);
  pinMode(ledg1, OUTPUT);
  pinMode(ledb1, OUTPUT);
  pinMode(ledr2, OUTPUT);
  pinMode(ledg2, OUTPUT);
  pinMode(ledb2, OUTPUT);
  pinMode(53, OUTPUT);
  pinMode(4, OUTPUT);
  digitalWrite(4, HIGH);
  digitalWrite(chipSelect_SD, HIGH);
  digitalWrite(chipSelect_RTC, HIGH);
  Serial.print("Initializing RTC ...");
  RTC_init();
  Serial.print("Initializing SD card ...");
  if (!SD.begin(chipSelect_SD)) {
    Serial.println("Card failed, or not present");
    return;
  }
  Serial.println("card initialized.");
}

void Trigger(void) {
  // picture loop
  u8g.firstPage();  
  do {
    draw();
  } while( u8g.nextPage() );
  LogWrite();  
  EngineLed();
}
  
  

void loop(void) {
  // Nothing to see here
 }

Files for those who want to try it out :

Main arduino code is HERE

Fritzing file is HERE

For the LCD I used the u8glib and you can find that HERE