File content as of revision 0:f70b1d60f794:

#include "mbed.h"
#include "pwm_tone.h"   /* Tone library for Buzzer Click */
#include "Hexi_OLED_SSD1351.h" /* Header file for OLED Display */
#include "string.h"
#include "Hexi_KW40Z.h"   /* Driver for button presses and BLE */
#include <math.h>       /* Used for ADC conversion algorithm */
#include <iostream>   /* Used for debugging */

/*****Function Prototypes*****/
void readSensors();
void ledColor();
void led_out();
void buzzer();
void CalculatePPM();

PwmOut Buzzer(PTA10);   /* Buzzer is attached to docking station port 1 */

AnalogIn AQSensor(PTB3);   /* Air Quality sensor is attached to docking station port 2 */
AnalogIn COSensor(PTB6);   /* Carbon Monoxide sensor is attached to docking station port 3 */

BusOut led(PTC8, PTD0, PTC9);   /* RGB Port Configurations */

const int green = 5,
          red = 6,          /* LED Colors */
          black = 7,
          yellow = 4;
          
bool is_sounding = false;       /* Set to high if the buzzer is going off */
          
int led_color;      /* Variable to hold the current LED color */

Ticker sensor_read,      /* Used for the read sensor subroutine call */
       buzzer_sound,     /* Used for the sound buzzer subroutine call */
       led_flash,        /* Used to determine the flash rate */
       ledcolor,        /* Used to determine the LED color */
       A2D_Convert;    /* Used to convert the analog signal to digital */

float B_4 = 1000000/Ti4,    /* Tones that will play on the buzzer click */
      B_5 = 1000000/Ti5;
      
char text[20];  /* Static Text Buffer for OLED Display */
char AQ_level[20]; /* Dynamic Text Buffer for AQ total */
char CO_level[20]; /* Dynamic Text Buffer for CO total */
char average[20]; /* Dynamic Text Buffer for the Average total */
char total_total[20]; /* Dynamic Text Buffer for the Total total */

/* Either unit16_t or float */
double   total,    /* Variable to store the total total */
         aq_ppm,   /* Variable used to store the AQ PPM */
         co_ppm,   /* Variable used to store the CO PPM */ 
         avg;      /* Variable to store the average total */
         
uint16_t aq_total, /* Variable to store the AQ total */
         co_total; /* Variable to store the CO total */          
      
int main(){

    /* Instantiate the SSD1351 OLED Driver */ 
    SSD1351 oled(PTB22,PTB21,PTC13,PTB20,PTE6, PTD15);
    
    /* Get OLED Class Default Text Properties */
    oled_text_properties_t textProperties = {0};
    oled.GetTextProperties(&textProperties);
    
    /* Turns on the OLED Display*/
    oled.PowerON();
    
    /* Fills the screen with solid black */         
    oled.FillScreen(COLOR_BLACK);
    
    /* Display 'GAS LEVELS' at (x = 13,y = 0) */
    strcpy((char *) text,"GAS LEVELS");
    oled.Label((uint8_t *)text,13,0);
    
    /* Change font color to green for Air Quality */ 
    textProperties.fontColor   = COLOR_GREEN;
    oled.SetTextProperties(&textProperties);
    
    /* Display 'Air Quality: ' at (x = 0, y = 20) */ 
    strcpy(text,"AQ: ");
    oled.Label((uint8_t *)text,0,20);
    
    /* Change font color to red for Carbon Monoxide */
    textProperties.fontColor   = COLOR_RED;
    oled.SetTextProperties(&textProperties);
    
    /* Display 'CO: ' at (x = 0, y = 40) */
    strcpy(text, "CO: ");
    oled.Label((uint8_t *)text,0,40);
    
    /* Change font color to blue for Average and Total total */
    textProperties.fontColor   = COLOR_BLUE;
    oled.SetTextProperties(&textProperties);
    
    /* Display 'Average: ' at (x = 0, y = 60) */
    strcpy(text, "Average: ");
    oled.Label((uint8_t *)text, 0, 60);
    
    /* Display 'Total: ' at (x = 0, y = 80) */
    strcpy(text, "Total: ");
    oled.Label((uint8_t *)text,0,80);
    
    /* Set text properties to white and right aligned for the dynamic text */
    textProperties.fontColor = COLOR_WHITE;
    textProperties.alignParam = OLED_TEXT_ALIGN_RIGHT;
    oled.SetTextProperties(&textProperties);
    
    /* Subroutine Calls */
    sensor_read.attach(&readSensors, 1);   /* Read the sensor on a time interval (Currently 3s) */
    A2D_Convert.attach(&CalculatePPM, 1);  /* Convert the values read from the sensors to 16 bit integers */
    ledcolor.attach(&ledColor, 0.5);       /* Determine the LED color */
    led_flash.attach(&led_out, 0.25);      /* Flash LED based on sensor data */
    buzzer_sound.attach(&buzzer, 0.25);    /* Sensor values are sent to buzzer function */
    
    while (1) { /* Loop to process and display data */
        
        /*                                       */
        /*                                       */
        /*                                       */
        /* Code to process sensor data goes here */
        /*                                       */
        /*                                       */
        /*                                       */
        
        sprintf(AQ_level,"%.2f",aq_ppm);    /* Print the AQ PPM to the screen */
        
        /* Display time reading in 35px by 15px textbox at(x=55, y=40) */
        oled.TextBox((uint8_t *)AQ_level,55,20,35,15); //Increase textbox for more digits
        
        sprintf(CO_level,"%.2f",co_ppm);    /* Print the CO PPM to the screen */
        
        oled.TextBox((uint8_t *)CO_level,55,40,35,15);
        
        sprintf(average, "%.2f", avg);      /* Print the average to the screen */
        
        oled.TextBox((uint8_t *)average,55,60,35,15);
        
        sprintf(total_total, "%.2f", total);   /* Print the total to the screen */
        
        oled.TextBox((uint8_t *)total_total,55,80,35,15);
        
    }
    
    return 0;
}

void readSensors(){  /* Function to read sensors */
    
    /* Grab the analog signal from the sensors as 16 bit unsigned integers */
    aq_total = AQSensor.read_u16();
    co_total = COSensor.read_u16();
    /* Grab the analog signal from the sensors as floats */
    //aq_total = AQSensor.read();
    //co_total = AQSensor.read();
  
}

void ledColor(){    /* Function to determine the LED color */
    
    if (total <= 10) {
        led = green;
        led_color = led;     /* Store the LED color for the flash function */
    }
    else if (total > 10 && total < 50) {
        led = yellow;
        led_color = led;     /* Store the LED color for the flash function */
    }
    else if (total >= 50) {
        led = red;
        led_color = led;     /* Store the LED color for the flash function */
    }
}

void led_out() { /* Function to flash LEDs */

    if (led == green) {return;}   /* If green, don't blink */
    else if (led == black) {led = led_color;}
    else {led = black;}
     
}

void buzzer() { /* Function to handle the buzzer sound */

    if (total <=25){            /* No buzzer sound if PPM is under 10 */
        Buzzer.period_us(0);
        is_sounding = false;  
    }

    else if (total > 25 and total < 50) {
        if (is_sounding == false){      /* If the buzzer is not triggered, trigger */
            Buzzer.period_us(B_4);      /* Period of B4 */
            Buzzer.write(0.50f);        /* 50% Duty Cycle on the Tone */
            is_sounding = true;         /* Signal that the buzzer is currently triggering */
        }
        else {   
            Buzzer.period_us(0);        /* Turn off the buzzer (Period = 0us)*/
            is_sounding = false;        /* Signal that the buzzer is no longer triggering */
        }        
    }
    
    else if (total >= 50){
        if (is_sounding == false){
            Buzzer.period_us(B_5);      /* Period of B5 */
            Buzzer.write(0.50f);        /* 50% Duty Cycle on the Tone */
            is_sounding = true;
        }
        else {   
            Buzzer.period_us(0);        /* Turn off the buzzer */
            is_sounding = false;
        }
    }   
}

void CalculatePPM(){ /* Function to convert the analog signals to digital based on 16 bit adc steps */
    
    const double AQ_Rl = 20000.0;               // AQ_Rl (20kOhm) - Load resistance for AQ sensor
    const double CO_Rl = 18500.0;               // CO_Rl (18.5kOhm) - Load resistance for CO sensor
    const double Vadc_33 = 0.0000503548;         // ADC step 3,3V/65535 0.00503mV (16bit ADC)
    //const double Vadc_5 = 5.0/65535;          // ADC step 5.0V/2^16 (65535, 16bit ADC)
    double Vrl;                                  // Output voltage
    double Rs;                                   // Rs (Ohm) - Sensor resistance
    double ratio;                                // Rs/Rl ratio
    double lgPPM;

    Vrl = (double)aq_total * Vadc_33;            // For 3.3V Vcc use Vadc_33
    Rs = AQ_Rl * (3.3 - Vrl)/Vrl;                 // Calculate sensor resistance
    ratio = Rs/AQ_Rl;                             // Calculate ratio
    lgPPM = (log10(ratio) * -0.8) + 0.9;       // Calculate air quality ppm
    aq_ppm = 6* pow(10,lgPPM);                 // Calculate air quality ppm
    
    Vrl = (double)co_total * Vadc_33;            // For 3.3V Vcc use Vadc_33
    Rs = CO_Rl * (3.3 - Vrl)/Vrl;                 // Calculate sensor resistance
    ratio = Rs/CO_Rl;                             // Calculate ratio
    lgPPM = (log10(ratio) * -0.8) + 0.9;       // Calculate carbon monoxide ppm
    co_ppm = 6* pow(10,lgPPM);                 // Calculate carbon monoxide ppm
    
    /* Calculate the average and total */
    total = co_ppm + aq_ppm;    
    avg = (total)/2;  
}