k30_ssd1306.ino

/*
  Basic Arduino example for K-Series sensor
  Created by Jason Berger
  Co2meter.com  
*/


#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


#include "SoftwareSerial.h"

SoftwareSerial K_30_Serial(3,4);  //Sets up a virtual serial port
                                    //Using pin 12 for Rx and pin 13 for Tx


byte readCO2[] = {0xFE, 0X44, 0X00, 0X08, 0X02, 0X9F, 0X25};  //Command packet to read Co2 (see app note)
byte response[] = {0,0,0,0,0,0,0};  //create an array to store the response

//multiplier for value. default is 1. set to 3 for K-30 3% and 10 for K-33 ICB
int valMultiplier = 1;

void setup() 
{
  // put your setup code here, to run once:
  Serial.begin(9600);         //Opens the main serial port to communicate with the computer
  K_30_Serial.begin(9600);    //Opens the virtual serial port with a baud of 9600
   if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }
  display.clearDisplay();
  display.setTextSize(1);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw white text
}

void loop() 
{
  sendRequest(readCO2);
  unsigned long valCO2 = getValue(response);
  //Serial.print("Co2 ppm = ");
  Serial.println(valCO2);

   display.clearDisplay();
   display.setTextSize(1);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw white text
  display.setCursor(0, 0);     // Start at top-left corner
  display.println("K30 CO2 Test");
    display.setTextSize(2);      // Normal 1:1 pixel scale
  display.println();
  display.print("PPM: ");
  display.println(valCO2);
    display.display();
  delay(2000);
  
}

void sendRequest(byte packet[])
{
  while(!K_30_Serial.available())  //keep sending request until we start to get a response
  {
    K_30_Serial.write(readCO2,7);
    delay(50);
  }
  
  int timeout=0;  //set a timeoute counter
  while(K_30_Serial.available() < 7 ) //Wait to get a 7 byte response
  {
    timeout++;  
    if(timeout > 10)    //if it takes to long there was probably an error
      {
        while(K_30_Serial.available())  //flush whatever we have
          K_30_Serial.read();
          
          break;                        //exit and try again
      }
      delay(50);
  }
  
  for (int i=0; i < 7; i++)
  {
    response[i] = K_30_Serial.read();
  }  
}

unsigned long getValue(byte packet[])
{
    int high = packet[3];                        //high byte for value is 4th byte in packet in the packet
    int low = packet[4];                         //low byte for value is 5th byte in the packet

  
    unsigned long val = high*256 + low;                //Combine high byte and low byte with this formula to get value
    return val* valMultiplier;
}