UNO R3 + SD + RTC shield - need help in my code (solved)

Projects Programming
1

Good day everyone, I am new in arduino coding
Trying to logger co2 & temp data from mhz19b, with timestamp from rtc
hardware setup uno + sd shield with rtc ds1307, and co2 sensor
in serial monitor data normal on co2, temp & rtc but only rtc write in sd card
I need help on "get logvalue"
my code :


//  Variable declaration: Lists all the variables used in the program

#include "SoftwareSerial.h"
#include "MHZCO2.h"
#include <SPI.h>
#include <SD.h>
#include <Wire.h>
#include "RTClib.h"

const int RX = 9;
const int TX = 8;
SoftwareSerial ss(TX, RX);
MHZ19B MHZ19B;

const int chipSelect = 10; //10 is default by shield, but normally on Pin 4
int interval = 30;  //Log to SD Card every 30 seconds

long timer;
String timestring;
String mvalue;

RTC_DS1307 rtc;


// >>>>>>>>>>>>>>>>>  Setup: Executes once when the Arduino is powered on
void setup()
{ Serial.begin(9600);
delay(2000);
  Serial.println("Hello World");
  Serial.println("Data Logger");
  Serial.println("------------------");
  MHZ19B.begin(&ss);
  ss.begin(9600); 
  delay(1000);
  Serial.println("Initializing SD card...");
  if (!SD.begin(chipSelect)) {
    Serial.println("SD Card error");
    return;
  }
  Serial.println("card initialized");
  if (! rtc.begin()) {
    Serial.println("No RTC found");
  } else {
    Serial.println("RTC clock found");
  }
  if (! rtc.isrunning()) {
    Serial.println("RTC is not configured");
  }
}

//  Loop: Executes repeatedly
void loop(){

  MHZ19B.measure();

  Serial.println("------------------");


  delay(30000);

  if ((timer + interval * 1000) < millis()) {
    timer = millis();
    get_logvalue(); //Get your value
    get_time(); //Get time from RTC
    write_data(); //Write value and Time to SD
  }
}

void get_time(){ //Read Time from RTC
  DateTime now = rtc.now();
  timestring = now.day();
  timestring += "-";
  timestring += now.month();
  timestring += "-";
  timestring += now.year();
  timestring += " ";
  timestring += now.hour();
  timestring += ":";
  timestring += now.minute();
  timestring += ":";
  timestring += now.second();
  Serial.println(timestring);
}

void get_logvalue() {
  mvalue = "My Value"; //mvalue is your log parameter eg. Temperature
  Serial.print("CO2:  ");
  Serial.println(MHZ19B.getCO2());
  Serial.print("Temp: ");
  Serial.println(MHZ19B.getTemperature());

 
}

void write_data() { //Write to SD card
  String dataString = mvalue + "," + timestring;
  File dataFile = SD.open("datalog1.txt", FILE_WRITE);
  if (dataFile) {
    dataFile.println(dataString);
    dataFile.close();
    Serial.println(dataString);
  }
  else {
    Serial.println("error writing datalog1.txt");
  }
}
2

What help do you need?

I guess you need to add the sensor values to mvalue in that function. Have you tried doing that like you did with timestring?

3

Hi PaulRB,
I need help to fill "mvalue" with measurement value from (MHZ19B.getCO2()) & (MHZ19B.getTemperature())

void get_logvalue() {
  mvalue = "My Value"; //mvalue is your log parameter eg. Temperature
  Serial.print("CO2:  ");
  Serial.println(MHZ19B.getCO2());
  Serial.print("Temp: ");
  Serial.println(MHZ19B.getTemperature());
4

Ok.

5

problem solved


```cpp
void get_logvalue() {
  mvalue = MHZ19B.measure(); 

// Trial code
                  
  mvalue += MHZ19B.getCO2();
  mvalue += ",";
  mvalue += MHZ19B.getTemperature();
  mvalue += ",";
  mvalue += sht31.readTemperature();
  mvalue += ",";
  mvalue += sht31.readHumidity();

   Serial.println(mvalue);
}
6

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