Temp sensor inquiry for code

Projects General Guidance
1

So I have connected the BME680 Sensor to my 2560 Mega and have been wondering about certain sensor readings. Im fairly new to coding and I know there are formulas but im not sure how to go about converting certain values to different values.

Lets say I wanted to change the temperature reading im getting from Celsuis to Kelvin, and the pressure reading from hPa to kPa.

This is what I have in my code which is a basic BME680 library. Any help would be very much appreciated!

#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include "Adafruit_BME680.h"

#define BME_SCK 13
#define BME_MISO 12
#define BME_MOSI 11
#define BME_CS 10

#define SEALEVELPRESSURE_HPA (1013.25)

Adafruit_BME680 bme; // I2C
//Adafruit_BME680 bme(BME_CS); // hardware SPI
//Adafruit_BME680 bme(BME_CS, BME_MOSI, BME_MISO,  BME_SCK);


void setup() {
  Serial.begin(9600);
  while (!Serial);
  Serial.println(F("BME680 Readings"));

  if (!bme.begin()) {
    Serial.println("UNABLE TO FIND BME680, RECHECK CONNECTIONS PLEASE!");
    while (1);
  }


  bme.setTemperatureOversampling(BME680_OS_8X);
  bme.setHumidityOversampling(BME680_OS_2X);
  bme.setPressureOversampling(BME680_OS_4X);
  bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
  bme.setGasHeater(320, 150); // 320*C for 150 ms


 
}

void loop() {
  if (! bme.performReading()) {
    Serial.println("Reading Failure :(");
    return;
  }
 
  Serial.print("Temperature = ");
  Serial.print(bme.temperature);
  Serial.println(" *C");
  
   
  Serial.print("Pressure = ");
  Serial.print(bme.pressure / 100.0);
  Serial.println(" hPa");

  Serial.print("Humidity = ");
  Serial.print(bme.humidity);
  Serial.println(" %");

  Serial.print("Gas = ");
  Serial.print(bme.gas_resistance / 1000.0);
  Serial.println(" KOhms");

  Serial.print("Approx. Altitude = ");
  Serial.print(bme.readAltitude(SEALEVELPRESSURE_HPA));
  Serial.println(" m");

  Serial.println();
  delay(2000);
}
2

Just read basic physics. Any technical handbook has the answer. Subtract 272.15 from Celsius and You have Kelvin.......

3

Here is how I do temperature conversion. In floating point for F to C subtract 32 then multiply by 1.8. To do it the other way again in floating point. Take the C temperature and multiply it by 1.8 then add 32. for the pressure conversion it is a ratio of 10, either multiply or divide by 10 depending on which way you want to convert. 1 hPa = 0.1 kPa or 10 kPa = 1 hPa. the difference in C to absolute zero is 272.15 so 0C = 272.15 K.

4

this part I understand. It's putting it into code that I'm lost.

5 
  Serial.print("Temperature = ");
  Serial.print(bme.temperature + 273.15);
  Serial.println(" *K");

  Serial.print("Pressure = ");
  Serial.print(bme.pressure / 1000.0);
  Serial.println(" kPa");

Leo..

6

this worked great! thank you! Im new to this so I was playing around with numbers but Im glad to see how simple it really is! thank you!!!

7

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