Float_Disassemble_Reassemble

float_Disassemble_Reassemble.ino

/*
 * 
 * Sketch to show how to get the single bytes out of a float variable and resemble them to a new variable with the original Value.
 * Can be used e. g. for the transfer via SPI, where only one byte at a time can be sent
 * 
 * Robert Mollik 2016
 * 
 * Created in the content of the development of my weather station and the need to tranfser values via SPI.
 * 
 */

float temperature = -34.3;   // Original variable with example value

// Single bytes of the float variable. Can be a local variable. However I want to send the values in an interrupt.
// For that reason, I want to avoid unnecessary calculations in the interrupt and instead calulate it in the main loop,
// so that they can be assessed in the interrup.

byte temp_0 = 0;
byte temp_1 = 0;
byte temp_2 = 0;
byte temp_3 = 0;

void setup() {
  
  Serial.begin(115200); // start serial monitor

}

void loop() {

  // Create pointer variables for temperature
  // Cast pointer variables into byte
  
  byte * tempPTR = (byte*)&temperature;


  // Read all 4 bytes of the floats and write them into the transfer variable (byte)
  
  temp_0 = tempPTR[0];    //  temp_0 = *(tempPTR);    
  temp_1 = tempPTR[1];    //  temp_1 = *(tempPTR+1);  
  temp_2 = tempPTR[2];    //  temp_2 = *(tempPTR+2);
  temp_3 = tempPTR[3];    //  temp_3 = *(tempPTR+3); 


  // Create new variables for the temperature

  float newTemp = 0;


  // Create pointer variables for the new temperature
  // Cast pointer variables into byte
  
  byte * newTempPTR = (byte*)&newTemp;

  // write transfered bytes into the position of the new float variables

  newTempPTR[0]=temp_0;
  newTempPTR[1]=temp_1;
  newTempPTR[2]=temp_2;
  newTempPTR[3]=temp_3;

  // Display the results via the serial monitor:
  
  Serial.print("Temperature: ");
  Serial.print(temperature,DEC);
  Serial.println();
  
  Serial.print("temp_0: ");
  Serial.print(temp_0,BIN);
  Serial.print(" || ");
  Serial.print("temp_1: ");
  Serial.print(temp_1,BIN);
  Serial.print(" || ");
  Serial.print("temp_2: ");
  Serial.print(temp_2,BIN);
  Serial.print(" || ");
  Serial.print("temp_3: ");
  Serial.print(temp_3,BIN);
  Serial.println();

  Serial.print("temp_0: ");
  Serial.print(temp_0,DEC);
  Serial.print(" || ");
  Serial.print("temp_1: ");
  Serial.print(temp_1,DEC);
  Serial.print(" || ");
  Serial.print("temp_2: ");
  Serial.print(temp_2,DEC);
  Serial.print(" || ");
  Serial.print("temp_3: ");
  Serial.print(temp_3,DEC);
  Serial.println();  
  
  Serial.print("tempPTR: ");
  Serial.print((uint16_t) tempPTR,HEX);
  Serial.print(" || ");
  Serial.print("newTempPTR: ");
  Serial.print((uint16_t) newTempPTR,HEX);
  Serial.println();

  Serial.print("New Temperature: ");
  Serial.print(newTemp,DEC);
  Serial.println();  

  Serial.println();  
  Serial.println("#############################################################################");    
  Serial.println();

  delay(5000);


}