Cristian Junca / MAX6675

Librería para leer temperatura haciendo comunicación SPI con el integrado MAX6675

max6675.cpp

Committer:
cristian_junca
Date:
2020-06-08
Revision:
0:33fb492d139e

File content as of revision 0:33fb492d139e:

#include "mbed.h"
#include "max6675.h"
 
max6675::max6675(SPI& _spi, PinName _ss) : spi(_spi), ss(_ss) {
 
}
 
float max6675::read_temp() {
    short value = 0;
    float temp = 0;
    
    uint8_t highByte=0;
    uint8_t lowByte=0;
    
    select();
    wait(.25); //This delay is needed else it doesn't seem to update the temp
 
    highByte = spi.write(0);
    lowByte = spi.write(0);
    deselect();
 
    if (lowByte & (1<<2)) {
        error("No Probe");
    } else {
        value = (highByte << 5 | lowByte>>3);
    }
    
    temp = (value*0.25); // Multiply the value by 0.25 to get temp in ˚C or
                         //  * (9.0/5.0)) + 32.0;   // Convert value to ˚F (ensure proper floats!)
 
    return temp;
}
 
void max6675::select() {
    ss = 0;
}
 
void max6675::deselect() {
    ss = 1;
}