Cristian Junca / MAX6675

Librería para leer temperatura haciendo comunicación SPI con el integrado MAX6675

max6675.cpp@0:33fb492d139e, 2020-06-08 (annotated)

Committer:
cristian_junca
Date:
Mon Jun 08 23:18:38 2020 +0000
Revision:
0:33fb492d139e
Read temperatura with SPI communication

Who changed what in which revision?

UserRevisionLine numberNew contents of line
cristian_junca 0:33fb492d139e 1 #include "mbed.h"
cristian_junca 0:33fb492d139e 2 #include "max6675.h"
cristian_junca 0:33fb492d139e 3
cristian_junca 0:33fb492d139e 4 max6675::max6675(SPI& _spi, PinName _ss) : spi(_spi), ss(_ss) {
cristian_junca 0:33fb492d139e 5
cristian_junca 0:33fb492d139e 6 }
cristian_junca 0:33fb492d139e 7
cristian_junca 0:33fb492d139e 8 float max6675::read_temp() {
cristian_junca 0:33fb492d139e 9 short value = 0;
cristian_junca 0:33fb492d139e 10 float temp = 0;
cristian_junca 0:33fb492d139e 11
cristian_junca 0:33fb492d139e 12 uint8_t highByte=0;
cristian_junca 0:33fb492d139e 13 uint8_t lowByte=0;
cristian_junca 0:33fb492d139e 14
cristian_junca 0:33fb492d139e 15 select();
cristian_junca 0:33fb492d139e 16 wait(.25); //This delay is needed else it doesn't seem to update the temp
cristian_junca 0:33fb492d139e 17
cristian_junca 0:33fb492d139e 18 highByte = spi.write(0);
cristian_junca 0:33fb492d139e 19 lowByte = spi.write(0);
cristian_junca 0:33fb492d139e 20 deselect();
cristian_junca 0:33fb492d139e 21
cristian_junca 0:33fb492d139e 22 if (lowByte & (1<<2)) {
cristian_junca 0:33fb492d139e 23 error("No Probe");
cristian_junca 0:33fb492d139e 24 } else {
cristian_junca 0:33fb492d139e 25 value = (highByte << 5 | lowByte>>3);
cristian_junca 0:33fb492d139e 26 }
cristian_junca 0:33fb492d139e 27
cristian_junca 0:33fb492d139e 28 temp = (value*0.25); // Multiply the value by 0.25 to get temp in ˚C or
cristian_junca 0:33fb492d139e 29 // * (9.0/5.0)) + 32.0; // Convert value to ˚F (ensure proper floats!)
cristian_junca 0:33fb492d139e 30
cristian_junca 0:33fb492d139e 31 return temp;
cristian_junca 0:33fb492d139e 32 }
cristian_junca 0:33fb492d139e 33
cristian_junca 0:33fb492d139e 34 void max6675::select() {
cristian_junca 0:33fb492d139e 35 ss = 0;
cristian_junca 0:33fb492d139e 36 }
cristian_junca 0:33fb492d139e 37
cristian_junca 0:33fb492d139e 38 void max6675::deselect() {
cristian_junca 0:33fb492d139e 39 ss = 1;
cristian_junca 0:33fb492d139e 40 }