72 lines
1.1 KiB
C++
72 lines
1.1 KiB
C++
// this library is public domain. enjoy!
|
|
// www.ladyada.net/learn/sensors/thermocouple
|
|
|
|
#ifdef __AVR
|
|
#include <avr/pgmspace.h>
|
|
#elif defined(ESP8266)
|
|
#include <pgmspace.h>
|
|
#endif
|
|
#include <util/delay.h>
|
|
#include <stdlib.h>
|
|
#include "max6675.h"
|
|
|
|
MAX6675::MAX6675(int8_t SCLK, int8_t CS, int8_t MISO) {
|
|
sclk = SCLK;
|
|
cs = CS;
|
|
miso = MISO;
|
|
|
|
//define pin modes
|
|
pinMode(cs, OUTPUT);
|
|
pinMode(sclk, OUTPUT);
|
|
pinMode(miso, INPUT);
|
|
|
|
digitalWrite(cs, HIGH);
|
|
}
|
|
double MAX6675::readCelsius(void) {
|
|
|
|
uint16_t v;
|
|
|
|
digitalWrite(cs, LOW);
|
|
_delay_ms(1);
|
|
|
|
v = spiread();
|
|
v <<= 8;
|
|
v |= spiread();
|
|
|
|
digitalWrite(cs, HIGH);
|
|
|
|
if (v & 0x4) {
|
|
// uh oh, no thermocouple attached!
|
|
return NAN;
|
|
//return -100;
|
|
}
|
|
|
|
v >>= 3;
|
|
|
|
return v*0.25;
|
|
}
|
|
|
|
double MAX6675::readFahrenheit(void) {
|
|
return readCelsius() * 9.0/5.0 + 32;
|
|
}
|
|
|
|
byte MAX6675::spiread(void) {
|
|
int i;
|
|
byte d = 0;
|
|
|
|
for (i=7; i>=0; i--)
|
|
{
|
|
digitalWrite(sclk, LOW);
|
|
_delay_ms(1);
|
|
if (digitalRead(miso)) {
|
|
//set the bit to 0 no matter what
|
|
d |= (1 << i);
|
|
}
|
|
|
|
digitalWrite(sclk, HIGH);
|
|
_delay_ms(1);
|
|
}
|
|
|
|
return d;
|
|
}
|