mirror of
https://github.com/RobTillaart/Arduino.git
synced 2024-10-03 18:09:02 -04:00
106 lines
2.3 KiB
C++
106 lines
2.3 KiB
C++
//
|
|
// FILE: MAX31855.cpp
|
|
// AUTHOR: Rob Tillaart
|
|
// VERSION: 0.1.08
|
|
// PURPOSE: MAX31855 - Thermocouple
|
|
// DATE: 2014-01-01
|
|
// URL: http://forum.arduino.cc/index.php?topic=208061
|
|
//
|
|
// HISTORY:
|
|
// 0.1.08 2015-12-06 replaced all temperature calls with one TCfactor + update demos.
|
|
// 0.1.07 2015-12-06 updated TC factors from the MAX31855 datasheet
|
|
// 0.1.06 2015-12-05 added support for other types of TC's (experimental)
|
|
// 0.1.05 2015-07-12 refactor robust constructor
|
|
// 0.1.04 2015-03-09 replaced float -> double (ARM support)
|
|
// 0.1.03 fixed negative temperature
|
|
// 0.1.02 added offset
|
|
// 0.1.01 refactored speed/performance
|
|
// 0.1.00 initial version.
|
|
//
|
|
// Released to the public domain
|
|
//
|
|
|
|
#include "MAX31855.h"
|
|
|
|
MAX31855::MAX31855(uint8_t sclk, uint8_t cs, uint8_t miso)
|
|
{
|
|
_sclk = sclk;
|
|
_cs = cs;
|
|
_miso = miso;
|
|
_offset = 0;
|
|
_TCfactor = 1;
|
|
_status = STATUS_NOREAD;
|
|
_temperature = -999;
|
|
_internal = -999;
|
|
}
|
|
|
|
void MAX31855::begin()
|
|
{
|
|
pinMode(_cs, OUTPUT);
|
|
digitalWrite(_cs, HIGH);
|
|
|
|
pinMode(_sclk, OUTPUT);
|
|
pinMode(_miso, INPUT);
|
|
}
|
|
|
|
uint8_t MAX31855::read()
|
|
{
|
|
uint32_t value = _read();
|
|
|
|
// process status bit 0-2
|
|
_status = value & 0x0007;
|
|
value >>= 3;
|
|
|
|
// reserved bit 3
|
|
value >>= 1;
|
|
|
|
// process internal bit 4-15
|
|
_internal = (value & 0x07FF) * 0.0625;
|
|
if (value & 0x0800)
|
|
{
|
|
_internal = -128 + _internal; // fix neg temp
|
|
}
|
|
value >>= 12;
|
|
|
|
// Fault bit ignored as we have the 3 status bits
|
|
// _fault = value & 0x01;
|
|
value >>= 1;
|
|
|
|
// reserved bit 17
|
|
value >>= 1;
|
|
|
|
// process temperature bit 18-30 + sign bit = 31
|
|
_temperature = (value & 0x1FFF) * 0.25;
|
|
if (value & 0x2000) // negative flag
|
|
{
|
|
_temperature = -2048 + _temperature; // fix neg temp
|
|
}
|
|
if (_offset != 0) _temperature += _offset;
|
|
|
|
return _status;
|
|
}
|
|
|
|
// TODO: optimize performance by direct port manipulation?
|
|
uint32_t MAX31855::_read(void)
|
|
{
|
|
uint32_t value = 0;
|
|
|
|
digitalWrite(_cs, LOW);
|
|
|
|
for (int8_t i = 31; i >= 0; i--)
|
|
{
|
|
value <<= 1;
|
|
digitalWrite(_sclk, LOW);
|
|
// delayMicroseconds(1); // DUE
|
|
if ( digitalRead(_miso) ) value += 1;
|
|
digitalWrite(_sclk, HIGH);
|
|
// delayMicroseconds(1); // DUE
|
|
}
|
|
|
|
digitalWrite(_cs, HIGH);
|
|
|
|
return value;
|
|
}
|
|
|
|
// END OF FILE
|