+ version 0.1.01

+ optimized _read() function for speed based upon numbers from datasheet + some refactoring + added demo2 - delta-read + added demo3 - measure timing

Author: RobTillaart

libraries/MAX31855/MAX31855.cpp

@@ -1,7 +1,7 @@
 //
 // FILE: MAX31855.cpp
 // AUTHOR: Rob Tillaart
-// VERSION: 0.1.00
+// VERSION: 0.1.01
 // PURPOSE: MAX31855 - Thermocouple
 // DATE: 2014-01-01
 // URL:
@@ -11,7 +11,7 @@
 
 #include "MAX31855.h"
 
-MAX31855::MAX31855(uint8_t sclk, uint8_t cs, uint8_t miso) 
+MAX31855::MAX31855(uint8_t sclk, uint8_t cs, uint8_t miso)
 {
  _sclk = sclk;
  _cs = cs;
@@ -30,57 +30,49 @@ void MAX31855::begin()
 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 *= -1;
  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 18-31
  _temperature = (value & 0x1FFF) * 0.25;
  if (value & 0x2000) _temperature *= -1;
- 
+
  return _status;
 }
 
-
-uint32_t MAX31855::_read(void) 
+uint32_t MAX31855::_read(void)
 {
  uint32_t value = 0;
 
- digitalWrite(_sclk, LOW);
- delayMicroseconds(1000);
  digitalWrite(_cs, LOW);
- delayMicroseconds(1000);
 
- for (int8_t i=31; i>=0; i--)
+ for (int8_t i = 31; i >= 0; i--)
  {
- digitalWrite(_sclk, LOW);
- delayMicroseconds(1000);
- 
  value <<= 1;
- if (digitalRead(_miso) == HIGH) value += 1;
- 
+ digitalWrite(_sclk, LOW);
+ if ( digitalRead(_miso) ) value += 1;
  digitalWrite(_sclk, HIGH);
- delayMicroseconds(1000);
  }
 
  digitalWrite(_cs, HIGH);
- 
+
  return value;
 }
 

libraries/MAX31855/MAX31855.h

@@ -3,7 +3,7 @@
 //
 // FILE: MAX31855.h
 // AUTHOR: Rob Tillaart
-// VERSION: 0.1.00
+// VERSION: 0.1.01
 // PURPOSE: MAX31855 - Thermocouple
 // DATE: 2014-01-01
 // URL:
@@ -17,14 +17,14 @@
 #include "Arduino.h"
 #endif
 
-#define MAX31855_VERSION "0.1.00"
+#define MAX31855_VERSION "0.1.01"
 
 #define STATUS_OK 0x00
 #define STATUS_OPEN_CIRCUIT 0x01
 #define STATUS_SHORT_TO_GND 0x02
 #define STATUS_SHORT_TO_VCC 0x04
 
-class MAX31855 
+class MAX31855
 {
 public:
  MAX31855(uint8_t SCLK, uint8_t CS, uint8_t MISO);
@@ -40,10 +40,12 @@ class MAX31855
  float _internal;
  float _temperature;
  uint8_t _status;
- 
+
  uint8_t _sclk;
  uint8_t _miso;
  uint8_t _cs;
 };
 
-#endif
+#endif
+
+// END OF FILE

libraries/MAX31855/examples/max31855_demo2/max31855_demo2.ino

@@ -0,0 +1,43 @@
+//
+// FILE: max31855_demo2.ino
+// AUTHOR: Rob Tillaart
+// VERSION: 0.1.01
+// PURPOSE: thermocouple lib demo application
+// DATE: 2014-01-02
+// URL:
+//
+// Released to the public domain
+//
+
+#include "MAX31855.h"
+
+const int doPin = 7;
+const int csPin = 6;
+const int clPin = 5;
+
+MAX31855 tc(clPin, csPin, doPin);
+
+void setup() 
+{
+ Serial.begin(115200);
+ Serial.print("Start max31855_demo: ");
+ Serial.println(MAX31855_VERSION);
+ Serial.println();
+
+ tc.begin();
+ tc.read();
+}
+
+void loop() 
+{
+ float t1 = tc.getTemperature();
+ delay(1000);
+ tc.read();
+ float t2 = tc.getTemperature();
+ Serial.print("delta:\t");
+ Serial.println(t2-t1, 2);
+ delay(1000);
+}
+
+
+

libraries/MAX31855/examples/max31855_demo3/max31855_demo3.ino

@@ -0,0 +1,57 @@
+//
+// FILE: max31855_demo2.ino
+// AUTHOR: Rob Tillaart
+// VERSION: 0.1.01
+// PURPOSE: thermocouple lib demo application
+// DATE: 2014-01-02
+// URL:
+//
+// Released to the public domain
+//
+
+#include "MAX31855.h"
+
+const int doPin = 7;
+const int csPin = 6;
+const int clPin = 5;
+
+MAX31855 tc(clPin, csPin, doPin);
+
+void setup() 
+{
+ Serial.begin(115200);
+ Serial.print("Start max31855_demo: ");
+ Serial.println(MAX31855_VERSION);
+ Serial.println();
+
+ tc.begin();
+
+ uint32_t start = micros();
+ tc.read();
+ uint32_t stop = micros();
+ Serial.print("read:\t");
+ Serial.println(stop - start);
+
+ start = micros();
+ float t1 = tc.getTemperature();
+ stop = micros();
+ Serial.print("getTemperature:\t");
+ Serial.println(stop - start);
+
+ start = micros();
+ tc.getInternal();
+ stop = micros();
+ Serial.print("getInternal:\t");
+ Serial.println(stop - start);
+
+ Serial.println(t1,2);
+}
+
+void loop() 
+{
+}
+
+
+
+
+