Tiit Rätsep
Library for MAX31855. Based on MAX6675 library. I have only implemented the temperature reading. The chip supports also the reading of internal reference temperature and faults for shorted thermocouple and shorts to vcc/gnd.
Revision 0:a07644a18427, committed 2012-03-10
- Comitter:
- ratsept
- Date:
- Sat Mar 10 19:30:40 2012 +0000
- Commit message:
Changed in this revision
| MAX31855.cpp | Show annotated file Show diff for this revision Revisions of this file |
| MAX31855.h | Show annotated file Show diff for this revision Revisions of this file |
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/MAX31855.cpp Sat Mar 10 19:30:40 2012 +0000
@@ -0,0 +1,46 @@
+#include <mbed.h>
+#include "MAX31855.h"
+
+ MAX31855::MAX31855(SPI& _spi, PinName _ncs) : spi(_spi), ncs(_ncs)
+{
+ deselect();
+}
+
+float MAX31855::read_temp()
+{
+ short value = 0;
+ float temp = 0;
+
+ int16_t response = 0;
+ uint8_t resp_byte = 0;
+
+ select();
+
+ resp_byte = spi.write(0);
+ response |= resp_byte << 8;
+ resp_byte = spi.write(0);
+ response |= resp_byte << 0;
+
+ deselect();
+
+ if (response & 0x0001)
+ {
+ error("Error");
+ return 2000.0;
+ }
+
+ response &= 0xfffc; // mask lower two bits
+ temp = response / 16.0;
+
+ return temp;
+}
+
+void MAX31855::select()
+{
+ ncs = 0;
+}
+
+void MAX31855::deselect()
+{
+ ncs = 1;
+}
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/MAX31855.h Sat Mar 10 19:30:40 2012 +0000
@@ -0,0 +1,25 @@
+#ifndef MAX31855_h
+#define MAX31855_h
+
+#include "mbed.h"
+
+class MAX31855
+{
+ SPI& spi;
+ DigitalOut ncs;
+ public:
+
+ MAX31855(SPI& _spi, PinName _ncs);
+ void select();
+ void deselect();
+
+ float read_temp();
+ private:
+ PinName _CS_pin;
+ PinName _SO_pin;
+ PinName _SCK_pin;
+ int _units;
+ float _error;
+};
+
+#endif
\ No newline at end of file