Diff: MAX31850.cpp

Revision:

0:5d39f2521173

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MAX31850.cpp	Mon Mar 09 11:55:54 2015 +0000
@@ -0,0 +1,125 @@
+/**
+* @file MAX31850.cpp
+* @brief library of MAX31850  1-Wire Thermocouple-to-Digital Converters,Cold-Junction Compensated  (http://www.maximintegrated.com/datasheet/index.mvp/id/7953)
+* @author Frederic BLANC
+* @date 2014_01_15
+*/
+#include "mbed.h"
+#include "onewire.h"
+#include "MAX31850.h"
+#include "crc8.h"
+#include "Horner_ITS90.h"
+int MAX31850_Read_Scratch(uint8_t id[],uint8_t sp[],uint8_t n)
+{
+    if (id[0] == MAX31850_ID) {
+        if (ow_reset(n))                 //reset OW
+            return OW_SHORT_CIRCUIT;
+        sp[0]=MAX31850_READ;   // command
+        ow_command(n,sp[0], &id[0]);
+        for ( int i=0 ; i< MAX31850_SP_SIZE; i++ ) { //read 8xdata + CRC16
+            sp[i]=ow_byte_rd(n);
+        }
+        if(sp[8]!=crc8(sp,8))
+            return OW_ERROR_CRC;
+        return OW_OK;
+    }
+    return OW_ERROR_BAD_ID;
+}
+
+int MAX31850_Temp_TRUE(uint8_t *sp,double *temp)
+{
+
+
+    float temp_cj,temp_tc;
+    double vtc;
+    int err; 
+    
+    err = MAX31850_Temp_TC(sp,&temp_tc);
+    if(err) {
+        return err;
+    }
+    MAX31850_Temp_CJ(sp,&temp_cj);
+
+    vtc = MAX31850_K * temp_tc ;
+    *temp=0;
+    if(temp_tc < 0.0) {
+        for(int i=0;i<10;++i)
+        {
+        
+        *temp+=ITS90_TCK_subzero[i]*pow(vtc,i);
+        }
+    } else if(temp_tc < 500.0) {
+        for(int i=0;i<10;++i)
+        {
+        
+        *temp+=ITS90_TCK_sub500[i]*pow(vtc,i);
+        }
+    } else {
+        for(int i=0;i<10;++i)
+        {
+        
+        *temp+=ITS90_TCK_sub1372[i]*pow(vtc,i);
+        }
+    }
+    return OW_OK;
+}
+
+
+int MAX31850_Temp_TC(uint8_t *sp,float *temp)
+{
+
+    uint8_t *ptr_meas;
+    uint16_t meas;
+
+    if(sp[0]& 1)
+        return MAX31850_ERR_FAULT;
+    if(sp[2]& (1<<1))
+        return MAX31850_ERR_OPEN_CIRCUIT;
+    if(sp[2]& (1<<2))
+        return MAX31850_ERR_SHORT2GND;
+    if(sp[2]& (1<<3))
+        return MAX31850_ERR_SHORT2VDD;
+    ptr_meas=(uint8_t*) &meas;
+    *ptr_meas = sp[0]  ;  // LSB
+    *++ptr_meas = sp[1]; // MSB
+    if ( meas & 0x8000 )  {
+
+        meas ^= 0xffff;  // convert to positive => (twos complement)++
+        meas++;
+        *temp= -1.0 * MAX31850_ADC_TEMP_TC_UNIT * (float)(meas>>2);
+    } else {
+        *temp=  MAX31850_ADC_TEMP_TC_UNIT * (float)(meas>>2);
+    }
+
+    return OW_OK;
+}
+
+int MAX31850_Temp_CJ(uint8_t *sp,float *temp)
+{
+    uint8_t *ptr_meas;
+    uint16_t meas;
+
+    ptr_meas=(uint8_t*) &meas;
+    *ptr_meas = sp[2]  ;  // LSB
+    *++ptr_meas = sp[3]; // MSB
+    if ( meas & 0x8000 )  {
+
+        meas ^= 0xffff;  // convert to positive => (twos complement)++
+        meas++;
+        *temp= -1.0 * MAX31850_ADC_TEMP_CJ_UNIT * (float)(meas>>4);
+    } else {
+        *temp=  MAX31850_ADC_TEMP_CJ_UNIT * (float)(meas>>4);
+    }
+    return OW_OK;
+}
+
+int MAX31850_Start_meas(uint8_t id[],uint8_t n=0)
+{
+    if (id[0] == MAX31850_ID) {
+        if (ow_reset(n))                 //reset OW
+            return OW_SHORT_CIRCUIT;
+        ow_command(n,MAX31850_CONVERT_T, &id[0]);
+        return OW_OK;
+    }
+    return OW_ERROR_BAD_ID;
+}
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