Diff: MPL115A2.cpp

Revision:

0:5a72175e5cb2

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MPL115A2.cpp	Mon May 07 13:24:00 2012 +0000
@@ -0,0 +1,266 @@
+/******************************************************************************
+ * Includes
+ ******************************************************************************/
+#include "MPL115A2.h"
+#include "mbed.h"
+
+/******************************************************************************
+ * Constructors
+ ******************************************************************************/
+MPL115A2::MPL115A2(I2C *i2c, const PinName shdnPin):
+_i2c_address(0xc0), _i2c(i2c), _shdnPin(shdnPin),_debug(false),_pc(NULL)
+{
+   
+}
+
+MPL115A2::MPL115A2(I2C *i2c, Serial *pc, const PinName shdnPin):
+_i2c_address(0xc0), _i2c(i2c), _shdnPin(shdnPin), _pc(pc), _debug(true)
+{
+   
+}
+
+/******************************************************************************
+ * Global Functions
+ ******************************************************************************/
+void MPL115A2::ReadSensor()
+{
+    int res;
+
+    //wakeup
+    _shdnPin=1;
+    _bShutdown = false;
+    wait(0.001); // wait the device to be ready
+    
+    // start AD conversions
+    char cmd[2];
+    cmd[0]=0x12;
+    cmd[1]=0x01;
+    res = _i2c->write(_i2c_address,cmd,2);
+    
+    if(_debug)
+    {
+        if(res==0)
+        {
+            _pc->printf("Success: Requested temp and pressure \n");
+        }
+        else
+        {
+            _pc->printf("Failed : Requested temp and pressure %d\n", res);
+        }
+    }
+    
+    wait(0.01);
+    cmd[0]=0x00;
+    res = _i2c->write(_i2c_address,cmd,1);
+    
+    if(_debug)
+    {
+        if(res==0)
+        {
+            _pc->printf("Success: Select temp and pressure register \n");
+        }
+        else
+        {
+            _pc->printf("Failed : Select temp and pressure register %d\n", res);
+        }
+    }    
+    
+    // compensation
+    char data[4];   
+    res = _i2c->read(_i2c_address, data, 4);
+    
+    if(_debug)
+    {
+        if(res==0)
+        {
+            _pc->printf("Success: Read temp and pressure register \n");
+        }
+        else
+        {
+            _pc->printf("Failed : Read temp and pressure register %d\n", res);
+        }
+    }    
+    
+    if(res == 0)
+    {   
+        _uiPadc = (unsigned short) data[0] << 8;
+        _uiPadc += (unsigned short) data[1] & 0x00FF;
+        _uiTadc = (unsigned short) data[2] << 8;
+        _uiTadc += (unsigned short) data[3] & 0x00FF;
+        
+        // Coefficient 9 equation compensation
+        _uiPadc = _uiPadc >> 6;
+        _uiTadc = _uiTadc >> 6;
+    }    
+}
+ 
+ 
+/**********************************************************
+ * GetPressure
+ *  Gets the current pressure from the sensor.
+ *
+ * @return float - The local pressure in kPa
+ **********************************************************/
+float MPL115A2::GetPressure()
+{
+    short siPcomp;
+    int lt1, lt2, lt3, si_c11x1, si_a11, si_c12x2;
+    int si_a1, si_c22x2, si_a2, si_a1x1, si_y1, si_a2x2;
+    
+    // Step 1 c11x1 = c11 * Padc
+    lt1 = (int) _sic11;
+    lt2 = (int) _uiPadc;
+    lt3 = lt1*lt2;
+    si_c11x1 = (int) lt3;
+    
+    // Step 2 a11 = b1 + c11x1
+    lt1 = ((int)_sib1)<<14;
+    lt2 = (int) si_c11x1;
+    lt3 = lt1 + lt2;
+    si_a11 = (int)(lt3>>14);
+    
+    // Step 3 c12x2 = c12 * Tadc
+    lt1 = (int) _sic12;
+    lt2 = (int) _uiTadc;
+    lt3 = lt1*lt2;
+    si_c12x2 = (int)lt3;
+    
+    // Step 4 a1 = a11 + c12x2
+    lt1 = ((int)si_a11<<11);
+    lt2 = (int)si_c12x2;
+    lt3 = lt1 + lt2;
+    si_a1 = (int) lt3>>11;
+    
+    // Step 5 c22x2 = c22*Tadc
+    lt1 = (int)_sic22;
+    lt2 = (int)_uiTadc;
+    lt3 = lt1 * lt2;
+    si_c22x2 = (int)(lt3);
+    
+    // Step 6 a2 = b2 + c22x2
+    lt1 = ((int)_sib2<<15);
+    lt2 = ((int)si_c22x2>1);
+    lt3 = lt1+lt2;
+    si_a2 = ((int)lt3>>16);
+    
+    // Step 7 a1x1 = a1 * Padc
+    lt1 = (int)si_a1;
+    lt2 = (int)_uiPadc;
+    lt3 = lt1*lt2;
+    si_a1x1 = (int)(lt3);
+    
+    // Step 8 y1 = a0 + a1x1
+    lt1 = ((int)_sia0<<10);
+    lt2 = (int)si_a1x1;
+    lt3 = lt1+lt2;
+    si_y1 = ((int)lt3>>10);
+    
+    // Step 9 a2x2 = a2 * Tadc
+    lt1 = (int)si_a2;
+    lt2 = (int)_uiTadc;
+    lt3 = lt1*lt2;
+    si_a2x2 = (int)(lt3);
+    
+    // Step 10 pComp = y1 + a2x2
+    lt1 = ((int)si_y1<<10);
+    lt2 = (int)si_a2x2;
+    lt3 = lt1+lt2;
+    
+    // Fixed point result with rounding
+    siPcomp = ((int)lt3>>13);
+    
+    if(_debug)
+    {       
+        _pc->printf("Success: Calculated Pressure Compesation Value %d\n", siPcomp);
+    }        
+    
+    // decPcomp is defined as a floating point number
+    // Conversion to decimal value from 1023 ADC count value
+    // ADC counts are 0 to 1023, pressure is 50 to 115kPa respectively
+    return (((650.0/1023.0)*siPcomp)+500);
+}
+
+
+/**********************************************************
+ * GetTemperature
+ *  Gets the current temperature from the sensor.
+ *
+ * @return float - The local pressure in °C 
+ **********************************************************/
+float MPL115A2::GetTemperature()
+{
+    return (25 + ((_uiTadc - 498.0) / -5.35));
+}
+
+
+/**********************************************************
+ * Begin
+ *  Gets the coefficients from the sensor.
+ *
+ **********************************************************/
+void MPL115A2::begin()
+{
+    short sia0MSB, sia0LSB;
+    short sib1MSB, sib1LSB;
+    short sib2MSB, sib2LSB;
+    short sic12MSB, sic12LSB;
+    short sic11MSB, sic11LSB;
+    short sic22MSB, sic22LSB;
+    
+    //wakeup
+    _shdnPin=1;
+    _bShutdown = false;
+    wait(0.001); // wait the device to be ready
+
+    //send request for coefficients
+    char cmd[1];
+    cmd[0] = 0x04;
+    _i2c->write(_i2c_address, cmd, 1);
+
+    // read out coefficients
+    char coeff[12];
+    int res = _i2c->read(_i2c_address, coeff, 12);
+    if (res == 0)
+    {
+        sia0MSB = coeff[0];
+        sia0LSB = coeff[1];
+        sib1MSB = coeff[2];
+        sib1LSB = coeff[3];
+        sib2MSB = coeff[4];
+        sib2LSB = coeff[5];
+        sic12MSB = coeff[6];
+        sic12LSB = coeff[7];
+        sic11MSB = coeff[8];
+        sic11LSB = coeff[9];
+        sic22MSB = coeff[10];
+        sic22LSB = coeff[11];
+    
+    
+        // Placing coefficients into 16-bit Variables
+        // a0
+        _sia0 = (signed int) sia0MSB << 8;
+        _sia0 += (signed int) sia0LSB & 0x00FF;
+        // b1
+        _sib1 = (signed int) sib1MSB << 8;
+        _sib1 += (signed int) sib1LSB & 0x00FF;
+        // b2
+        _sib2 = (signed int) sib2MSB << 8;
+        _sib2 += (signed int) sib2LSB & 0x00FF;
+        // c12
+        _sic12 = (signed int) sic12MSB << 8;
+        _sic12 += (signed int) sic12LSB & 0x00FF;
+        // c11
+        _sic11 = (signed int) sic11MSB << 8;
+        _sic11 += (signed int) sic11LSB & 0x00FF;
+        // c22
+        _sic22 = (signed int) sic22MSB << 8;
+        _sic22 += (signed int) sic22LSB & 0x00FF;
+    }
+}
+
+
+void MPL115A2::shutdown()
+{
+    _shdnPin = 0;
+    _bShutdown = true;
+}
\ No newline at end of file