Diff: MS5837/MS5837.cpp

Revision:

0:f8bc804eadbc

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MS5837/MS5837.cpp	Sun Mar 20 03:05:25 2016 +0000
@@ -0,0 +1,100 @@
+#include <stdlib.h>
+#include "MS5837.h"
+
+
+/*
+ * Sensor operating function according data sheet
+ */
+
+void MS5837::MS5837Init(void)
+{
+    MS5837Reset();
+    MS5837ReadProm();
+    return;
+}
+
+/* Send soft reset to the sensor */
+void MS5837::MS5837Reset(void)
+{
+    /* transmit out 1 byte reset command */
+    ms5837_tx_data[0] = ms5837_reset;
+    if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
+    //printf("send soft reset");
+    wait_ms(20);
+}
+
+/* read the sensor calibration data from rom */
+void MS5837::MS5837ReadProm(void)
+{
+    uint8_t i,j;
+    for (i=0; i<8; i++) {
+        j = i;
+        ms5837_tx_data[0] = ms5837_PROMread + (j<<1);
+        if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
+        if ( i2c.read( device_address,  ms5837_rx_data, 2 ) );
+        C[i]   = ms5837_rx_data[1] + (ms5837_rx_data[0]<<8);
+    }
+}
+
+/* Start the sensor pressure conversion */
+void MS5837::MS5837ConvertD1(void)
+{
+    ms5837_tx_data[0] = ms5837_convD1;
+    if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
+}
+
+/* Start the sensor temperature conversion */
+void MS5837:: MS5837ConvertD2(void)
+{
+    ms5837_tx_data[0] = ms5837_convD2;
+    if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
+}
+
+/* Read the previous started conversion results */
+int32_t MS5837::MS5837ReadADC(void)
+{
+    int32_t adc;
+    wait_ms(150);
+    ms5837_tx_data[0] = ms5837_ADCread;
+    if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
+    if ( i2c.read( device_address,  ms5837_rx_data, 3 ) );
+    adc = ms5837_rx_data[2] + (ms5837_rx_data[1]<<8) + (ms5837_rx_data[0]<<16);
+    return (adc);
+}
+
+/* return the results */
+float MS5837::MS5837_Pressure (void)
+{
+    return P_MS5837;
+}
+float MS5837::MS5837_Temperature (void)
+{
+    return T_MS5837;
+}
+
+/* Sensor reading and calculation procedure */
+void MS5837::Barometer_MS5837(void)
+{
+    int32_t dT, temp;
+    int64_t OFF, SENS, press;
+
+    //no need to do this everytime!
+    //MS5837Reset();                 // reset the sensor
+    //MS5837ReadProm();             // read the calibration values
+    
+    
+    MS5837ConvertD1();             // start pressure conversion
+    D1 = MS5837ReadADC();        // read the pressure value
+    MS5837ConvertD2();             // start temperature conversion
+    D2 = MS5837ReadADC();         // read the temperature value
+
+    /* calculation according MS5837-01BA data sheet DA5837-01BA_006 */
+    dT       = D2 - (C[5]* 256);
+    OFF      = (int64_t)C[2] * (1<<16) + ((int64_t)dT * (int64_t)C[4]) / (1<<7);
+    SENS     = (int64_t)C[1] * (1<<15) + ((int64_t)dT * (int64_t)C[3]) / (1<<8);
+
+    temp     = 2000 + (dT * C[6]) / (1<<23);
+    T_MS5837 = (float) temp / 100.0f;                 // result of temperature in deg C in this var
+    press    = (((int64_t)D1 * SENS) / (1<<21) - OFF) / (1<<13);
+    P_MS5837 = (float) press / 10.0f;                 // result of pressure in mBar in this var
+}