MS5837.cpp

00001 #include <stdlib.h>
00002 #include "MS5837.h"
00003 
00004 
00005 /*
00006  * Sensor operating function according data sheet
00007  */
00008 
00009 void MS5837::MS5837Init(void)
00010 {
00011     MS5837Reset();
00012     MS5837ReadProm();
00013     return;
00014 }
00015 
00016 /* Send soft reset to the sensor */
00017 void MS5837::MS5837Reset(void)
00018 {
00019     /* transmit out 1 byte reset command */
00020     ms5837_tx_data[0] = ms5837_reset;
00021     if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
00022     //printf("send soft reset\n\r");
00023     wait_ms(20);
00024 }
00025 
00026 /* read the sensor calibration data from rom */
00027 void MS5837::MS5837ReadProm(void)
00028 {
00029     uint8_t i,j;
00030     for (i=0; i<8; i++) {
00031         j = i;
00032         ms5837_tx_data[0] = ms5837_PROMread + (j<<1);
00033         if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
00034         if ( i2c.read( device_address,  ms5837_rx_data, 2 ) );
00035         C[i]   = ms5837_rx_data[1] + (ms5837_rx_data[0]<<8);
00036     }
00037 }
00038 
00039 /* Start the sensor pressure conversion */
00040 void MS5837::MS5837ConvertD1(void)
00041 {
00042     ms5837_tx_data[0] = ms5837_convD1;
00043     if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
00044 }
00045 
00046 /* Start the sensor temperature conversion */
00047 void MS5837:: MS5837ConvertD2(void)
00048 {
00049     ms5837_tx_data[0] = ms5837_convD2;
00050     if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
00051 }
00052 
00053 /* Read the previous started conversion results */
00054 int32_t MS5837::MS5837ReadADC(void)
00055 {
00056     int32_t adc;
00057     wait_ms(150);
00058     ms5837_tx_data[0] = ms5837_ADCread;
00059     if ( i2c.write( device_address,  ms5837_tx_data, 1 ) );
00060     if ( i2c.read( device_address,  ms5837_rx_data, 3 ) );
00061     adc = ms5837_rx_data[2] + (ms5837_rx_data[1]<<8) + (ms5837_rx_data[0]<<16);
00062     //printf("ADC value: %x\n", adc);
00063     return (adc);
00064 }
00065 
00066 /* return the results */
00067 float MS5837::MS5837_Pressure (void)
00068 {
00069     return P_MS5837;
00070 }
00071 float MS5837::MS5837_Temperature (void)
00072 {
00073     return T_MS5837;
00074 }
00075 
00076 /* Sensor reading and calculation procedure */
00077 void MS5837::Barometer_MS5837(void)
00078 {
00079     int32_t dT, temp;
00080     int64_t OFF, SENS, press;
00081 
00082     //no need to do this everytime!
00083     
00084     
00085     MS5837ConvertD1();             // start pressure conversion
00086     D1 = MS5837ReadADC();        // read the pressure value
00087     MS5837ConvertD2();             // start temperature conversion
00088     D2 = MS5837ReadADC();         // read the temperature value
00089     //printf("D1 = %d\n", D1);
00090     /* calculation according MS5837-01BA data sheet DA5837-01BA_006 */
00091     dT       = D2 - (C[5]* 256);
00092     OFF      = (int64_t)C[2] * (1<<16) + ((int64_t)dT * (int64_t)C[4]) / (1<<7);
00093     SENS     = (int64_t)C[1] * (1<<15) + ((int64_t)dT * (int64_t)C[3]) / (1<<8);
00094 
00095     temp     = 2000 + (dT * C[6]) / (1<<23);
00096     T_MS5837 = (float) temp / 100.0f;                 // result of temperature in deg C in this var
00097     press    = (((int64_t)D1 * SENS) / (1<<21) - OFF) / (1<<13);
00098     P_MS5837 = (float) press / 10.0f;                 // result of pressure in mBar in this var
00099     
00100     if (P_MS5837 < 900 || P_MS5837 > 3000) {
00101         MS5837Reset();                 // reset the sensor
00102         MS5837ReadProm();             // read the calibration values
00103     }
00104 }
00105 
00106 float MS5837::get_depth_initial(void){
00107     depth_iter = 0;
00108     Depth_0 = 0;
00109     for(int i = 0; i < 5; i++){
00110         Barometer_MS5837();
00111         depth_iter = ((P_MS5837)*1.019716);
00112         Depth_0 = depth_iter + Depth_0;
00113     }
00114     Depth_0 = Depth_0/5;
00115     if(Depth_0 < 1000 || Depth_0 > 1100){
00116         MS5837Init();
00117         get_depth_initial();
00118     }
00119     return Depth_0;
00120 }
00121 
00122 float MS5837::get_depth(void) {
00123     depth_iter = 0;
00124     depth = 0;
00125     for(int i = 0; i <= 2; i++){
00126         Barometer_MS5837();
00127         depth_iter = ((P_MS5837)*1.019716)-Depth_0;
00128         depth = depth_iter + depth;
00129     }
00130     depth = depth/3;
00131     return depth;
00132 }