Diff: ms5637.cpp

Revision:

8:3a9d37268ccd

Parent:

7:2e8bc98f3dda

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ms5637.cpp	Tue May 20 16:18:00 2014 +0000
@@ -0,0 +1,355 @@
+//!
+//! @file an520_I2C.c,v
+//!
+//! Copyright (c) 2009 MEAS Switzerland
+//!
+//!
+//!
+//! @brief This C code is for starter reference only. It is written for the
+//! MEAS Switzerland MS56xx pressure sensor modules and Atmel Atmega644p
+//! microcontroller.
+//!
+//! @version 1.0 $Id: an520_I2C.c,v 1.0
+//!
+//! @todo
+
+#include "mbed.h"
+#include "ms5637.h"
+
+double P;                       // compensated pressure value (mB)
+double T;                       // compensated temperature value (degC)
+double A;                       // altitude (ft)
+double S;                       // sea level barometer (mB)
+
+uint32_t C[8];                  //coefficient storage
+
+//--------------------------------------------------------------------------------------------------------------------------------------//
+// Constructor and destructor
+
+ms5637::ms5637(PinName sda, PinName scl)  : _i2c(sda, scl) {
+        _i2c.frequency(400000);
+}
+
+//********************************************************
+//! @brief send I2C start condition and the address byte
+//!
+//! @return 0
+//********************************************************
+
+int ms5637::m_i2c_start(bool readMode) {
+    int twst;
+    _i2c.start();
+    if(readMode == true) {
+        twst = m_i2c_write(MS5637_ADDR_R);
+    } else {
+        twst = m_i2c_write(MS5637_ADDR_W);
+    }
+    return(twst);
+}
+
+//********************************************************
+//! @brief send I2C stop condition
+//!
+//! @return none
+//********************************************************
+
+void ms5637::m_i2c_stop(void) {
+    _i2c.stop();
+}
+
+//********************************************************
+//! @brief send I2C stop condition
+//!
+//! @return remote ack status
+//********************************************************
+
+unsigned char ms5637::m_i2c_write(unsigned char data) {
+    int twst = _i2c.write(data);
+    return(twst);
+}
+
+//********************************************************
+//! @brief read I2C byte with acknowledgment
+//!
+//! @return read byte
+//********************************************************
+
+unsigned char ms5637::m_i2c_readAck(void) {
+    int twst = _i2c.read(1);
+    return(twst);
+}
+
+//********************************************************
+//! @brief read I2C byte without acknowledgment
+//!
+//! @return read byte
+//********************************************************
+
+unsigned char ms5637::m_i2c_readNak(void) {
+    int twst = _i2c.read(0);
+    return(twst);
+}
+
+//********************************************************
+//! @brief send command using I2C hardware interface
+//!
+//! @return none
+//********************************************************
+
+void ms5637::m_i2c_send(char cmd) {
+    unsigned char ret;
+    ret = m_i2c_start(false);
+    if(!(ret)) {
+        m_i2c_stop();
+    } else {
+        ret = m_i2c_write(cmd);
+        m_i2c_stop();
+    }
+}
+
+//********************************************************
+//! @brief send reset sequence
+//!
+//! @return none
+//********************************************************
+
+void ms5637::cmd_reset() {
+    m_i2c_send(MS5637_CMD_RESET);
+    wait_ms(4);
+    loadCoefs();
+}
+
+//********************************************************
+//! @brief preform adc conversion
+//!
+//! @return 24bit result
+//********************************************************
+
+unsigned long ms5637::cmd_adc(char cmd) {
+    char cobuf[3];
+    cobuf[0] = 0;
+    cobuf[1] = 0;
+    cobuf[2] = 0;
+    unsigned int ret;
+    unsigned long temp = 0;
+    m_i2c_send(MS5637_CMD_ADC_CONV + cmd);
+    switch (cmd & 0x0f) {
+        case MS5637_CMD_ADC_256 : wait_us(900); break;
+        case MS5637_CMD_ADC_512 : wait_ms(3); break;
+        case MS5637_CMD_ADC_1024: wait_ms(4); break;
+        case MS5637_CMD_ADC_2048: wait_ms(6); break;
+        case MS5637_CMD_ADC_4096: wait_ms(10); break;
+    }
+    m_i2c_send(MS5637_CMD_ADC_READ);
+    
+    ret = _i2c.read(MS5637_ADDR_R, cobuf, 3, false);
+    if(ret) printf("\n*** ms5637 ADC Read Error ");
+    temp = (cobuf[0] << 16) + (cobuf[1] << 8) + cobuf[2];
+    return temp;
+}
+
+//********************************************************
+//! @brief Read calibration coefficients
+//!
+//! @return coefficient
+//********************************************************
+
+unsigned int ms5637::cmd_prom(char coef_num) {
+    char cobuf[2];
+    unsigned int ret;
+    unsigned int rC = 0;
+    cobuf[0] = 0;
+    cobuf[1] = 0;
+    m_i2c_send(MS5637_CMD_PROM_RD + coef_num * 2); // send PROM READ command
+    ret = _i2c.read(MS5637_ADDR_R, cobuf, 2, false);
+    if(ret) printf("\n*** ms5637 PROM Read Error ");
+    rC = cobuf[0] * 256 + cobuf[1];
+    return rC;
+}
+
+//********************************************************
+//! @brief calculate the CRC code
+//!
+//! @return crc code
+//********************************************************
+
+unsigned char ms5637::crc4(unsigned int n_prom[]) {
+    unsigned int n_rem;
+    unsigned int crc_read;
+    unsigned char n_bit;
+    n_rem = 0x00;
+    crc_read = n_prom[7];
+    n_prom[7]=(0xFF00 & (n_prom[7]));
+    for (int cnt = 0; cnt < 16; cnt++) {
+            if (cnt%2 == 1) {
+                n_rem ^= (unsigned short) ((n_prom[cnt>>1]) & 0x00FF);
+            } else {
+                n_rem ^= (unsigned short) (n_prom[cnt>>1]>>8);
+            }
+            for (n_bit = 8; n_bit > 0; n_bit--) {
+                if (n_rem & (0x8000)) {
+                    n_rem = (n_rem << 1) ^ 0x3000;
+                } else {
+                    n_rem = (n_rem << 1);
+                }
+            }
+        }
+    n_rem= (0x000F & (n_rem >> 12));
+    n_prom[7]=crc_read;
+    return (n_rem ^ 0x0);
+}
+
+/*
+The CRC code is calculated and written in factory with the LSB byte in the prom n_prom[7] set to 0x00 (see
+Coefficient table below). It is thus important to clear those bytes from the calculation buffer before proceeding
+with the CRC calculation itself:
+n_prom[7]=(0xFF00 & (n_prom[7])); //CRC byte is replaced by 0
+As a simple test of the CRC code, the following coefficient table could be used:
+unsigned int nprom[] = {0x3132,0x3334,0x3536,0x3738,0x3940,0x4142,0x4344,0x4500};
+the resulting calculated CRC should be 0xB.
+
+DB  15  14  13  12  11  10  9   8   7   6   5   4   3   2   1   0 
+Addr
+0               16 bit reserved for manufacturer
+1               Coefficient 1 (16 bit unsigned)
+2               Coefficient 2 (16 bit unsigned)
+3               Coefficient 3 (16 bit unsigned)
+4               Coefficient 4 (16 bit unsigned)
+5               Coefficient 5 (16 bit unsigned)
+6               Coefficient 6 (16 bit unsigned)
+7                                   0   0   0   0     CRC(0x0)
+*/    
+/*   
+    //Returns 0x0b as per AP520_004 
+    C[0] = 0x3132;
+    C[1] = 0x3334;
+    C[2] = 0x3536;
+    C[3] = 0x3738;
+    C[4] = 0x3940;
+    C[5] = 0x4142;
+    C[6] = 0x4344;
+    C[7] = 0x4546;
+    n_crc = ms.crc4(C); // calculate the CRC
+    pc.printf("testing CRC: 0x%x\n", n_crc);
+*/
+
+//********************************************************
+//! @brief load all calibration coefficients
+//!
+//! @return none
+//********************************************************
+
+void ms5637::loadCoefs() {
+    for (int i = 0; i < 8; i++){ 
+        wait_ms(50);
+        C[i] = cmd_prom(i);
+    }
+    unsigned char n_crc = crc4(C);
+}
+
+//********************************************************
+//! @brief calculate temperature and pressure
+//!
+//! @return none
+//********************************************************   
+     
+void ms5637::calcPT() {
+    int32_t D2 = cmd_adc(MS5637_CMD_ADC_D2 + MS5637_CMD_ADC_4096); // read D2
+    int32_t D1 = cmd_adc(MS5637_CMD_ADC_D1 + MS5637_CMD_ADC_4096); // read D1
+    int64_t dT = D2 - ((uint64_t)C[5] << 8);
+    int64_t OFF  = ((uint32_t)C[2] << 17) + ((dT * (C[4]) >> 6));     //was  OFF  = (C[2] << 17) + dT * C[4] / (1 << 6);
+    int64_t SENS = ((uint32_t)C[1] << 16) + ((dT * (C[3]) >> 7));     //was  SENS = (C[1] << 16) + dT * C[3] / (1 << 7);
+    //T = (2000 + (((uint64_t)dT * C[6]) / (float)(1 << 23))) / 100;
+    T=(2000+(dT*C[6])/8388608)/100;
+    //int32_t TEMP = 2000 + (int64_t)dT * (int64_t)C[6] / (int64_t)(1 << 23);
+    int32_t TEMP = 2000 + (int64_t)dT * (int64_t)(C[6] >> 23);
+    if(TEMP < 2000) { // if temperature lower than 20 Celsius
+        float T1 = (TEMP - 2000) * (TEMP - 2000);
+        int64_t OFF1  = (61 * T1) / 16;
+        int64_t SENS1 = (29 * T1) / 16;
+
+        if(TEMP < -1500) { // if temperature lower than -15 Celsius
+            T1 = (TEMP + 1500) * (TEMP + 1500);
+            OFF1  += 17 * T1;
+            SENS1 += 9 * T1 ;
+        } 
+        OFF -= OFF1;
+        SENS -= SENS1;
+        T = (float)TEMP / 100; 
+    }
+//    int64_t P1 = ((((int64_t)D1 * SENS) >> 21) - OFF) >> 15;   
+    //P = ((((int64_t)D1 * SENS ) >> 21) - OFF) / (double) (1 << 15) / 100.0;
+    P=(D1*SENS/2097152-OFF)/3276800;
+}
+
+//********************************************************
+//! @brief calculate temperature
+//!
+//! @return double temperature degC
+//********************************************************  
+
+double ms5637::calcTemp() {
+    calcPT();
+    return(T);
+} 
+
+//********************************************************
+//! @brief calculate pressure
+//!
+//! @return double barometric pressure millibar
+//********************************************************  
+
+double ms5637::calcPressure() {
+    calcPT();
+    return(P);
+} 
+
+//********************************************************
+//! @brief get pressure, no calculation
+//!
+//! @return double barometric pressure millibar
+//********************************************************  
+
+double ms5637::getPressure() {
+    calcPT();
+    return(P);
+} 
+
+//********************************************************
+//! @brief get altitude from known sea level barometer, 
+//! @      no pre-pressure calculation
+//!
+//! @enter float sea level barometer
+//! @return float altitude in feet
+//********************************************************  
+
+float ms5637::getAltitudeFT(float sea_pressure) {
+    A = (1 - (pow((P / (double)sea_pressure), 0.190284))) * 145366.45;
+    return((float)A);
+} 
+
+//********************************************************
+//! @brief get sea level pressure from known altitude(ft), 
+//! @      no pre-pressure calculation
+//!
+//! @enter float known altitude in feet
+//! @return float seal level barometer in mb
+//********************************************************  
+
+float ms5637::getSeaLevelBaroFT(float known_alt) {
+    S = pow(pow((P * INHG), 0.190284) + 0.00001313 * known_alt , 5.2553026) * MB;
+    return((float)S);
+} 
+
+//********************************************************
+//! @brief get sea level pressure from known altitude(m), 
+//! @      no pre-pressure calculation
+//!
+//! @enter float known altitude in meters
+//! @return float seal level barometer in mb
+//********************************************************  
+
+float ms5637::getSeaLevelBaroM(float known_alt) {
+    S = pow(pow((P * INHG), 0.190284) + 0.00001313 * known_alt * FTMETERS , 5.2553026) * MB;
+    return((float)S);
+}