Revision 0:4ea758df868a, committed 2018-12-22

Comitter:

tajiri1999

Date:

Sat Dec 22 16:44:40 2018 +0000

Commit message:

LPS25HB_i2c for mbed

Changed in this revision

diff -r 000000000000 -r 4ea758df868a LPS.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LPS.cpp	Sat Dec 22 16:44:40 2018 +0000
@@ -0,0 +1,212 @@
+#include "LPS.h"
+#include "mbed.h"
+
+// Defines ///////////////////////////////////////////////////////////
+
+// The Arduino two-wire interface uses a 7-bit number for the address,
+#define SA0_LOW_ADDRESS  0b1011100
+#define SA0_HIGH_ADDRESS 0b1011101
+
+#define TEST_REG_NACK -1
+
+#define LPS331AP_WHO_ID 0xBB
+#define LPS25H_WHO_ID   0xBD
+
+// Constructors //////////////////////////////////////////////////////
+
+LPS::LPS(I2C& p_i2c):_i2c(p_i2c)
+{
+    _device = device_auto;
+  
+    // Pololu board pulls SA0 high, so default assumption is that it is
+    // high
+    address = SA0_HIGH_ADDRESS;
+}
+
+// Public Methods ////////////////////////////////////////////////////
+
+// sets or detects device type and slave address; returns bool indicating success
+bool LPS::init(deviceType device, uint8_t sa0)
+{
+    if (!detectDeviceAndAddress(device, (sa0State)sa0))
+        return false;
+    
+    switch (_device)
+    {
+        case device_25H:
+        translated_regs[-INTERRUPT_CFG] = LPS25H_INTERRUPT_CFG;
+        translated_regs[-INT_SOURCE]    = LPS25H_INT_SOURCE;
+        translated_regs[-THS_P_L]       = LPS25H_THS_P_L;
+        translated_regs[-THS_P_H]       = LPS25H_THS_P_H;
+        return true;
+        break;
+      
+        case device_331AP:
+        translated_regs[-INTERRUPT_CFG] = LPS331AP_INTERRUPT_CFG;
+        translated_regs[-INT_SOURCE]    = LPS331AP_INT_SOURCE;
+        translated_regs[-THS_P_L]       = LPS331AP_THS_P_L;
+        translated_regs[-THS_P_H]       = LPS331AP_THS_P_H;
+        return true;
+        break;
+    }
+}
+
+// turns on sensor and enables continuous output
+void LPS::enableDefault(void)
+{
+    if (_device == device_25H)
+    {
+        // 0xB0 = 0b10110000
+        // PD = 1 (active mode);  ODR = 011 (12.5 Hz pressure & temperature output data rate)
+        writeReg(CTRL_REG1, 0xB0);
+    }
+    else if (_device == device_331AP)
+    {
+        // 0xE0 = 0b11100000
+        // PD = 1 (active mode);  ODR = 110 (12.5 Hz pressure & temperature output data rate)
+        writeReg(CTRL_REG1, 0xE0);
+    }
+}
+
+// writes register
+void LPS::writeReg(char reg, char value)
+{
+    // if dummy register address, look up actual translated address (based on device type)
+    if (reg < 0)
+    {
+        reg = translated_regs[-reg];
+    }
+    char command[] = {reg,value};
+    _i2c.write(address << 1,command,2);
+}
+
+// reads register
+int8_t LPS::readReg(char reg)
+{
+    char value;
+    // if dummy register address, look up actual translated address (based on device type)
+    if(reg < 0)
+    {
+        reg = translated_regs[-reg];
+    }
+    _i2c.write(address << 1,&reg,1);
+    _i2c.read((address << 1)|1,&value,1);
+  
+    return value;
+}
+
+// reads pressure in millibars (mbar)/hectopascals (hPa)
+float LPS::readPressureMillibars(void)
+{
+    return (float)readPressureRaw() / 4096;
+}
+
+// reads pressure in inches of mercury (inHg)
+float LPS::readPressureInchesHg(void)
+{
+    return (float)readPressureRaw() / 138706.5;
+}
+
+// reads pressure and returns raw 24-bit sensor output
+int32_t LPS::readPressureRaw(void)
+{
+    // assert MSB to enable register address auto-increment
+  
+    char command = PRESS_OUT_XL | (1 << 7);
+    char p[3];
+    _i2c.write(address << 1,&command,1);
+    _i2c.read((address << 1)| 1,p,3);
+  
+    // combine int8_ts
+    return (int32_t)(int8_t)p[2] << 16 | (uint16_t)p[1] << 8 | p[0];
+}
+
+// reads temperature in degrees C
+float LPS::readTemperatureC(void)
+{
+    return 42.5 + (float)readTemperatureRaw() / 480;
+}
+
+// reads temperature in degrees F
+float LPS::readTemperatureF(void)
+{
+    return 108.5 + (float)readTemperatureRaw() / 480 * 1.8;
+}
+
+// reads temperature and returns raw 16-bit sensor output
+int16_t LPS::readTemperatureRaw(void)
+{
+    char command = TEMP_OUT_L | (1 << 7);
+  
+    // assert MSB to enable register address auto-increment
+    char t[2];
+    _i2c.write(address << 1,&command,1);
+    _i2c.read((address << 1)| 1,t,2);
+
+    // combine bytes
+    return (int16_t)(t[1] << 8 | t[0]);
+}
+
+// converts pressure in mbar to altitude in meters, using 1976 US
+// Standard Atmosphere model (note that this formula only applies to a
+// height of 11 km, or about 36000 ft)
+//  If altimeter setting (QNH, barometric pressure adjusted to sea
+//  level) is given, this function returns an indicated altitude
+//  compensated for actual regional pressure; otherwise, it returns
+//  the pressure altitude above the standard pressure level of 1013.25
+//  mbar or 29.9213 inHg
+float LPS::pressureToAltitudeMeters(double pressure_mbar, double altimeter_setting_mbar)
+{
+    return (1 - pow(pressure_mbar / altimeter_setting_mbar, 0.190263)) * 44330.8;//pressure;
+}
+
+// converts pressure in inHg to altitude in feet; see notes above
+float LPS::pressureToAltitudeFeet(double pressure_inHg, double altimeter_setting_inHg)
+{
+    return (1 - pow(pressure_inHg / altimeter_setting_inHg, 0.190263)) * 145442;//pressure;
+}
+
+// Private Methods ///////////////////////////////////////////////////
+
+bool LPS::detectDeviceAndAddress(deviceType device, sa0State sa0)
+{
+    if (sa0 == sa0_auto || sa0 == sa0_high)
+    {
+        address = SA0_HIGH_ADDRESS;
+        if (detectDevice(device)) return true;
+    }
+    if (sa0 == sa0_auto || sa0 == sa0_low)
+    {
+        address = SA0_LOW_ADDRESS;
+        if (detectDevice(device)) return true;
+    }
+
+    return false;
+}
+
+bool LPS::detectDevice(deviceType device)
+{
+    uint8_t id = testWhoAmI(address);
+  
+    if ((device == device_auto || device == device_25H) && id == (uint8_t)LPS25H_WHO_ID)
+    {
+        _device = device_25H;
+        return true;
+    }
+    if ((device == device_auto || device == device_331AP) && id == (uint8_t)LPS331AP_WHO_ID)
+    {
+        _device = device_331AP;
+        return true;
+    }
+
+    return false;
+}
+
+int LPS::testWhoAmI(uint8_t address)
+{
+    char command = WHO_AM_I;
+    char status = 0;
+    _i2c.write(address << 1,&command,1);
+    _i2c.read((address << 1)| 1,&status,1);
+    return status;
+}
\ No newline at end of file

diff -r 000000000000 -r 4ea758df868a LPS.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LPS.h	Sat Dec 22 16:44:40 2018 +0000
@@ -0,0 +1,111 @@
+#ifndef LPS_h
+#define LPS_h
+
+#include "mbed.h" // for int8_t data type
+
+class LPS
+{
+  public:
+    enum deviceType { device_331AP, device_25H, device_auto };
+    enum sa0State { sa0_low, sa0_high, sa0_auto };
+
+    // register addresses
+    // Note: where register names differ between the register mapping table and
+    // the register descriptions in the datasheets, the names from the register
+    // descriptions are used here.
+    enum regAddr
+    {
+      REF_P_XL                = 0x08,
+      REF_P_L                 = 0x09,
+      REF_P_H                 = 0x0A,
+                              
+      WHO_AM_I                = 0x0F,
+                              
+      RES_CONF                = 0x10,
+                              
+      CTRL_REG1               = 0x20,
+      CTRL_REG2               = 0x21,
+      CTRL_REG3               = 0x22,
+      CTRL_REG4               = 0x23, // 25H
+              
+      STATUS_REG              = 0x27,
+                            
+      PRESS_OUT_XL            = 0x28,
+      PRESS_OUT_L             = 0x29,
+      PRESS_OUT_H             = 0x2A,
+
+      TEMP_OUT_L              = 0x2B,
+      TEMP_OUT_H              = 0x2C,
+      
+      FIFO_CTRL               = 0x2E, // 25H
+      FIFO_STATUS             = 0x2F, // 25H
+      
+      AMP_CTRL                = 0x30, // 331AP
+      
+      RPDS_L                  = 0x39, // 25H
+      RPDS_H                  = 0x3A, // 25H
+      
+      DELTA_PRESS_XL          = 0x3C, // 331AP
+      DELTA_PRESS_L           = 0x3D, // 331AP
+      DELTA_PRESS_H           = 0x3E, // 331AP
+      
+      
+      // dummy addresses for registers in different locations on different devices;
+      // the library translates these based on device type
+      // value with sign flipped is used as index into translated_regs array
+    
+      INTERRUPT_CFG    = -1,
+      INT_SOURCE       = -2,
+      THS_P_L          = -3,
+      THS_P_H          = -4,
+      // update dummy_reg_count if registers are added here!
+      
+      
+      // device-specific register addresses
+      
+      LPS331AP_INTERRUPT_CFG  = 0x23,
+      LPS331AP_INT_SOURCE     = 0x24,
+      LPS331AP_THS_P_L        = 0x25,
+      LPS331AP_THS_P_H        = 0x26,
+      
+      LPS25H_INTERRUPT_CFG    = 0x24,
+      LPS25H_INT_SOURCE       = 0x25,
+      LPS25H_THS_P_L          = 0x30,
+      LPS25H_THS_P_H          = 0x31,
+    };
+
+    LPS(I2C& p_i2c);
+
+    bool init(deviceType device = device_auto,uint8_t sa0 = sa0_auto);
+    deviceType getDeviceType(void) { return _device; }
+    int8_t getAddress(void) { return address; }
+
+    void enableDefault(void);
+
+    void writeReg(char reg, char value);
+    int8_t readReg(char reg);
+
+    float readPressureMillibars(void);
+    float readPressureInchesHg(void);
+    int32_t readPressureRaw(void);
+    float readTemperatureC(void);
+    float readTemperatureF(void);
+    int16_t readTemperatureRaw(void);
+
+    static float pressureToAltitudeMeters(double pressure_mbar, double altimeter_setting_mbar = 1013.25);
+    static float pressureToAltitudeFeet(double pressure_inHg, double altimeter_setting_inHg = 29.9213);
+
+  private:
+    deviceType _device; // chip type (331AP or 25H)
+    I2C &_i2c;
+    uint8_t address;
+    
+    static const int dummy_reg_count = 4;
+    regAddr translated_regs[dummy_reg_count + 1]; // index 0 not used
+
+    bool detectDeviceAndAddress(deviceType device, sa0State sa0);
+    bool detectDevice(deviceType device);
+    int testWhoAmI(uint8_t address);
+};
+
+#endif
\ No newline at end of file

diff -r 000000000000 -r 4ea758df868a sample.txt
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sample.txt	Sat Dec 22 16:44:40 2018 +0000
@@ -0,0 +1,23 @@
+#include "mbed.h"
+#include "LPS.h"
+
+I2C i2c(D14,D15);
+LPS ps(i2c);
+
+int main(){
+    wait_ms(100);
+    if (!ps.init()){
+        printf("Failed to autodetect pressure sensor!\r\n");
+        while (1);
+    }
+    ps.enableDefault();
+    
+    while(1){
+        float pressure = ps.readPressureMillibars();
+        float altitude = ps.pressureToAltitudeMeters(pressure);
+        float temperature = ps.readTemperatureC();
+  
+        printf("p:%.2f\t mbar\ta:%.2f m\tt:%.2f deg C\r\n",pressure,altitude,temperature);
+    }
+    wait_ms(100);
+}
\ No newline at end of file