Diff: LPS331.cpp

Revision:

2:77cb7992a1a3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LPS331.cpp	Thu Jul 24 14:53:59 2014 +0000
@@ -0,0 +1,135 @@
+
+#include <mbed.h>
+#include "LPS331.h"
+
+#define STATUS_REG         0x27
+#define MULTI_BYTE         0x40
+#define REF_P_XL           0x08
+#define REF_P_L            0x09
+#define REF_P_H            0x0A
+#define WHO_AM_I           0x0F
+#define RES_CONF           0x10
+#define CTRL_REG1          0x20
+#define PRESS_POUT_XL_REH  0x28
+#define PRESS_OUT_L        0x29
+#define PRESS_OUT_H        0x2A
+#define TEMP_OUT_L         0x2B
+#define TEMP_OUT_H         0x2C
+
+#define WRITE              0x00
+#define READ               0x80
+
+#define pSensor            0x02
+#define tSensor            0x01
+#define bothSensors        0x03
+
+lps331::lps331(SPI& _spi, PinName _ncs) : spi(_spi), ncs(_ncs) {
+}
+
+uint16_t lps331::read_temperature() {
+    // check if updated value is available
+    if ( ready(tSensor) )
+    {
+        select();
+        // do multi byte read
+        spi.write(READ | MULTI_BYTE | TEMP_OUT_L);
+        uint8_t tempL = spi.write(READ);
+        uint8_t tempH = spi.write(READ);
+        deselect();
+        
+        uint16_t temperature = (tempH<<8) | tempL;
+        // t[C] = 42.5 + temperature /480.0
+        //float temp = (float)(42.5 + ((short)temperature*1.0/480.0));
+        return temperature;
+    }
+    return 0;
+}
+
+uint32_t lps331::read_pressure() {
+    // check if updated value is available
+    if ( ready(pSensor) )
+    {
+        select();
+        // do multi byte read
+        spi.write(READ | MULTI_BYTE | PRESS_POUT_XL_REH);
+        uint8_t pressureLX = spi.write(READ);
+        uint8_t pressureL = spi.write(READ);
+        uint8_t pressureH = spi.write(READ);
+        deselect();
+        
+        uint32_t pressure = (pressureH<<16) | (pressureL<<8) | pressureLX;
+        // P[mBar] = pressure/4096
+        // float P = pressure*1.0/4096.0;
+        return pressure;
+    }
+    return 0;
+}
+
+float lps331::get_Pressure_mbar()
+{
+    uint32_t airP = read_pressure();
+    float pressure = airP*1.0/4096.0;
+    return pressure;
+}
+
+float lps331::get_Temp_C()
+{
+    short airT = read_temperature();
+    float temp = (float)(42.5 + (airT*1.0/480.0));
+    return temp;
+}
+
+float lps331::get_Temp_F()
+{
+    short airT = read_temperature();
+    float temp = (float)(108.5 + (airT*1.8/480.0));
+    return temp;
+}
+
+void lps331::select() {
+    //Set CS low to start transmission (interrupts conversion)
+    ncs = 0;
+}
+
+void lps331::deselect() {
+    //Set CS high to stop transmission (restarts conversion)
+    ncs = 1;
+}
+
+bool lps331::initialize(int setType) {
+    deselect();
+    spi.format(8,0);
+    spi.frequency(400000);  
+    
+    // set chip to update pressure and temp at 25Hz
+    writeRegister(CTRL_REG1, 0xE0);
+    wait_ms(1);
+    
+    // check board is responding
+    int whoami = readRegister(WHO_AM_I);
+    if (whoami == 0xBB)  // addresss of chip
+        return true;
+    return false;
+}
+
+int lps331::ready(uint8_t sensor) {
+    uint8_t status = readRegister(STATUS_REG);
+    if( (status & sensor))
+        return 1;
+    return 0;
+}
+
+uint8_t lps331::readRegister(uint8_t address){
+    select();
+    spi.write(READ | address);
+    uint8_t val = spi.write(READ);
+    deselect();
+    return val;
+    }
+
+void lps331::writeRegister(uint8_t address, uint8_t value){
+     select();
+    spi.write(WRITE | address);
+    spi.write(value);
+    deselect();
+}
\ No newline at end of file