Diff: MPL3115A2.cpp

Revision:

0:beb43bc3d6d4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MPL3115A2.cpp	Tue Apr 01 21:35:23 2014 +0000
@@ -0,0 +1,219 @@
+#include "MPL3115A2.h"
+#include "mbed.h"
+
+#include "stdarg.h" // For debugOut use of the ... parameter and va_list
+
+MPL3115A2::MPL3115A2(I2C *i2c, Serial *pc) : _i2c(i2c), _debug(pc)
+{
+}
+
+// By default I set the sensor to altimeter mode. I inserted a 1ms pause 
+// between each call to allow logic capture if needed. This give a small
+// gap between captures on the bus to make working with the data easier.
+void MPL3115A2::init()
+{
+    setModeStandby();
+    wait_ms(1);
+    setModeAltimeter();
+    wait_ms(1);
+    setOversampleRate(7);
+    wait_ms(1);
+    enableEventFlags();
+    wait_ms(1);
+    setModeActive();
+    wait_ms(1);
+}
+
+// This method wait for a specified amount of time for one of the data
+// ready flags to be set. You need to pass in the correct data ready
+// mask for this to work. See page 22 of the datasheet.
+int MPL3115A2::dataReady(const char mask)
+{
+    int attempts = 0;
+ 
+    while ((i2cRead(STATUS) & mask) == 0)
+    {
+        attempts++;
+        
+        if(attempts > MAX_DATA_READY_ATTEMPTS) 
+            return 0; // Failed
+            
+        wait_ms(1);
+    }
+    
+    return 1; // Success
+}
+
+Altitude* MPL3115A2::readAltitude(Altitude* a)
+{
+    // Force the sensor to take a new reading.
+    toggleOneShot();
+    
+    // Wait for the data to be ready.
+    if (!pressureDataReady())
+    {
+        debugOut("MPL3115A2::readAltitude: Sensor failed to generate an altitude reading in a reasonable time.\r\n");
+        
+        // We leave the altitude object as is if we encounter an error.
+        return a;
+    }
+        
+    // Get the new data from the sensor.
+    _i2c->start();                              // Start
+    if (_i2c->write(MPL3115A2_ADDRESS) != 1)    // A write to device
+        debugOut("MPL3115A2::readAltitude: Sensor failed to respond to write request at address 0x%X\r\n", MPL3115A2_ADDRESS);
+    
+    if (_i2c->write(OUT_P_MSB) != 1)            // Register to read
+        debugOut("MPL3115A2::readAltitude: Sensor at address 0x%X did not acknowledge register 0x%X\r\n", MPL3115A2_ADDRESS, OUT_P_MSB);
+    
+    // Write the data directly into our Altitude object. This object
+    // takes care of converting the compressed data from the sensor, and
+    // provides functions to get the data in various units. And it also
+    // has a print function to output the data as a string.
+    _i2c->read(MPL3115A2_ADDRESS, (*a), Altitude::size);
+    a->setAltitude();
+
+    return a;
+}
+
+// See readAltitude for comments about this function.
+Pressure* MPL3115A2::readPressure(Pressure* p)
+{
+    toggleOneShot();
+    
+    if (!pressureDataReady())
+    {
+        debugOut("MPL3115A2::readPressure: Sensor failed to generate a pressure reading in a reasonable time.\r\n");
+        return p;
+    }
+
+    _i2c->start(); 
+    if (_i2c->write(MPL3115A2_ADDRESS) != 1)
+        debugOut("MPL3115A2::readPressure: Sensor failed to respond to write request at address 0x%X\r\n", MPL3115A2_ADDRESS);
+    
+    if (_i2c->write(OUT_P_MSB) != 1) 
+        debugOut("MPL3115A2::readPressure: Sensor at address 0x%X did not acknowledge register 0x%X\r\n", MPL3115A2_ADDRESS, OUT_P_MSB);
+    
+    _i2c->read(MPL3115A2_ADDRESS, (*p), Pressure::size);
+    p->setPressure();
+
+    return p;
+}
+
+// See readAltitude for comments about this function.
+Temperature* MPL3115A2::readTemperature(Temperature* t)
+{
+    toggleOneShot();
+
+    if (!temperatureDataReady())
+    {
+        debugOut("MPL3115A2::readTemperature: Sensor failed to generate a temperature reading in a reasonable time.\r\n");
+        return t;
+    }
+
+    _i2c->start();  
+    if (_i2c->write(MPL3115A2_ADDRESS) != 1)
+        debugOut("MPL3115A2::readTemperature: Sensor failed to respond to write request at address 0x%X\r\n", MPL3115A2_ADDRESS);
+    
+    if (_i2c->write(OUT_T_MSB) != 1)        
+        debugOut("MPL3115A2::readTemperature: Sensor at address 0x%X did not acknowledge register 0x%X\r\n", MPL3115A2_ADDRESS, OUT_P_MSB);
+    
+    _i2c->read(MPL3115A2_ADDRESS, (*t), Temperature::size);
+    t->setTemperature();
+    
+    return t;
+}
+
+void MPL3115A2::setModeAltimeter()
+{
+    setRegisterBit(CTRL_REG1, 0x80);    // Set ALT bit
+}
+
+void MPL3115A2::setModeBarometer()
+{
+    clearRegisterBit(CTRL_REG1, 0x80);  // Clear ALT bit
+}
+
+void MPL3115A2::setModeStandby()
+{
+    clearRegisterBit(CTRL_REG1, 0x01);  // Clear SBYB bit for Standby mode
+}
+void MPL3115A2::setModeActive()
+{
+    setRegisterBit(CTRL_REG1, 0x01);    // Set SBYB bit for Active mode
+}
+
+void MPL3115A2::setOversampleRate(char sampleRate)
+{
+    if(sampleRate > 7) 
+        sampleRate = 7;                 // OS cannot be larger than 0b.0111
+    
+    sampleRate <<= 3;                   // Align it for the CTRL_REG1 register
+  
+    char temp = i2cRead(CTRL_REG1);     // Read current settings
+    temp &= 0xC7;                       // Clear out old OS bits
+    temp |= sampleRate;                 // Mask in new OS bits
+    i2cWrite(CTRL_REG1, temp);
+}
+
+void MPL3115A2::enableEventFlags()
+{
+    i2cWrite(PT_DATA_CFG, 0x07); // Enable all three pressure and temp event flags 
+}
+
+void MPL3115A2::toggleOneShot(void)
+{
+    clearRegisterBit(CTRL_REG1, 0x02);  // Clear OST bit
+    setRegisterBit(CTRL_REG1, 0x02);    // Set the OST bit.
+}
+
+void MPL3115A2::clearRegisterBit(const char regAddr, const char bitMask)
+{
+    char temp = i2cRead(regAddr);   // Read the current register value
+    temp &= ~bitMask;               // Clear the bit from the value
+    i2cWrite(regAddr, temp);        // Write register value back
+}
+
+void MPL3115A2::setRegisterBit(const char regAddr, const char bitMask)
+{
+    char temp = i2cRead(regAddr);   // Read the current register value
+    temp |= bitMask;                // Set the bit in the value
+    i2cWrite(regAddr, temp);        // Write register value back
+}
+
+char MPL3115A2::i2cRead(char regAddr)
+{
+    _i2c->start();                              // Start
+    if (_i2c->write(MPL3115A2_ADDRESS)!=1)      // A write to device
+        debugOut("MPL3115A2::i2cRead: Sensor failed to respond to write request at address 0x%X\r\n", MPL3115A2_ADDRESS);
+    
+    if (_i2c->write(regAddr)!=1)                // Register to read
+        debugOut("MPL3115A2::i2cRead: Sensor at address 0x%X did not acknowledge register 0x%X\r\n", MPL3115A2_ADDRESS, regAddr);
+    
+    _i2c->start();                  
+    if (_i2c->write(MPL3115A2_ADDRESS|0x01)!=1) // Read from device
+        debugOut("MPL3115A2::i2cRead: Sensor failed to respond to read request at address 0x%X\r\n", MPL3115A2_ADDRESS);
+
+    char result = _i2c->read(READ_NAK);         // Read the data
+    _i2c->stop();
+    
+    return result;  
+}
+
+void MPL3115A2::i2cWrite(char regAddr, char value)
+{
+    char cmd[2];
+    cmd[0] = regAddr;
+    cmd[1] = value;
+    if (_i2c->write(MPL3115A2_ADDRESS, cmd, 2) != 0)
+        debugOut("MPL3115A2::i2cWrite: Failed writing value (%d, 0x%X) to register 0x%X\r\n", value, regAddr);    
+}
+
+void MPL3115A2::debugOut(const char * format, ...)
+{
+    if (_debug == NULL)
+        return;
+        
+    va_list arg;
+    _debug->printf(format, arg);
+}