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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MPL3115A2.h Tue Apr 01 21:35:23 2014 +0000 @@ -0,0 +1,172 @@ +/* + MPL3115A2 Barometric Pressure and Tempurature Sensor Library + By: Michael Lange + Date: March 31, 2014 + License: This code is public domain. + + This class wraps the functions of the MPL3115A2 sensor into + a usable class that exposes most functions to your project. + Functions that are not exposed can easily be added using the + existing functions in this library. Specifically, I did not + add any funtions to handle FIFO logging or the use of either + of the pin interrupts. This should not be too difficult to + add if you need those features. + + The motivation here was to get a set of support classes + together that supported the chip and could be expanded on. + With this library you can extract all relevant data from the + sensor. + + Be sure to download the DATASHEET and the App Note AN4519. + + This libraray was created using the mbed NXP LPC11U24. Pins + p27 and p28 were used for the I2C functions. Be sure to install + 1K pull-up resistors on both lines. Also, if you're not using + the SparkFun breakout board, be sure to use the right caps on + the power pin. If you don't, the jitter can cause problems. + + This library was inspired by the similar library available for + the Arduino written by Nathan Seidle at SparkFun. I copied + some of the number crunching routines and tried to follow his + style of coding for the library. That way users of Arduinos + cound step into this library a little easier. + + */ + + +#ifndef MPL3115A2_H +#define MPL3115A2_H + +#include "mbed.h" + +#include "Altitude.h" // Our classes to handle compressed data from the sensor. +#include "Temperature.h" +#include "Pressure.h" + +#define MPL3115A2_ADDRESS 0xC0 // Shifted 7-bit I2C address for sensor + +#define READ_ACK 1 // For mbed I2C Read method. +#define READ_NAK 0 + +#define MAX_DATA_READY_ATTEMPTS 512 // How many times we loop waiting for data before giving up. + +// DEFINE |REGISTER |RESET |RESET |TYPE |AUTO-INC |NAME/COMMENT +// | | |STBY2ACT | |ADDRESS | +#define STATUS 0x00 // | 0x00 | Yes | R | 0x01 | Sensor Status Register (Alias for DR_STATUS or F_STATUS) +#define OUT_P_MSB 0x01 // | 0x00 | Yes | R | 0x02 | 0x01 | Pressure Data Out MSB (Bits 12-19 of 20-bit real-time Pressure sample | Root pointer t oPressure and Tempurature FIFO data) +#define OUT_P_CSB 0x02 // | 0x00 | Yes | R | 0x03 | Pressure Data out CSB (Bits 0-3 of 20-bit real-time Pressure sample) +#define OUT_P_LSB 0x03 // | 0x00 | | | 0x | +#define OUT_T_MSB 0x04 // | 0x00 | | | 0x | +#define OUT_T_LSB 0x05 // | 0x00 | | | 0x | +#define DR_STATUS 0x06 // | 0x00 | | | 0x | +#define OUT_P_DELTA_MSB 0x07 // | 0x00 | | | 0x | +#define OUT_P_DELTA_CSB 0x08 // | 0x00 | | | 0x | +#define OUT_P_DELTA_LSB 0x09 // | 0x00 | | | 0x | +#define OUT_T_DELTA_MSB 0x0A // | 0x00 | | | 0x | +#define OUT_T_DELTA_LSB 0x0B // | 0x00 | | | 0x | +#define WHO_AM_I 0x0C // | 0xC4 | | | 0x | +#define F_STATUS 0x0D // | 0x00 | | | 0x | +#define F_DATA 0x0E // | 0x00 | | | 0x | +#define F_SETUP 0x0F // | 0x00 | | | 0x | +#define TIME_DLY 0x10 // | 0x00 | | | 0x | +#define SYSMOD 0x11 // | 0x00 | | | 0x | +#define INT_SOURCE 0x12 // | 0x00 | | | 0x | +#define PT_DATA_CFG 0x13 // | 0x00 | | | 0x | +#define BAR_IN_MSB 0x14 // | 0xC5 | | | 0x | +#define BAR_IN_LSB 0x15 // | 0xE7 | | | 0x | +#define P_TGT_MSB 0x16 // | 0x00 | | | 0x | +#define P_TGT_LSB 0x17 // | 0x00 | | | 0x | +#define T_TGT 0x18 // | 0x00 | | | 0x | +#define P_WND_MSB 0x19 // | 0x00 | | | 0x | +#define P_WND_LSB 0x1A // | 0x00 | | | 0x | +#define T_WND 0x1B // | 0x00 | | | 0x | +#define P_MIN_MSB 0x1C // | 0x00 | | | 0x | +#define P_MIN_CSB 0x1D // | 0x00 | | | 0x | +#define P_MIN_LSB 0x1E // | 0x00 | | | 0x | +#define T_MIN_MSB 0x1F // | 0x00 | | | 0x | +#define T_MIN_LSB 0x20 // | 0x00 | | | 0x | +#define P_MAX_MSB 0x21 // | 0x00 | | | 0x | +#define P_MAX_CSB 0x22 // | 0x00 | | | 0x | +#define P_MAX_LSB 0x23 // | 0x00 | | | 0x | +#define T_MAX_MSB 0x24 // | 0x00 | | | 0x | +#define T_MAX_LSB 0x25 // | 0x00 | | | 0x | +#define CTRL_REG1 0x26 // | 0x00 | | | 0x | +#define CTRL_REG2 0x27 // | 0x00 | | | 0x | +#define CTRL_REG3 0x28 // | 0x00 | | | 0x | +#define CTRL_REG4 0x29 // | 0x00 | | | 0x | +#define CTRL_REG5 0x2A // | 0x00 | | | 0x | +#define OFF_P 0x2B // | 0x00 | | | 0x | +#define OFF_T 0x2C // | 0x00 | | | 0x | +#define OFF_H 0x2D // | 0x00 | | | 0x | + +class MPL3115A2 +{ +public: + MPL3115A2(I2C *i2c, Serial *pc = NULL); + + // Call this method in main to initialize the sensor. + void init(); + + // Returns the fixed device ID number (usually equal to 0xC4). + char whoAmI() { return i2cRead(WHO_AM_I); } + + Altitude* readAltitude(Altitude* a); // Returns the altitude object with altitude + Pressure* readPressure(Pressure* p); // Returns the pressure object with barometric pressure + Temperature* readTemperature(Temperature* t); // Returns the temperature object with temperature + + // Use these methods to set the sensor's offsets to increase its accuracy. You can generally + // find your current altitude with a smart phone or GPS. Same goes for the temperature. For + // the current pressure where you are, you may need an accurate weather station. Getting the + // pressure from the web for your area is generally not close enough to help with calibration. + // You may need to play with the setting to achieve good accuracy. I found the offset steps + // were not 100% accurate to the datasheet and had to adjust accordingly. + char offsetAltitude() { return i2cRead(OFF_H); } + void setOffsetAltitude(const char offset) { i2cWrite(OFF_H, offset); } // -128 to 127 meters + char offsetPressure() { return i2cRead(OFF_P); } + void setOffsetPressure(const char offset) { i2cWrite(OFF_P, offset); } // 4 Pa per LSB + char offsetTemperature() { return i2cRead(OFF_T); } + void setOffsetTemperature(const char offset) { i2cWrite(OFF_T, offset); } // 0.0625ºC per LSB + + void setModeStandby(); // Puts the sensor into Standby mode. Required when using methods below. + void setModeActive(); // Activates the sensor to start taking measurements. + + // When calling any of these methods, be sure to put the sensor in standby mode first. + void setModeBarometer(); // Puts the sensor into barometric mode + void setModeAltimeter(); // Puts the sensor into altimeter mode + void setOversampleRate(char); // Sets the number of samples from 1 to 128. + void enableEventFlags(); // Sets the all event flags. + +private: + I2C *_i2c; // The I2C object we use to communicate with the sensor. It is not part + // of the class so that it can be shared with other peripherals on the + // bus. + Serial *_debug; // Set this in the constructor if you want the class to output debug messages. + // If you need to pair down your code, you can remove this and all the + // references to it in the code. + + // Debug method that mimics the printf function, but will output nothing if _debug has not + // been set. This means you can safely us it in your code and nothing will happen if you don't + // assign the _debug object. + void debugOut(const char * format, ...); + + // These are helper functions to SET or CLEAR bits. The mask should contain 1s in the position + // where the bits need to be set or cleared. One or more bits can be set or cleared this way. + void clearRegisterBit(const char regAddr, const char bitMask); + void setRegisterBit(const char regAddr, const char bitMask); + + // Helper functions to check if data is ready in a register for either temperature or pressure. + // The pressureDataReady function works for both altitude and barometric pressure depending on + // the mode the sensor is in. + int dataReady(const char mask); + int pressureDataReady() { return dataReady(0x04); } + int temperatureDataReady() { return dataReady(0x02); } + + // Called to force the sensor to take another sample + void toggleOneShot(); + + // Helper functions to read and write one value from the I2C bus using the sensor's address. + char i2cRead(char regAddr); + void i2cWrite(char regAddr, char value); +}; + +#endif // MPL3115A2_H