BMP180 Device Driver

Revision 0:b2219e6e444b, committed 2015-04-17

Comitter:

kgills

Date:

Fri Apr 17 09:31:09 2015 -0500

Commit message:

Adding BMP180 library files.

Changed in this revision

diff -r 000000000000 -r b2219e6e444b BMP180.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP180.cpp	Fri Apr 17 09:31:09 2015 -0500
@@ -0,0 +1,268 @@
+/*******************************************************************************
+ * Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
+ * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Except as contained in this notice, the name of Maxim Integrated
+ * Products, Inc. shall not be used except as stated in the Maxim Integrated
+ * Products, Inc. Branding Policy.
+ *
+ * The mere transfer of this software does not imply any licenses
+ * of trade secrets, proprietary technology, copyrights, patents,
+ * trademarks, maskwork rights, or any other form of intellectual
+ * property whatsoever. Maxim Integrated Products, Inc. retains all
+ * ownership rights.
+ *******************************************************************************
+ */
+
+#include "BMP180.h"
+
+/***** Definitions *****/
+#define I2C_ADDR            (0xEE) // 1110111x
+
+#define REG_ADDR_RESET      (0xE0)
+#define REG_ADDR_ID         (0xD0)
+#define REG_ADDR_CTRL       (0xF4)
+#define REG_ADDR_DATA       (0xF6)
+#define REG_ADDR_AC1        (0xAA)
+
+#define CTRL_REG_TEMP       (0x2E)
+#define CTRL_REG_PRESS_0    (0x34)
+#define CTRL_REG_PRESS_1    (0x74)
+#define CTRL_REG_PRESS_2    (0xB4)
+#define CTRL_REG_PRESS_3    (0xF4)
+
+//******************************************************************************
+BMP180::BMP180(PinName sda, PinName scl)
+{
+    i2c_ = new I2C(sda, scl);
+    i2c_owner = true;
+
+    i2c_->frequency(400000);
+}
+
+//******************************************************************************
+BMP180::BMP180(I2C *i2c) :
+    i2c_(i2c)
+{
+    i2c_owner = false;
+}
+
+//******************************************************************************
+BMP180::~BMP180()
+{
+    if(i2c_owner) {
+        delete i2c_;
+    }
+}
+
+//******************************************************************************
+int BMP180::init(void)
+{
+    char addr;
+    char data[22];
+    int i;
+
+    if (checkId() != 0) {
+        return -1;
+    }
+
+    addr = REG_ADDR_AC1;
+    if (i2c_->write(I2C_ADDR, &addr, 1) != 0) {
+        return -1;
+    }
+
+    if (i2c_->read(I2C_ADDR, data, 22) != 0) {
+        return -1;
+    }
+
+    for (i = 0; i < 11; i++) {
+        calib.value[i] = (data[2*i] << 8) | data[(2*i)+1];
+    }
+
+    return 0;
+}
+
+//******************************************************************************
+int BMP180::reset(void)
+{
+    char data;
+
+    data = REG_ADDR_RESET;
+    if (i2c_->write(I2C_ADDR, &data, 1) != 0) {
+        return -1;
+    }
+
+    data = 0xB6;
+    if (i2c_->write(I2C_ADDR, &data, 1) != 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+//******************************************************************************
+int BMP180::checkId(void)
+{
+    char addr;
+    char data;
+
+    addr = REG_ADDR_ID;
+    if (i2c_->write(I2C_ADDR, &addr, 1) != 0) {
+        return -1;
+    }
+
+    if (i2c_->read(I2C_ADDR, &data, 1) != 0) {
+        return -1;
+    }
+
+    if (data != 0x55) {
+        return -1;
+    }
+
+    return 0;
+}
+
+//******************************************************************************
+int BMP180::startPressure(BMP180::oversampling_t oss)
+{
+    char data[2];
+
+    data[0] = REG_ADDR_CTRL;
+    data[1] = CTRL_REG_PRESS_0 | ((oss & 0x3) << 6);
+    oss_ = oss;
+
+    if (i2c_->write(I2C_ADDR, data, 2) != 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+//******************************************************************************
+int BMP180::getPressure(int *pressure)
+{
+    char addr, byte[3];
+    uint32_t up;
+    int32_t b6, x1, x2, x3, b3, p;
+    uint32_t b4, b7;
+
+    addr = REG_ADDR_DATA;
+    if (i2c_->write(I2C_ADDR, &addr, 1) != 0) {
+        return -1;
+    }
+
+    if (i2c_->read(I2C_ADDR, byte, 3) != 0) {
+        return -1;
+    }
+
+    up = ((byte[0] << 16) | (byte[1] << 8) | byte[2]) >> (8 - oss_);
+
+    b6 = b5 - 4000;
+    x1 = (b6 * b6) >> 12;
+    x1 *= calib.b2;
+    x1 >>= 11;
+    x2 = calib.ac2 * b6;
+    x2 >>= 11;
+    x3 = x1 + x2;
+    b3 = (((((int32_t)calib.ac1) * 4 + x3) << oss_) + 2);
+    b3 >>= 2;
+
+    x1 = (calib.ac3 * b6) >> 13;
+    x2 = (calib.b1 * ((b6 * b6) >> 12)) >> 16;
+    x3 = (x1 + x2 + 2) >> 2;
+    b4 = (calib.ac4 * (uint32_t)(x3 + 32768)) >> 15;
+    b7 = ((uint32_t)up - b3) * (50000 >> oss_);
+    p = ((b7 < 0x80000000) ? ((b7 << 1) / b4) : ((b7 / b4) * 2));
+    x1 = p >> 8;
+    x1 *= x1;
+    x1 = (x1 * 3038) >> 16;
+    x2 = (-7357 * p) >> 16;
+    p += (x1 + x2 + 3791) >> 4;
+
+    *pressure = p;
+
+    return 0;
+}
+
+//******************************************************************************
+int BMP180::startTemperature(void)
+{
+    char data[2] = { REG_ADDR_CTRL, CTRL_REG_TEMP };
+
+    if (i2c_->write(I2C_ADDR, data, 2) != 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+//******************************************************************************
+int BMP180::getTemperature(float *tempC)
+{
+    char addr, byte[2];
+    uint16_t ut;
+    int32_t x1, x2;
+
+    addr = REG_ADDR_DATA;
+    if (i2c_->write(I2C_ADDR, &addr, 1) != 0) {
+        return -1;
+    }
+
+    if (i2c_->read(I2C_ADDR, byte, 2) != 0) {
+        return -1;
+    }
+
+    ut = (byte[0] << 8) | byte[1];
+
+    x1 = ((ut - calib.ac6) * calib.ac5) >> 15;
+    x2 = (calib.mc << 11) / (x1 + calib.md);
+    b5 = x1 + x2;
+
+    *tempC = (float)(b5 + 8) / 160;
+
+    return 0;
+}
+
+//******************************************************************************
+int BMP180::getTemperature(int16_t *tempCx10)
+{
+    char addr, byte[2];
+    uint16_t ut;
+    int32_t x1, x2;
+
+    addr = REG_ADDR_DATA;
+    if (i2c_->write(I2C_ADDR, &addr, 1) != 0) {
+        return -1;
+    }
+
+    if (i2c_->read(I2C_ADDR, byte, 2) != 0) {
+        return -1;
+    }
+
+    ut = (byte[0] << 8) | byte[1];
+
+    x1 = ((ut - calib.ac6) * calib.ac5) >> 15;
+    x2 = (calib.mc << 11) / (x1 + calib.md);
+    b5 = x1 + x2;
+
+    *tempCx10 = (b5 + 8) >> 4;
+
+    return 0;
+}

diff -r 000000000000 -r b2219e6e444b BMP180.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMP180.h	Fri Apr 17 09:31:09 2015 -0500
@@ -0,0 +1,230 @@
+/*******************************************************************************
+ * Copyright (C) 2015 Maxim Integrated Products, Inc., All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
+ * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Except as contained in this notice, the name of Maxim Integrated
+ * Products, Inc. shall not be used except as stated in the Maxim Integrated
+ * Products, Inc. Branding Policy.
+ *
+ * The mere transfer of this software does not imply any licenses
+ * of trade secrets, proprietary technology, copyrights, patents,
+ * trademarks, maskwork rights, or any other form of intellectual
+ * property whatsoever. Maxim Integrated Products, Inc. retains all
+ * ownership rights.
+ *******************************************************************************
+ */
+
+#ifndef _BMP180_H_
+#define _BMP180_H_
+
+#include "mbed.h"
+
+/**
+ * Bosch BMP180 Digital Pressure Sensor
+ *
+ * @code
+ * #include <stdio.h>
+ * #include "mbed.h"
+ * #include "BMP180.h"
+ *
+ * I2C i2c(I2C_SDA, I2C_SCL);
+ * BMP180 bmp180(&i2c);
+ *
+ * int main(void) {
+ *
+ *     while(1) {
+ *         if (bmp180.init() != 0) {
+ *             printf("Error communicating with BMP180\n");
+ *         } else {
+ *             printf("Initialized BMP180\n");
+ *             break;
+ *         }
+ *         wait(1);
+ *     }
+ *
+ *     while(1) {
+ *         bmp180.startTemperature();
+ *         wait_ms(5);     // Wait for conversion to complete
+ *         float temp;
+ *         if(bmp180.getTemperature(&temp) != 0) {
+ *             printf("Error getting temperature\n");
+ *             continue;
+ *         }
+ *
+ *         bmp180.startPressure(BMP180::ULTRA_LOW_POWER);
+ *         wait_ms(10);    // Wait for conversion to complete
+ *         int pressure;
+ *         if(bmp180.getPressure(&pressure) != 0) {
+ *             printf("Error getting pressure\n");
+ *             continue;
+ *         }
+ *
+ *         printf("Pressure = %d Pa Temperature = %f C\n", pressure, temp);
+ *         wait(1);
+ *     }
+ * }
+ * @endcode
+ */
+class BMP180
+{
+
+public:
+
+    /**
+     * @brief   Oversampling ratio.
+     * @details Dictates how many pressure samples to take. Conversion time varies
+     *          depending on the number of samples taken. Refer to data sheet
+     *          for timing specifications.
+     */
+    typedef enum {
+        ULTRA_LOW_POWER       = 0, ///< 1 pressure sample
+        STANDARD              = 1, ///< 2 pressure samples
+        HIGH_RESOLUTION       = 2, ///< 4 pressure samples
+        ULTRA_HIGH_RESOLUTION = 3, ///< 8 pressure samples
+    } oversampling_t;
+
+    /**
+     * BMP180 constructor.
+     *
+     * @param sda mbed pin to use for SDA line of I2C interface.
+     * @param scl mbed pin to use for SCL line of I2C interface.
+     */
+    BMP180(PinName sda, PinName scl);
+
+    /**
+     * BMP180 constructor.
+     *
+     * @param i2c I2C object to use.
+     */
+    BMP180(I2C *i2c);
+
+    /**
+     * BMP180 destructor.
+     */
+    ~BMP180();
+
+    /**
+     * @brief   Initialize BMP180.
+     * @details Gets the device ID and saves the calibration values.
+     * @returns 0 if no errors, -1 if error.
+     */
+    int init(void);
+
+    /**
+     * @brief   Reset BMP180.
+     * @details Performs a soft reset of the device. Same sequence as power on reset.
+     * @returns 0 if no errors, -1 if error.
+     */
+    int reset(void);
+
+    /**
+     * @brief   Check ID.
+     * @details Checks the device ID, should be 0x55 on reset.
+     * @returns 0 if no errors, -1 if error.
+     */
+    int checkId(void);
+
+    /**
+     * @brief   Start pressure conversion.
+     * @details Initiates the pressure conversion sequence. Refer to data sheet
+     *          for timing specifications.
+     *
+     * @param   oss Number of samples to take.
+     * @returns 0 if no errors, -1 if error.
+     */
+    int startPressure(BMP180::oversampling_t oss);
+
+    /**
+     * @brief   Get pressure reading.
+     * @details Calculates the pressure using the data calibration data and formula.
+     *          Pressure is reported in Pascals.
+     * @note    This function should be called after calling startPressure().
+     *          Refer to the data sheet for the timing requirements. Calling this
+     *          function too soon can result in oversampling.
+     *
+     * @param   pressure Pointer to store pressure reading.
+     * @returns 0 if no errors, -1 if error.
+     */
+    int getPressure(int *pressure);
+
+    /**
+     * @brief   Start temperature conversion.
+     * @details Initiates the temperature conversion sequence. Refer to data
+     *          sheet for timing specifications.
+     * @returns 0 if no errors, -1 if error.
+     */
+    int startTemperature(void);
+
+    /**
+     * @brief   Get temperature reading.
+     * @details Calculates the temperature using the data calibration data and formula.
+     *          Temperature is reported in degrees Celcius.
+     *
+     * @note    This function should be called after calling startTemperature().
+     *          Refer to the data sheet for the timing requirements. Calling this
+     *          function too soon can result in oversampling.
+     *
+     * @param   tempC Pointer to store temperature reading.
+     * @returns 0 if no errors, -1 if error.
+     */
+    int getTemperature(float *tempC);
+
+    /**
+     * @brief   Get temperature reading.
+     * @details Calculates the temperature using the data calibration data and formula.
+     *          Temperature is reported in 1/10ths degrees Celcius.
+     *
+     * @note    This function should be called after calling startTemperature().
+     *          Refer to the data sheet for the timing requirements. Calling this
+     *          function too soon can result in oversampling.
+     *
+     * @param   tempCx10 Pointer to store temperature reading.
+     * @returns 0 if no errors, -1 if error.
+     */
+    int getTemperature(int16_t *tempCx10);
+
+private:
+
+    typedef union {
+        uint16_t value[11];
+        struct {
+            int16_t ac1;
+            int16_t ac2;
+            int16_t ac3;
+            uint16_t ac4;
+            uint16_t ac5;
+            uint16_t ac6;
+            int16_t b1;
+            int16_t b2;
+            int16_t mb;
+            int16_t mc;
+            int16_t md;
+        };
+    } calibration_t;
+
+    I2C *i2c_;
+    bool i2c_owner;
+
+    BMP180::calibration_t calib;
+    int32_t b5;
+    BMP180::oversampling_t oss_;
+};
+
+#endif /* _BMP180_H_ */