394 lines
12 KiB
C
394 lines
12 KiB
C
/****************************************************************************
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* drivers/sensors/mpl115a.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/* Character driver for the Freescale MPL115A1 Barometer Sensor */
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdlib.h>
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#include <fixedmath.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/signal.h>
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#include <nuttx/random.h>
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#include <nuttx/fs/fs.h>
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#include <nuttx/spi/spi.h>
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#include <nuttx/sensors/mpl115a.h>
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#if defined(CONFIG_SPI) && defined(CONFIG_SENSORS_MPL115A)
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private
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****************************************************************************/
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struct mpl115a_dev_s
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{
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FAR struct spi_dev_s *spi; /* SPI interface */
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int16_t mpl115a_cal_a0;
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int16_t mpl115a_cal_b1;
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int16_t mpl115a_cal_b2;
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int16_t mpl115a_cal_c12;
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uint16_t mpl115a_temperature;
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uint16_t mpl115a_pressure;
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};
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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static inline void mpl115a_configspi(FAR struct spi_dev_s *spi);
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static uint8_t mpl115a_getreg8(FAR struct mpl115a_dev_s *priv,
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uint8_t regaddr);
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static void mpl115a_updatecaldata(FAR struct mpl115a_dev_s *priv);
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static void mpl115a_read_press_temp(FAR struct mpl115a_dev_s *priv);
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static int mpl115a_getpressure(FAR struct mpl115a_dev_s *priv);
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/* Character driver methods */
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static ssize_t mpl115a_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t mpl115a_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_mpl115afops =
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{
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NULL, /* open */
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NULL, /* close */
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mpl115a_read, /* read */
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mpl115a_write, /* write */
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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static inline void mpl115a_configspi(FAR struct spi_dev_s *spi)
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{
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/* Configure SPI for the MPL115A */
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SPI_SETMODE(spi, SPIDEV_MODE0);
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SPI_SETBITS(spi, 8);
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SPI_HWFEATURES(spi, 0);
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SPI_SETFREQUENCY(spi, MPL115A_SPI_MAXFREQUENCY);
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}
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/****************************************************************************
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* Name: mpl115a_getreg8
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*
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* Description:
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* Read from an 8-bit MPL115A register
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*
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****************************************************************************/
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static uint8_t mpl115a_getreg8(FAR struct mpl115a_dev_s *priv,
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uint8_t regaddr)
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{
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uint8_t regval;
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/* If SPI bus is shared then lock and configure it */
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SPI_LOCK(priv->spi, true);
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mpl115a_configspi(priv->spi);
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/* Select the MPL115A */
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SPI_SELECT(priv->spi, SPIDEV_BAROMETER(0), true);
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/* Send register to read and get the next byte */
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SPI_SEND(priv->spi, regaddr);
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SPI_RECVBLOCK(priv->spi, ®val, 1);
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/* Deselect the MPL115A */
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SPI_SELECT(priv->spi, SPIDEV_BAROMETER(0), false);
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/* Unlock bus */
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SPI_LOCK(priv->spi, false);
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#ifdef CONFIG_MPL115A_REGDEBUG
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_err("%02x->%02x\n", regaddr, regval);
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#endif
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return regval;
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}
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/****************************************************************************
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* Name: mpl115a_updatecaldata
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*
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* Description:
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* Update Calibration Coefficient Data
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*
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****************************************************************************/
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static void mpl115a_updatecaldata(FAR struct mpl115a_dev_s *priv)
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{
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/* Get a0 coefficient */
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priv->mpl115a_cal_a0 =
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_A0_MSB << 1)) << 8;
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priv->mpl115a_cal_a0 |=
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_A0_LSB << 1));
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sninfo("a0 = %d\n", priv->mpl115a_cal_a0);
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/* Get b1 coefficient */
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priv->mpl115a_cal_b1 =
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_B1_MSB << 1)) << 8;
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priv->mpl115a_cal_b1 |=
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_B1_LSB << 1));
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sninfo("b1 = %d\n", priv->mpl115a_cal_b1);
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/* Get b2 coefficient */
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priv->mpl115a_cal_b2 =
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_B2_MSB << 1)) << 8;
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priv->mpl115a_cal_b2 |=
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_B2_LSB << 1));
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sninfo("b2 = %d\n", priv->mpl115a_cal_b2);
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/* Get c12 coefficient */
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priv->mpl115a_cal_c12 =
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_C12_MSB << 1)) << 8;
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priv->mpl115a_cal_c12 |=
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_C12_LSB << 1));
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sninfo("c12 = %d\n", priv->mpl115a_cal_c12);
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}
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/****************************************************************************
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* Name: mpl115a_read_press_temp
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*
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* Description:
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* Read raw pressure and temperature from MPL115A and store it in the
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* mpl115a_dev_s structure.
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*
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****************************************************************************/
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static void mpl115a_read_press_temp(FAR struct mpl115a_dev_s *priv)
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{
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/* Start a new conversion */
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mpl115a_getreg8(priv, (MPL115A_CONVERT << 1));
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/* Delay 5ms */
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nxsig_usleep(5000);
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priv->mpl115a_pressure =
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_PADC_MSB << 1)) << 8;
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priv->mpl115a_pressure |=
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_PADC_LSB << 1));
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priv->mpl115a_pressure >>= 6; /* Padc is 10bit unsigned */
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sninfo("Pressure = %d\n", priv->mpl115a_pressure);
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priv->mpl115a_temperature =
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_TADC_MSB << 1)) << 8;
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priv->mpl115a_temperature |=
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mpl115a_getreg8(priv, MPL115A_BASE_CMD | (MPL115A_TADC_LSB << 1));
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priv->mpl115a_temperature >>= 6; /* Tadc is 10bit unsigned */
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sninfo("Temperature = %d\n", priv->mpl115a_temperature);
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/* Feed sensor data to entropy pool */
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add_sensor_randomness((priv->mpl115a_pressure << 16) ^
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priv->mpl115a_temperature);
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}
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/****************************************************************************
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* Name: mpl115a_getpressure
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*
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* Description:
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* Calculate the Barometric Pressure using the temperature compensated
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* See Freescale AN3785 and MPL115A1 data sheet for details
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*
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****************************************************************************/
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static int mpl115a_getpressure(FAR struct mpl115a_dev_s *priv)
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{
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int32_t c12x2;
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int32_t a1;
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int32_t a1x1;
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int32_t y1;
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int32_t a2x2;
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int32_t pcomp;
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uint16_t padc;
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uint16_t tadc;
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uint16_t pressure;
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/* Check if coefficient data were read correctly */
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if ((priv->mpl115a_cal_a0 == 0) || (priv->mpl115a_cal_b1 == 0) ||
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(priv->mpl115a_cal_b2 == 0) || (priv->mpl115a_cal_c12 == 0))
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{
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mpl115a_updatecaldata(priv);
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}
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/* Read temperature and pressure */
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mpl115a_read_press_temp(priv);
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padc = priv->mpl115a_pressure;
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tadc = priv->mpl115a_temperature;
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/* These code are from Freescale AN3785 */
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c12x2 = ((int32_t)priv->mpl115a_cal_c12 * tadc) >> 11;
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a1 = (int32_t) (priv->mpl115a_cal_b1 + c12x2);
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a1x1 = a1 * padc;
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y1 = (((int32_t)priv->mpl115a_cal_a0) << 10) + a1x1;
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a2x2 = (((int32_t)priv->mpl115a_cal_b2) * tadc) >> 1;
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pcomp = (y1 + a2x2) >> 9;
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/* Calculate the pressure in 1/16 kPa from compensated */
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pressure = (((((int32_t)pcomp) * 1041) >> 14) + 800);
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/* Note that the final pressure value is reported with 4 bit fractional
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* This may be eliminated by right shifting the result 4 bits.
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*/
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sninfo("Final Pressure = %d\n", pressure >> 4);
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return pressure;
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}
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/****************************************************************************
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* Name: mpl115a_read
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****************************************************************************/
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static ssize_t mpl115a_read(FAR struct file *filep,
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FAR char *buffer, size_t buflen)
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{
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FAR struct inode *inode = filep->f_inode;
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FAR struct mpl115a_dev_s *priv = inode->i_private;
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FAR uint16_t *press = (FAR uint16_t *) buffer;
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if (!buffer)
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{
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snerr("ERROR: Buffer is null\n");
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return -1;
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}
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if (buflen != 2)
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{
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snerr("ERROR:");
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snerr(" You can't read something other than 16 bits (2 bytes)\n");
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return -1;
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}
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/* Get the pressure compensated */
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*press = mpl115a_getpressure(priv);
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/* Return size of uint16_t (2 bytes) */
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return 2;
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}
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/****************************************************************************
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* Name: mpl115a_write
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****************************************************************************/
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static ssize_t mpl115a_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen)
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{
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return -ENOSYS;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mpl115a_register
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*
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* Description:
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* Register the MPL115A character device as 'devpath'
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*
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* Input Parameters:
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* devpath - The full path to the driver to register. E.g., "/dev/temp0"
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* i2c - An instance of the I2C interface to use to communicate with
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* MPL115A
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* addr - The I2C address of the LM-75. The base I2C address of the
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* MPL115A is 0x48. Bits 0-3 can be controlled to get 8 unique
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* addresses from 0x48 through 0x4f.
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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****************************************************************************/
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int mpl115a_register(FAR const char *devpath, FAR struct spi_dev_s *spi)
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{
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FAR struct mpl115a_dev_s *priv;
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int ret;
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/* Initialize the MPL115A device structure */
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priv = (FAR struct mpl115a_dev_s *)
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kmm_malloc(sizeof(struct mpl115a_dev_s));
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if (!priv)
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{
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snerr("ERROR: Failed to allocate instance\n");
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return -ENOMEM;
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}
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priv->spi = spi;
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priv->mpl115a_cal_a0 = 0;
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priv->mpl115a_cal_b1 = 0;
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priv->mpl115a_cal_b2 = 0;
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priv->mpl115a_cal_c12 = 0;
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/* Read the coefficient value */
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mpl115a_updatecaldata(priv);
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/* Register the character driver */
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ret = register_driver(devpath, &g_mpl115afops, 0666, priv);
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if (ret < 0)
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{
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snerr("ERROR: Failed to register driver: %d\n", ret);
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kmm_free(priv);
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}
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return ret;
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}
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#endif /* CONFIG_SPI && CONFIG_SENSORS_MPL115A */
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