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https://github.com/RIOT-OS/RIOT.git
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drivers/srf02: various optimizations
- switched to use xtimer - simplified interface slightly - optimized reading of results - some style cleanups - updated the documentation
This commit is contained in:
Hauke Petersen
parent
8afecdd8a6
commit
d99aaff2fb
@ -279,3 +279,7 @@ ifneq (,$(filter encx24j600,$(USEMODULE)))
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USEMODULE += timex
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USEMODULE += vtimer
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endif
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ifneq (,$(filter srf02,$(USEMODULE)))
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USEMODULE += xtimer
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endif
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@ -1,5 +1,6 @@
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/*
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* Copyright (C) 2013 Zakaria Kasmi <zkasmi@inf.fu-berlin.de>
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* 2015 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser General
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* Public License v2.1. See the file LICENSE in the top level directory for more
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@ -7,27 +8,22 @@
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*/
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/**
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* @defgroup driver_srf02 SRF02 ultrasonic range sensor
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* @defgroup driver_srf02 SRF02
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* @ingroup drivers
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* @brief Driver for the SRF02 ultrasonic range sensor
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*
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* The connection between the MCU and the SRF02 is based on the i2c-interface.
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*
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* @{
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*
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* @file
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* @brief Driver definitions for the SRF02 ultrasonic ranger.
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*
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* The connection between the SRF02 and the MCU is based on the i2c interface.
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*
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* @author Zakaria Kasmi <zkasmi@inf.fu-berlin.de>
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* @author Peter Kietzmann <peter.kietzmann@haw-hamburg.de>
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*/
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#ifndef SRF02_H_
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#define SRF02_H_
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#include <stdint.h>
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#include "periph/i2c.h"
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@ -35,20 +31,13 @@
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extern "C" {
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#endif
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/** @brief The sensors default I2C address */
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/**
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* @brief Default I2C address of SRF02 sensors
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*/
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#define SRF02_DEFAULT_ADDR 112
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/** @brief The command register which defines measurement mode */
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#define SRF02_COMMAND_REG 0x0
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/** @brief The upper measurement byte */
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#define SRF02_RANGE_HIGH_BYTE 0x2
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/** @brief The lower measurement byte */
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#define SRF02_RANGE_LOW_BYTE 0x3
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/**
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* @brief Device descriptor for SRF02 sensors
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* @brief Device descriptor for SRF02 sensors
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*/
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typedef struct {
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i2c_t i2c; /**< I2C device the sensor is connected to */
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@ -56,45 +45,42 @@ typedef struct {
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} srf02_t;
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/**
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* @brief Possible measurement modes for the SRF02 sensor
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* @brief Possible measurement modes of the SRF02 sensor
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*/
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typedef enum {
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SRF02_MODE_REAL_INCH = 0x50, /**< result in inches */
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SRF02_MODE_REAL_CM = 0x51, /**< result in centimeters */
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SRF02_REAL_RANGING_MODE_MICRO_SEC = 0x52, /**< result in microseconds */
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SRF02_FAKE_RANGING_MODE_INCH = 0x56, /**< synchronous measurement in inches */
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SRF02_FAKE_RANGING_MODE_CM = 0x57, /**< synchronous measurement in centimeters */
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SRF02_FAKE_RANGING_MODE_MICRO_SEC = 0x58 /**< synchronous measurement in microseconds */
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}srf02_mode_t;
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SRF02_MODE_REAL_INCH = 0x50, /**< result in inches */
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SRF02_MODE_REAL_CM = 0x51, /**< result in centimeters */
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SRF02_MODE_REAL_MS = 0x52, /**< result in microseconds */
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SRF02_MODE_FAKE_INCH = 0x56, /**< result in inches (no pulse send) */
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SRF02_MODE_FAKE_CM = 0x57, /**< result in cm (no pulse send) */
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SRF02_MODE_FAKE_MS = 0x58 /**< result in ms (no pulse send) */
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} srf02_mode_t;
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/**
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* @brief Initialize the SRF02 ultrasonic sensor
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* @brief Initialize the SRF02 ultrasonic sensor
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*
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* @param[in] dev device descriptor of an SRF02 sensor
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* @param[in] i2c I2C device the sensor is connected to
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* @param[in] addr I2C address of the sensor
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* @param[in] speed I2C speed mode
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*
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* @return 0 on successful initialization
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* @return -1 on undefined device given
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* @return -2 on unsupported speed value
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* @return -1 on error
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*/
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int srf02_init(srf02_t *dev, i2c_t i2c, uint8_t addr, i2c_speed_t speed);
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int srf02_init(srf02_t *dev, i2c_t i2c, uint8_t addr);
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/**
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* @brief Get the distance measured from the SRF02 ultrasonic sensor
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* The result of a ranging can be returned in inches,
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* centimeters or microseconds
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* @brief Get the distance measured from the SRF02 ultrasonic sensor
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*
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* The result of the ranging operation is returned in inches, centimeters or
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* microseconds - depending on the given @p mode parameter.
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*
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* @param[in] dev device descriptor of an SRF02 sensor
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* @param[in] mode there are three real ranging modes, which return
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* the result in inches, centimeters or microseconds.
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* Another set of three fake ranging modes do the same
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* but without transmitting the burst
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*
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* @return -1 on undefined device given
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* @return the ranging result in inches, centimeters or microseconds. In the
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* case of the fake ranging mode a zero value is returned. UINT16_MAX
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* is returned if write/read action from the i2c-interface is failed.
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* @return the ranging result in inches, centimeters or microseconds
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*
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*/
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uint16_t srf02_get_distance(srf02_t *dev, srf02_mode_t mode);
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@ -103,5 +89,5 @@ uint16_t srf02_get_distance(srf02_t *dev, srf02_mode_t mode);
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}
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#endif
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/** @} */
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#endif /* SRF02_H_ */
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/** @} */
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@ -1,5 +1,6 @@
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/*
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* Copyright (C) 2013 Zakaria Kasmi <zkasmi@inf.fu-berlin.de>
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* 2015 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser General
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* Public License v2.1. See the file LICENSE in the top level directory for more
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@ -11,91 +12,93 @@
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* @{
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*
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* @file
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* @brief Driver for the SRF02 ultrasonic ranger.
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* The connection between the MCU and the SRF02 is based on the
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* i2c-interface.
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* @brief Driver for the SRF02 ultrasonic range sensor
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*
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* @author Zakaria Kasmi <zkasmi@inf.fu-berlin.de>
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* @author Peter Kietzmann <peter.kietzmann@haw-hamburg.de>
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*
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* @}
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*/
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#include <stdint.h>
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#include <stdio.h>
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#include "hwtimer.h"
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#include "xtimer.h"
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#include "srf02.h"
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#include "periph/i2c.h"
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#define ENABLE_DEBUG (0)
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#include "debug.h"
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/**
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* @brief The datasheet tells us, that ranging takes 70ms
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*/
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#define RANGE_DELAY (70000U)
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int srf02_init(srf02_t *dev, i2c_t i2c, uint8_t addr, i2c_speed_t speed)
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/**
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* @brief Per default use normal speed on the I2C bus
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*/
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#define BUS_SPEED (I2C_SPEED_NORMAL)
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/**
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* @brief SRF02 register addresses
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* @{
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*/
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#define REG_CMD (0x00)
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#define REG_HIGH (0x02)
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#define REG_LOW (0x03)
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#define REG_AUTO_HIGH (0x04)
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#define REG_AUTO_LOW (0x05)
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/** @} */
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int srf02_init(srf02_t *dev, i2c_t i2c, uint8_t addr)
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{
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int status;
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dev->i2c = i2c;
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dev->addr = addr;
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char rev;
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/* Acquire exclusive access to the bus. */
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i2c_acquire(dev->i2c);
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/* initialize i2c interface */
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status = i2c_init_master(dev->i2c, speed);
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if (i2c_init_master(dev->i2c, BUS_SPEED) < 0) {
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DEBUG("[srf02] error initializing I2C bus\n");
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return -1;
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}
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/* try to read the software revision (read the CMD reg) from the device */
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i2c_read_reg(i2c, addr, REG_CMD, &rev);
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if (rev == 0 || rev == 255) {
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DEBUG("[srf02] error reading the devices software revision\n");
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return -1;
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} else {
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DEBUG("[srf02] software revision: 0x%02x\n", rev);
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}
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/* Release the bus for other threads. */
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i2c_release(dev->i2c);
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return status;
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DEBUG("[srf02] initialization successful\n");
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return 0;
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}
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uint16_t srf02_get_distance(srf02_t *dev, srf02_mode_t mode)
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{
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int status;
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char range_high_byte = 0;
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char range_low_byte = 0;
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uint16_t distance = 0;
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char res[2];
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/* Acquire exclusive access to the bus. */
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/* trigger a new measurement by writing the mode to the CMD register */
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DEBUG("[srf02] trigger new reading\n");
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i2c_acquire(dev->i2c);
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/* initialize measure mode*/
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status = i2c_write_reg(dev->i2c, dev->addr, SRF02_COMMAND_REG, mode);
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/* Release the bus for other threads. */
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i2c_write_reg(dev->i2c, dev->addr, REG_CMD, mode);
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i2c_release(dev->i2c);
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if (status < 0) {
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DEBUG("Write the ranging command to the i2c-interface is failed");
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uint16_t distance = UINT16_MAX;
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return distance;
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}
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/* give the sensor the required time for sampling */
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xtimer_usleep(RANGE_DELAY);
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hwtimer_wait(70000);
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/* Acquire exclusive access to the bus. */
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/* read the results */
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i2c_acquire(dev->i2c);
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status = i2c_read_reg(dev->i2c, dev->addr,
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SRF02_RANGE_HIGH_BYTE, &range_high_byte);
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/* Release the bus for other threads. */
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i2c_read_regs(dev->i2c, dev->addr, REG_HIGH, res, 2);
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i2c_release(dev->i2c);
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DEBUG("[srf02] result - high: 0x%02x low: 0x%02x\n", res[0], res[1]);
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if (status < 0) {
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DEBUG("Read the high echo byte from the i2c-interface is failed");
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distance = UINT16_MAX;
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return distance;
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}
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/* Acquire exclusive access to the bus. */
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i2c_acquire(dev->i2c);
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status = i2c_read_reg(dev->i2c, dev->addr,
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SRF02_RANGE_LOW_BYTE, &range_low_byte);
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/* Release the bus for other threads. */
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i2c_release(dev->i2c);
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if (status < 0) {
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DEBUG("Read the low echo byte from the i2c-interface is failed");
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distance = UINT16_MAX;
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return distance;
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}
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distance = (range_high_byte << 8) | (range_low_byte);
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return distance;
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/* compile result - TODO: fix for different host byte order other than LE */
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return ((((uint16_t)res[0]) << 8) | (res[1] & 0xff));
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}
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