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bac5cda1e3
In general, data transferred through I2C are bytes and thus should have type uint8_t, not char. Also convert uint8_t ptrs to void ptrs
139 lines
3.7 KiB
C
139 lines
3.7 KiB
C
/*
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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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* details.
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*/
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/**
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* @ingroup driver_srf02
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* @{
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*
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* @file
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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 "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 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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/**
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* @brief Some additional SRF02 commands
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* @{
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*/
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#define CMD_ADDR_SEQ1 (0xa0)
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#define CMD_ADDR_SEQ2 (0xaa)
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#define CMD_ADDR_SEQ3 (0xa5)
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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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dev->i2c = i2c;
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dev->addr = (addr >> 1); /* internally we right align the 7-bit addr */
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uint8_t 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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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, dev->addr, REG_CMD, &rev);
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if (rev == 0 || rev == 255) {
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i2c_release(dev->i2c);
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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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DEBUG("[srf02] initialization successful\n");
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return 0;
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}
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void srf02_trigger(srf02_t *dev, srf02_mode_t mode)
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{
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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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i2c_write_reg(dev->i2c, dev->addr, REG_CMD, mode);
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i2c_release(dev->i2c);
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}
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uint16_t srf02_read(srf02_t *dev)
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{
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uint8_t res[2];
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/* read the results */
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i2c_acquire(dev->i2c);
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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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/* 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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uint16_t srf02_get_distance(srf02_t *dev, srf02_mode_t mode)
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{
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/* trigger a new reading */
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srf02_trigger(dev, mode);
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/* give the sensor the required time for sampling */
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xtimer_usleep(SRF02_RANGE_DELAY);
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/* get the results */
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return srf02_read(dev);
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}
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void srf02_set_addr(srf02_t *dev, uint8_t new_addr)
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{
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/* get access to the bus */
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i2c_acquire(dev->i2c);
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DEBUG("[srf02] reprogramming device address to 0x%02x\n", (int)new_addr);
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/* write the new address, for this we need to follow a certain sequence */
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i2c_write_reg(dev->i2c, dev->addr, REG_CMD, CMD_ADDR_SEQ1);
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i2c_write_reg(dev->i2c, dev->addr, REG_CMD, CMD_ADDR_SEQ2);
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i2c_write_reg(dev->i2c, dev->addr, REG_CMD, CMD_ADDR_SEQ3);
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i2c_write_reg(dev->i2c, dev->addr, REG_CMD, new_addr);
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dev->addr = (new_addr >> 1);
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/* release the bus */
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i2c_release(dev->i2c);
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}
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