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sensirion_i2c_hal.c
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sensirion_i2c_hal.c
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/*
* Copyright (c) 2018, Sensirion AG
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of Sensirion AG nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/* Enable usleep function */
#define _DEFAULT_SOURCE
#include "sensirion_i2c_hal.h"
#include "sensirion_common.h"
#include "sensirion_config.h"
#include <fcntl.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <unistd.h>
/**
* Linux specific configuration. Adjust the following define to the device path
* of your sensor.
*/
#define I2C_DEVICE_PATH "/dev/i2c-1"
/**
* The following define was taken from i2c-dev.h. Alternatively the header file
* can be included. The define was added in Linux v3.10 and never changed since
* then.
*/
#define I2C_SLAVE 0x0703
#define I2C_WRITE_FAILED -1
#define I2C_READ_FAILED -1
static int i2c_device = -1;
static uint8_t i2c_address = 0;
/**
* Initialize all hard- and software components that are needed for the I2C
* communication.
*/
void sensirion_i2c_hal_init(void) {
/* open i2c adapter */
i2c_device = open(I2C_DEVICE_PATH, O_RDWR);
if (i2c_device == -1)
return; /* no error handling */
}
/**
* Release all resources initialized by sensirion_i2c_hal_init().
*/
void sensirion_i2c_hal_free(void) {
if (i2c_device >= 0)
close(i2c_device);
}
/**
* Execute one read transaction on the I2C bus, reading a given number of bytes.
* If the device does not acknowledge the read command, an error shall be
* returned.
*
* @param address 7-bit I2C address to read from
* @param data pointer to the buffer where the data is to be stored
* @param count number of bytes to read from I2C and store in the buffer
* @returns 0 on success, error code otherwise
*/
int8_t sensirion_i2c_hal_read(uint8_t address, uint8_t* data, uint16_t count) {
if (i2c_address != address) {
ioctl(i2c_device, I2C_SLAVE, address);
i2c_address = address;
}
if (read(i2c_device, data, count) != count) {
return I2C_READ_FAILED;
}
return 0;
}
/**
* Execute one write transaction on the I2C bus, sending a given number of
* bytes. The bytes in the supplied buffer must be sent to the given address. If
* the slave device does not acknowledge any of the bytes, an error shall be
* returned.
*
* @param address 7-bit I2C address to write to
* @param data pointer to the buffer containing the data to write
* @param count number of bytes to read from the buffer and send over I2C
* @returns 0 on success, error code otherwise
*/
int8_t sensirion_i2c_hal_write(uint8_t address, const uint8_t* data,
uint16_t count) {
if (i2c_address != address) {
ioctl(i2c_device, I2C_SLAVE, address);
i2c_address = address;
}
if (write(i2c_device, data, count) != count) {
return I2C_WRITE_FAILED;
}
return 0;
}
/**
* Sleep for a given number of microseconds. The function should delay the
* execution for at least the given time, but may also sleep longer.
*
* @param useconds the sleep time in microseconds
*/
void sensirion_i2c_hal_sleep_usec(uint32_t useconds) {
usleep(useconds);
}