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https://github.com/RIOT-OS/RIOT.git
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141 lines
3.7 KiB
C
141 lines
3.7 KiB
C
/*
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* Copyright (C) 2019 Inria
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup drivers_ds75lx
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* @{
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*
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* @file
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* @brief Device driver implementation for the DS75LX temperature sensor.
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*
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* @author Alexandre Abadie <alexandre.abadie@inria.fr>
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*
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* @}
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*/
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#include <stdio.h>
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#include "xtimer.h"
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#include "ds75lx.h"
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#include "ds75lx_internals.h"
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#include "ds75lx_params.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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#define DEV_I2C (dev->params.i2c)
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#define DEV_ADDR (dev->params.addr)
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static int _update_configuration_bits(const ds75lx_t *dev, uint8_t bit,
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uint8_t mask, bool set)
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{
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/* Acquire exclusive access */
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i2c_acquire(DEV_I2C);
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uint8_t config;
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if (i2c_read_reg(DEV_I2C, DEV_ADDR, DS75LX_REG_CONFIGURATION, &config, 0) < 0) {
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DEBUG("[ds75lx] error reading configuration register\n");
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/* Release I2C device */
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i2c_release(DEV_I2C);
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return -DS75LX_ERR_I2C;
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}
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DEBUG("[ds75lx] initial configuration register value: 0x%02X\n", config);
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/* clear bits */
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config &= ~mask;
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/* set bits if required */
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if (set) {
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config |= bit;
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}
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DEBUG("[ds75lx] configuration register value: 0x%02X\n", config);
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if (i2c_write_reg(DEV_I2C, DEV_ADDR, DS75LX_REG_CONFIGURATION, config, 0) < 0) {
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DEBUG("[ds75lx] error writing configuration register\n");
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/* Release I2C device */
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i2c_release(DEV_I2C);
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return -DS75LX_ERR_I2C;
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}
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/* Release I2C device */
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i2c_release(DEV_I2C);
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return DS75LX_OK;
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}
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int ds75lx_init(ds75lx_t *dev, const ds75lx_params_t *params)
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{
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dev->params = *params;
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/* Set resolution bits + force shutdown of sensor */
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return _update_configuration_bits(dev,
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(dev->params.resolution << DS75LX_CONF_R0_POS) | (1 << DS75LX_CONF_SD_POS),
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(DS75LX_CONF_R0_MASK | (1 << DS75LX_CONF_SD_POS)), true);
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}
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int ds75lx_read_temperature(const ds75lx_t *dev, int16_t *temperature)
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{
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/* Acquire exclusive access */
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i2c_acquire(DEV_I2C);
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uint8_t tmp[2];
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uint16_t temp;
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if (i2c_read_regs(DEV_I2C, DEV_ADDR, DS75LX_REG_TEMPERATURE, tmp, 2, 0) < 0) {
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DEBUG("[ds75lx] error reading temperature register\n");
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/* Release I2C device */
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i2c_release(DEV_I2C);
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return -DS75LX_ERR_I2C;
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}
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/* Release I2C device */
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i2c_release(DEV_I2C);
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temp = (tmp[0] << 8) | tmp[1];
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DEBUG("[ds75lx] temperature register content 0x%04X\n", temp);
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/* isolate integer part of the temperature */
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int8_t temp_int = (temp & 0xff00) >> 8;
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/* compute fractional part of the temperature, the LSB bits 3 to 0 are
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always zero and not used in the conversion */
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uint8_t temp_frac = (temp & 0x00f0) >> 4;
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/* fractional part is a multiple of 0.0625. Temperature is returned in c°C */
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*temperature = (temp_int * 100 + ((uint16_t)temp_frac * 100 >> 4));
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return DS75LX_OK;
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}
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int ds75lx_wakeup(const ds75lx_t *dev)
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{
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/* disable shutdown bit in configuration register */
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int ret = _update_configuration_bits(dev, (1 << DS75LX_CONF_SD_POS),
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(1 << DS75LX_CONF_SD_POS), false);
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if (ret == DS75LX_OK) {
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/* Wait max conversion time (depends on resolution) */
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xtimer_msleep((DS75LX_MAX_CONVERSION_TIME << dev->params.resolution));
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}
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return ret;
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}
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int ds75lx_shutdown(const ds75lx_t *dev)
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{
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/* enable shutdown bit in configuration register */
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return _update_configuration_bits(dev, (1 << DS75LX_CONF_SD_POS),
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(1 << DS75LX_CONF_SD_POS), true);
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}
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