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/*
* Copyright (C) 2016 Bas Stottelaar <basstottelaar@gmail.com>
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup driver_si70xx
* @{
*
* @file
* @brief Implementation of Si7006/13/20/21 sensor driver.
*
* @author Bas Stottelaar <basstottelaar@gmail.com>
*
* @}
*/
#include "xtimer.h"
#include "si70xx.h"
/**
* @brief Utility method to perform and reconstruct a measurement.
*/
static uint32_t si70xx_measure(si70xx_t *dev, uint8_t command)
{
uint8_t result[2];
i2c_acquire(dev->i2c_dev);
i2c_write_byte(dev->i2c_dev, dev->address, command);
i2c_read_bytes(dev->i2c_dev, dev->address, result, 2);
i2c_release(dev->i2c_dev);
/* reconstruct raw result */
return ((uint32_t)result[0] << 8) + (result[1] & 0xfc);
}
int si70xx_test(si70xx_t *dev)
{
uint8_t revision = si70xx_get_revision(dev);
if (revision != SI70XX_REVISION_1 && revision != SI70XX_REVISION_2) {
return -1;
}
uint8_t id = si70xx_get_id(dev);
if (id != SI70XX_ID_SI7006 && id != SI70XX_ID_SI7013 &&
id != SI70XX_ID_SI7020 && id != SI70XX_ID_SI7021) {
return -2;
}
return 0;
}
int si70xx_init(si70xx_t *dev, i2c_t i2c_dev, uint8_t address)
{
dev->i2c_dev = i2c_dev;
dev->address = address;
/* setup the i2c bus */
i2c_acquire(dev->i2c_dev);
int result = i2c_init_master(dev->i2c_dev, I2C_SPEED_NORMAL);
i2c_release(dev->i2c_dev);
if (result != 0) {
return result;
}
result = si70xx_test(dev);
if (result < 0) {
return result;
}
/* initialize the peripheral */
i2c_acquire(dev->i2c_dev);
i2c_write_byte(dev->i2c_dev, dev->address, SI70XX_RESET);
i2c_release(dev->i2c_dev);
/* sensor is ready after at most 25 ms */
xtimer_usleep(25 * US_PER_MS);
return 0;
}
uint16_t si70xx_get_relative_humidity(si70xx_t *dev)
{
uint32_t raw;
int32_t humidity;
/* perform measurement */
raw = si70xx_measure(dev, SI70XX_MEASURE_RH_HOLD);
humidity = ((12500 * raw) / 65536) - 600;
/* according to datasheet, values may exceed bounds, but can be clipped */
if (humidity < 0) {
return 0;
}
else if (humidity > 10000) {
return 10000;
}
else {
return (uint16_t) humidity;
}
}
int16_t si70xx_get_temperature(si70xx_t *dev)
{
uint32_t raw;
/* perform measurement */
raw = si70xx_measure(dev, SI70XX_MEASURE_TEMP_HOLD);
return ((17572 * raw) / 65536) - 4685;
}
void si70xx_get_both(si70xx_t *dev, uint16_t *humidity, int16_t *temperature)
{
uint32_t raw;
/* read the humidity the normal way */
*humidity = si70xx_get_relative_humidity(dev);
/* read the temperature using the data from the previous measurement */
raw = si70xx_measure(dev, SI70XX_MEASURE_TEMP_PREV);
*temperature = ((17572 * raw) / 65536) - 4685;
}
uint64_t si70xx_get_serial(si70xx_t *dev)
{
uint8_t out[2];
uint8_t in_first[8] = { 0 };
uint8_t in_second[8] = { 0 };
/* read the lower bytes */
out[0] = SI70XX_READ_ID_FIRST_A;
out[1] = SI70XX_READ_ID_FIRST_B;
i2c_acquire(dev->i2c_dev);
i2c_write_bytes(dev->i2c_dev, dev->address, out, 2);
i2c_read_bytes(dev->i2c_dev, dev->address, in_first, 8);
/* read the higher bytes */
out[0] = SI70XX_READ_ID_SECOND_A;
out[1] = SI70XX_READ_ID_SECOND_B;
i2c_write_bytes(dev->i2c_dev, dev->address, out, 2);
i2c_read_bytes(dev->i2c_dev, dev->address, in_second, 8);
i2c_release(dev->i2c_dev);
/* calculate the ID */
uint32_t id_first = ((uint32_t)in_first[0] << 24) + ((uint32_t)in_first[2] << 16) +
(in_first[4] << 8) + (in_first[6] << 0);
uint32_t id_second = ((uint32_t)in_second[0] << 24) + ((uint32_t)in_second[2] << 16) +
(in_second[4] << 8) + (in_second[6] << 0);
return (((uint64_t) id_first) << 32) + id_second;
}
uint8_t si70xx_get_id(si70xx_t *dev)
{
return (si70xx_get_serial(dev) >> 24) & 0xff;
}
uint8_t si70xx_get_revision(si70xx_t *dev)
{
uint8_t out[2];
uint8_t in = 0;
/* read the revision number */
out[0] = SI70XX_READ_REVISION_A;
out[1] = SI70XX_READ_REVISION_B;
i2c_acquire(dev->i2c_dev);
i2c_write_bytes(dev->i2c_dev, dev->address, out, 2);
i2c_read_byte(dev->i2c_dev, dev->address, &in);
i2c_release(dev->i2c_dev);
return in;
}