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336 lines
11 KiB
C
336 lines
11 KiB
C
/*
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* Copyright (C) 2019 HAW Hamburg
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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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* @defgroup drivers_ad7746 AD7746 Capacitance-to-digital converter driver
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* @ingroup drivers_sensors
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* @ingroup drivers_saul
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* @brief I2C Capacitance-to-digital converter with temperature and voltage
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* sensors. The devices has two main channels: capacitance channel
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* and voltage / temperature channel.
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*
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* The capacitance channel can measure from two different inputs
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* (CIN1 and CIN2), selected using @ref ad7746_set_cap_ch_input.
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*
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* The voltage / temperature channel can measure from five different
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* sources: Voltage from VIN pins, internal VCC, internal
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* temperature sensor and external temperature sensor
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* (see datasheet for proper setup). The mode of this channel can be
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* set using @ref ad7746_set_vt_ch_mode or will directly be set
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* when trying to read from a specific source which is not the
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* currently selected one. This mode change may lead to data not
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* being available right away (in which case the reading function
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* will return @ref AD7746_NODATA error code).
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*
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* @note Constantly switching between modes in the voltage / temperature
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* channel may lead to invalid data, for what it seems to be a
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* device limitation.
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*
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* This driver provides @ref drivers_saul capabilities.
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* @{
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*
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* @file
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* @brief AD7746 Capacitance-to-digital converter with temperature
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* sensor driver
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*
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* @author Leandro Lanzieri <leandro.lanzieri@haw-hamburg.de>
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*/
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#ifndef AD7746_H
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#define AD7746_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "periph/i2c.h"
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#include "periph/gpio.h"
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/**
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* @brief 0 fF capacitance code
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*/
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#define AD7746_ZERO_SCALE_CODE (0x800000LL)
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/**
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* @brief Interval voltage reference expressed in mV
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*/
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#define AD7746_INTERNAL_VREF (1170)
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/**
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* @brief Maximum value that can be configured into the DACs.
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*/
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#define AD7746_DAC_MAX (0x7F)
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/**
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* @brief Channel numbers for reading
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*/
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enum {
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AD7746_READ_CAP_CH = 0, /**< read capacitive channel */
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AD7746_READ_VT_CH = 1 /**< read voltage / temperature channel */
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};
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/**
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* @brief Named return values
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*/
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enum {
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AD7746_OK = 0, /**< everything was fine */
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AD7746_NOI2C = -1, /**< I2C communication failed */
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AD7746_NODEV = -2, /**< no AD7746 device found on the bus */
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AD7746_NODATA = -3 /**< no data available */
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};
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/**
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* @brief Voltage / Temperature channel sample rates
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*/
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typedef enum {
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AD7746_VT_SR_498 = 0, /**< 49.8 Hz */
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AD7746_VT_SR_312 = 1, /**< 31.2 Hz */
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AD7746_VT_SR_161 = 2, /**< 16.1 Hz */
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AD7746_VT_SR_082 = 3 /**< 8.2 Hz */
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} ad7746_vt_sample_rate_t;
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/**
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* @brief Voltage / Temperature channel modes
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*/
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typedef enum {
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AD7746_VT_MD_DIS = -1, /**< channel disabled */
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AD7746_VT_MD_TEMP = 0, /**< internal temperature sensor */
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AD7746_VT_MD_ETEMP = 1, /**< external temperature sensor (see datasheet) */
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AD7746_VT_MD_VDD = 2, /**< Vdd voltage monitor */
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AD7746_VT_MD_VIN = 3 /**< external voltage input (Vin) */
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} ad7746_vt_mode_t;
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/**
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* @brief Capacitance channel input
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*/
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typedef enum {
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AD7746_CAP_IN_1 = 0, /**< CIN1 input */
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AD7746_CAP_IN_2 /**< CIN2 input */
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} ad7746_cap_input_t;
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/**
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* @brief Capacitive channel sample rate
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*/
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typedef enum {
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AD7746_CAP_SR_909 = 0, /**< 90.9 Hz */
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AD7746_CAP_SR_838 = 1, /**< 83.8 Hz */
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AD7746_CAP_SR_500 = 2, /**< 50.0 Hz */
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AD7746_CAP_SR_263 = 3, /**< 26.3 Hz */
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AD7746_CAP_SR_161 = 4, /**< 16.1 Hz */
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AD7746_CAP_SR_130 = 5, /**< 13.0 Hz */
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AD7746_CAP_SR_109 = 6, /**< 10.9 Hz */
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AD7746_CAP_SR_091 = 7 /**< 9.1 Hz */
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} ad7746_cap_sample_rate_t;
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/**
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* @brief Excitation signal output configuration
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*/
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typedef enum {
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AD7746_EXC_A = 0x06, /**< enable only exc A output */
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AD7746_EXC_B = 0x09, /**< enable only exc B output */
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AD7746_EXC_AB = 0x0A /**< enable exc A and B outputs */
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} ad7746_exc_config_t;
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/**
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* @brief AD7746 params
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*/
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typedef struct ad7746_params {
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i2c_t i2c; /**< i2c device */
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uint8_t addr; /**< i2c address */
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uint8_t dac_a_cap; /**< DAC A capacitance */
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uint8_t dac_b_cap; /**< DAC B capacitance */
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ad7746_exc_config_t exc_config; /**< excitation signal config */
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ad7746_cap_sample_rate_t cap_sample_rate; /**< capacitance sample rate */
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ad7746_vt_sample_rate_t vt_sample_rate; /**< voltage/temp sample rate */
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ad7746_vt_mode_t vt_mode; /**< mode of the voltage/temp ch */
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ad7746_cap_input_t cap_input; /**< selected capacitance input*/
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} ad7746_params_t;
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/**
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* @brief AD7746 device descriptor
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*/
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typedef struct ad7746 {
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ad7746_params_t params; /**< device driver configuration */
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} ad7746_t;
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/**
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* @brief Initializes an AD7746 device
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*
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* @param[in,out] dev device descriptor
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* @param[in] params device configuration
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*
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* @return AD7746_OK on success
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* @return AD7746_NODEV if no device is found on the bus
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* @return AD7746_NOI2C if other error occurs
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*/
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int ad7746_init(ad7746_t *dev, const ad7746_params_t *params);
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/**
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* @brief Reads the capacitance from the input 1 (CIN1). Returns the value in
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* fF.
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*
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* @note If the currently selected input does not match @ref AD7746_CAP_IN_1 it
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* will be changed to it. This may cause data not to be available right
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* away. The time until new data is available will depend on the
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* @ref ad7746_params_t::cap_sample_rate "sample rate" of the channel.
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*
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* @param[in, out] dev device descriptor
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* @param[out] value read value in fF
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*
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* @return AD7746_OK on success
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* @return AD7746_NODATA if there is no data available in the channel
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* @return AD7746_I2C if other error occurs
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*/
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int ad7746_read_capacitance_1(ad7746_t *dev, int *value);
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/**
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* @brief Reads the capacitance from the input 2 (CIN2). Returns the value in
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* fF.
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*
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* @note If the currently selected input does not match @ref AD7746_CAP_IN_2 it
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* will be changed to it. This may cause data not to be available right
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* away. The time until new data is available will depend on the
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* @ref ad7746_params_t::cap_sample_rate "sample rate" of the channel.
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*
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* @param[in, out] dev device descriptor
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* @param[out] value read value in fF
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*
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* @return AD7746_OK on success
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* @return AD7746_NODATA if there is no data available in the channel
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* @return AD7746_I2C if other error occurs
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*/
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int ad7746_read_capacitance_2(ad7746_t *dev, int *value);
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/**
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* @brief Reads the voltage from the external voltage input (VIN). Returns the
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* value in mV.
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*
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* @note If the current mode of the voltage / temperature channel does not match
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* @ref AD7746_VT_MD_VIN it will be changed to this mode, causing data not
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* to be available right away. The time until new data is available will
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* depend on the @ref ad7746_params_t::vt_sample_rate "sample rate" of the
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* channel.
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*
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* @param[in, out] dev device descriptor
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* @param[out] value read value in mV
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*
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* @return AD7746_OK on success
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* @return AD7746_NODATA if there is no data available in the channel
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* @return AD7746_I2C if other error occurs
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*/
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int ad7746_read_voltage_in(ad7746_t *dev, int *value);
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/**
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* @brief Reads the voltage from the VDD pin. Returns the value in mV.
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*
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* @note If the current mode of the voltage / temperature channel does not match
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* @ref AD7746_VT_MD_VDD it will be changed to this mode, causing data not
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* to be available right away. The time until new data is available will
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* depend on the @ref ad7746_params_t::vt_sample_rate "sample rate" of the
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* channel.
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*
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* @param[in, out] dev device descriptor
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* @param[out] value read value in mV
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*
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* @return AD7746_OK on success
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* @return AD7746_NODATA if there is no data available in the channel
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* @return AD7746_I2C if other error occurs
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*/
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int ad7746_read_voltage_vdd(ad7746_t *dev, int *value);
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/**
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* @brief Reads the temperature from the internal sensor.
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*
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* @note If the current mode of the voltage / temperature channel does not match
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* @ref AD7746_VT_MD_TEMP it will be changed to this mode, causing data
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* not to be available right away. The time until new data is available
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* will depend on the @ref ad7746_params_t::vt_sample_rate "sample rate"
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* of the channel.
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*
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* @param[in, out] dev device descriptor
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* @param[out] value read value in celsius
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*
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* @return AD7746_OK on success
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* @return AD7746_NODATA if there is no data available in the channel
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* @return AD7746_I2C if other error occurs
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*/
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int ad7746_read_temperature_int(ad7746_t *dev, int *value);
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/**
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* @brief Reads the temperature from the external sensor (see datasheet).
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*
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* @note If the current mode of the voltage / temperature channel does not match
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* @ref AD7746_VT_MD_ETEMP it will be changed to this mode, causing data
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* not to be available right away. The time until new data is available
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* will depend on the @ref ad7746_params_t::vt_sample_rate "sample rate"
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* of the channel.
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*
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* @param[in, out] dev device descriptor
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* @param[out] value read value in celsius
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*
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* @return AD7746_OK on success
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* @return AD7746_NODATA if there is no data available in the channel
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* @return AD7746_I2C if other error occurs
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*/
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int ad7746_read_temperature_ext(ad7746_t *dev, int *value);
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/**
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* @brief Sets the current input for the capacitive measurement.If not
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configured manually, the driver sets the correct mode within
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the dedicated read function.
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*
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* @param[in] dev device descriptor
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* @param[in] input selected input - 0 for CIN1, 1 for CIN2
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*
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* @return AD7746_OK on success
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* @return AD7746_NOI2C on error
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*/
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int ad7746_set_cap_ch_input(const ad7746_t *dev, ad7746_cap_input_t input);
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/**
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* @brief Sets the mode for the voltage / temperature channel and updates the
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* descriptor with the new configuration. If not configured manually,
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the driver sets the correct mode within the dedicated read function.
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*
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* @param[in, out] dev device descriptor
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* @param[in] mode mode to which the channel has to be set
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*
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* @return AD7746_OK on success
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* @return AD7746_NOI2C on error
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*/
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int ad7746_set_vt_ch_mode(ad7746_t *dev, ad7746_vt_mode_t mode);
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/**
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* @brief Sets the sample rate for the voltage / temperature channel
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*
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* @param[in] dev device descriptor
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* @param[in] sr sample rate
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*
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* @return AD7746_OK on success
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* @return AD7746_NOI2C on error
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*/
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int ad7746_set_vt_sr(const ad7746_t *dev, ad7746_vt_sample_rate_t sr);
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/**
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* @brief Sets the sample rate for the capacitance channel
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*
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* @param[in] dev device descriptor
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* @param[in] sr sample rate
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*
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* @return AD7746_OK on success
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* @return AD7746_NOI2C on error
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*/
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int ad7746_set_cap_sr(const ad7746_t *dev, ad7746_cap_sample_rate_t sr);
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#ifdef __cplusplus
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}
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#endif
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#endif /* AD7746_H */
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/** @} */
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