197 lines
7.8 KiB
C
197 lines
7.8 KiB
C
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/*
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* MIT License
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*
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* Copyright (c) 2017 David Antliff
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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/**
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* @file ds18b20.h
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* @brief Interface definitions for the Maxim Integrated DS18B20 Programmable
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* Resolution 1-Wire Digital Thermometer device.
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*
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* This component provides structures and functions that are useful for communicating
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* with DS18B20 devices connected via a Maxim Integrated 1-Wire® bus.
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*/
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#ifndef DS18B20_H
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#define DS18B20_H
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#include "owb.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* @brief Success and error codes.
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*/
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typedef enum
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{
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DS18B20_ERROR_UNKNOWN = -1,
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DS18B20_OK = 0,
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DS18B20_ERROR_DEVICE, ///< A device error occurred
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DS18B20_ERROR_CRC, ///< A CRC error occurred
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DS18B20_ERROR_OWB, ///< A One Wire Bus error occurred
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DS18B20_ERROR_NULL, ///< A parameter or value is NULL
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} DS18B20_ERROR;
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/**
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* @brief Symbols for the supported temperature resolution of the device.
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*/
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typedef enum
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{
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DS18B20_RESOLUTION_INVALID = -1, ///< Invalid resolution
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DS18B20_RESOLUTION_9_BIT = 9, ///< 9-bit resolution, LSB bits 2,1,0 undefined
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DS18B20_RESOLUTION_10_BIT = 10, ///< 10-bit resolution, LSB bits 1,0 undefined
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DS18B20_RESOLUTION_11_BIT = 11, ///< 11-bit resolution, LSB bit 0 undefined
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DS18B20_RESOLUTION_12_BIT = 12, ///< 12-bit resolution (default)
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} DS18B20_RESOLUTION;
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/**
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* @brief Structure containing information related to a single DS18B20 device connected
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* via a 1-Wire bus.
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*/
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typedef struct
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{
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bool init; ///< True if struct has been initialised, otherwise false
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bool solo; ///< True if device is intended to be the only one connected to the bus, otherwise false
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bool use_crc; ///< True if CRC checks are to be used when retrieving information from a device on the bus
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const OneWireBus * bus; ///< Pointer to 1-Wire bus information relevant to this device
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OneWireBus_ROMCode rom_code; ///< The ROM code used to address this device on the bus
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DS18B20_RESOLUTION resolution; ///< Temperature measurement resolution per reading
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} DS18B20_Info;
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/**
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* @brief Construct a new device info instance.
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* New instance should be initialised before calling other functions.
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* @return Pointer to new device info instance, or NULL if it cannot be created.
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*/
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DS18B20_Info * ds18b20_malloc(void);
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/**
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* @brief Delete an existing device info instance.
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* @param[in] ds18b20_info Pointer to device info instance.
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* @param[in,out] ds18b20_info Pointer to device info instance that will be freed and set to NULL.
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*/
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void ds18b20_free(DS18B20_Info ** ds18b20_info);
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/**
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* @brief Initialise a device info instance with the specified GPIO.
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* @param[in] ds18b20_info Pointer to device info instance.
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* @param[in] bus Pointer to initialised 1-Wire bus instance.
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* @param[in] rom_code Device-specific ROM code to identify a device on the bus.
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*/
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void ds18b20_init(DS18B20_Info * ds18b20_info, const OneWireBus * bus, OneWireBus_ROMCode rom_code);
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/**
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* @brief Initialise a device info instance with the specified GPIO as a solo device on the bus.
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*
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* This is subject to the requirement that this device is the ONLY device on the bus.
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* This allows for faster commands to be used without ROM code addressing.
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*
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* NOTE: if additional devices are added to the bus, operation will cease to work correctly.
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*
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* @param[in] ds18b20_info Pointer to device info instance.
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* @param[in] bus Pointer to initialised 1-Wire bus instance.
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* @param[in] rom_code Device-specific ROM code to identify a device on the bus.
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*/
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void ds18b20_init_solo(DS18B20_Info * ds18b20_info, const OneWireBus * bus);
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/**
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* @brief Enable or disable use of CRC checks on device communications.
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* @param[in] ds18b20_info Pointer to device info instance.
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* @param[in] use_crc True to enable CRC checks, false to disable.
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*/
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void ds18b20_use_crc(DS18B20_Info * ds18b20_info, bool use_crc);
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/**
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* @brief Set temperature measurement resolution.
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*
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* This programs the hardware to the specified resolution and sets the cached value to be the same.
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* If the program fails, the value currently in hardware is used to refresh the cache.
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*
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* @param[in] ds18b20_info Pointer to device info instance.
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* @param[in] resolution Selected resolution.
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* @return True if successful, otherwise false.
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*/
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bool ds18b20_set_resolution(DS18B20_Info * ds18b20_info, DS18B20_RESOLUTION resolution);
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/**
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* @brief Update and return the current temperature measurement resolution from the device.
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* @param[in] ds18b20_info Pointer to device info instance.
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* @return The currently configured temperature measurement resolution.
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*/
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DS18B20_RESOLUTION ds18b20_read_resolution(DS18B20_Info * ds18b20_info);
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/**
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* @brief Read 64-bit ROM code from device - only works when there is a single device on the bus.
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* @param[in] ds18b20_info Pointer to device info instance.
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* @return The 64-bit value read from the device's ROM.
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*/
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OneWireBus_ROMCode ds18b20_read_rom(DS18B20_Info * ds18b20_info);
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/**
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* @brief Start a temperature measurement conversion on a single device.
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* @param[in] ds18b20_info Pointer to device info instance.
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*/
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bool ds18b20_convert(const DS18B20_Info * ds18b20_info);
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/**
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* @brief Start temperature conversion on all connected devices.
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*
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* This should be followed by a sufficient delay to ensure all devices complete
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* their conversion before the measurements are read.
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* @param[in] bus Pointer to initialised bus instance.
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*/
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void ds18b20_convert_all(const OneWireBus * bus);
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/**
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* @brief Wait for the maximum conversion time according to the current resolution of the device.
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* @param[in] bus Pointer to initialised bus instance.
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* @return An estimate of the time elapsed, in milliseconds. Actual elapsed time may be greater.
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*/
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float ds18b20_wait_for_conversion(const DS18B20_Info * ds18b20_info);
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/**
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* @brief Read last temperature measurement from device.
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*
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* This is typically called after ds18b20_start_mass_conversion(), provided enough time
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* has elapsed to ensure that all devices have completed their conversions.
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* @param[in] ds18b20_info Pointer to device info instance. Must be initialised first.
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* @param[out] value Pointer to the measurement value returned by the device, in degrees Celsius.
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* @return DS18B20_OK if read is successful, otherwise error.
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*/
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DS18B20_ERROR ds18b20_read_temp(const DS18B20_Info * ds18b20_info, float * value);
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/**
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* @brief Convert, wait and read current temperature from device.
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* @param[in] ds18b20_info Pointer to device info instance. Must be initialised first.
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* @param[out] value Pointer to the measurement value returned by the device, in degrees Celsius.
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* @return DS18B20_OK if read is successful, otherwise error.
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*/
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DS18B20_ERROR ds18b20_convert_and_read_temp(const DS18B20_Info * ds18b20_info, float * value);
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#ifdef __cplusplus
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}
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#endif
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#endif // DS18B20_H
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