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135 lines
3.9 KiB
135 lines
3.9 KiB
#ifndef ONE_WIRE_BUS_H
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#define ONE_WIRE_BUS_H
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#include <stdint.h>
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#include <stdbool.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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// ROM commands
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#define OWB_ROM_SEARCH 0xF0
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#define OWB_ROM_READ 0x33
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#define OWB_ROM_MATCH 0x55
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#define OWB_ROM_SKIP 0xCC
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#define OWB_ROM_SEARCH_ALARM 0xEC
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typedef struct _OneWireBus OneWireBus;
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typedef uint64_t OneWireBusROMCode;
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/**
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* @brief Construct a new 1-Wire bus instance.
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* New instance should be initialised before calling other functions.
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* @return Pointer to new bus instance, or NULL if it cannot be created.
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*/
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OneWireBus * owb_malloc(void);
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/**
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* @brief Delete an existing device info instance.
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* @param[in] bus Pointer to bus 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 owb_free(OneWireBus ** bus);
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/**
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* @brief Initialise a 1-Wire bus instance with the specified GPIO.
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* @param[in] bus Pointer to bus instance.
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* @param[in] gpio GPIO number to associate with device.
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*/
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void owb_init(OneWireBus * bus, int gpio);
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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] bus Pointer to initialised bus 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 owb_use_crc(OneWireBus * bus, bool use_crc);
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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] bus Pointer to initialised bus instance.
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* @return The 64-bit value read from the device's ROM.
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*/
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uint64_t owb_read_rom(const OneWireBus * bus);
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// TODO
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bool owb_verify_rom(const OneWireBus * bus, uint64_t rom_code);
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/**
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* @brief Reset the 1-Wire bus.
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* @param[in] bus Pointer to initialised bus instance.
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* @return True if at least one device is present on the bus.
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*/
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bool owb_reset(const OneWireBus * bus);
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/**
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* @brief Write a single byte to the 1-Wire bus.
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* @param[in] bus Pointer to initialised bus instance.
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* @param[in] data Byte value to write to bus.
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*/
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void owb_write_byte(const OneWireBus * bus, uint8_t data);
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/**
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* @brief Read a single byte from the 1-Wire bus.
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* @param[in] bus Pointer to initialised bus instance.
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* @return The byte value read from the bus.
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*/
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uint8_t owb_read_byte(const OneWireBus * bus);
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/**
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* @brief Read a number of bytes from the 1-Wire bus.
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* @param[in] bus Pointer to initialised bus instance.
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* @param[in, out] buffer Pointer to buffer to receive read data.
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* @param[in] len Number of bytes to read, must not exceed length of receive buffer.
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* @return Pointer to receive buffer.
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*/
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uint8_t * owb_read_bytes(const OneWireBus * bus, uint8_t * buffer, unsigned int len);
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/**
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* @brief Write a number of bytes to the 1-Wire bus.
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* @param[in] bus Pointer to initialised bus instance.
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* @param[in] buffer Pointer to buffer to write data from.
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* @param[in] len Number of bytes to write.
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* @return Pointer to write buffer.
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*/
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const uint8_t * owb_write_bytes(const OneWireBus * bus, const uint8_t * buffer, unsigned int len);
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/**
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* @brief Write a ROM code to the 1-Wire bus ensuring LSB is sent first.
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* @param[in] bus Pointer to initialised bus instance.
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* @param[in] rom_code ROM code to write to bus.
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*/
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void owb_write_rom_code(const OneWireBus * bus, uint64_t rom_code);
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/**
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* @brief 1-Wire 8-bit CRC lookup.
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* @param[in] crc Starting CRC value. Pass in prior CRC to accumulate.
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* @param[in] data Byte to feed into CRC.
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* @return Resultant CRC value.
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*/
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uint8_t owb_crc8(uint8_t crc, uint8_t data);
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// Search API
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struct OneWireBus_SearchState
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{
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uint8_t rom_code[8];
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int last_discrepancy;
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int last_family_discrepancy;
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int last_device_flag;
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};
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typedef struct OneWireBus_SearchState OneWireBus_SearchState;
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bool owb_search_first(const OneWireBus * bus, OneWireBus_SearchState * state);
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bool owb_search_next(const OneWireBus * bus, OneWireBus_SearchState * state);
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#ifdef __cplusplus
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}
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#endif
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#endif // ONE_WIRE_BUS_H
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