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- #ifndef __ONEWIRE_H__
- #define __ONEWIRE_H__
- #include <stdint.h>
- #include <stdbool.h>
- // You can exclude certain features from OneWire. In theory, this
- // might save some space. In practice, the compiler automatically
- // removes unused code (technically, the linker, using -fdata-sections
- // and -ffunction-sections when compiling, and Wl,--gc-sections
- // when linking), so most of these will not result in any code size
- // reduction. Well, unless you try to use the missing features
- // and redesign your program to not need them! ONEWIRE_CRC8_TABLE
- // is the exception, because it selects a fast but large algorithm
- // or a small but slow algorithm.
- // you can exclude onewire_search by defining that to 0
- #ifndef ONEWIRE_SEARCH
- #define ONEWIRE_SEARCH 1
- #endif
- // You can exclude CRC checks altogether by defining this to 0
- #ifndef ONEWIRE_CRC
- #define ONEWIRE_CRC 1
- #endif
- // Select the table-lookup method of computing the 8-bit CRC
- // by setting this to 1. The lookup table enlarges code size by
- // about 250 bytes. It does NOT consume RAM (but did in very
- // old versions of OneWire). If you disable this, a slower
- // but very compact algorithm is used.
- #ifndef ONEWIRE_CRC8_TABLE
- #define ONEWIRE_CRC8_TABLE 0
- #endif
- // You can allow 16-bit CRC checks by defining this to 1
- // (Note that ONEWIRE_CRC must also be 1.)
- #ifndef ONEWIRE_CRC16
- #define ONEWIRE_CRC16 1
- #endif
- // Platform specific I/O definitions
- #define DIRECT_READ(pin) (0x1 & GPIO_INPUT_GET(GPIO_ID_PIN(pin_num[pin])))
- #define DIRECT_MODE_INPUT(pin) GPIO_DIS_OUTPUT(GPIO_ID_PIN(pin_num[pin]))
- #define DIRECT_MODE_OUTPUT(pin)
- #define DIRECT_WRITE_LOW(pin) (GPIO_OUTPUT_SET(GPIO_ID_PIN(pin_num[pin]), 0))
- #define DIRECT_WRITE_HIGH(pin) (GPIO_OUTPUT_SET(GPIO_ID_PIN(pin_num[pin]), 1))
- void onewire_init(uint8_t pin);
- // Perform a 1-Wire reset cycle. Returns 1 if a device responds
- // with a presence pulse. Returns 0 if there is no device or the
- // bus is shorted or otherwise held low for more than 250uS
- uint8_t onewire_reset(uint8_t pin);
- // Issue a 1-Wire rom select command, you do the reset first.
- void onewire_select(uint8_t pin, const uint8_t rom[8]);
- // Issue a 1-Wire rom skip command, to address all on bus.
- void onewire_skip(uint8_t pin);
- // Write a byte. If 'power' is one then the wire is held high at
- // the end for parasitically powered devices. You are responsible
- // for eventually depowering it by calling depower() or doing
- // another read or write.
- void onewire_write(uint8_t pin, uint8_t v, uint8_t power);
- void onewire_write_bytes(uint8_t pin, const uint8_t *buf, uint16_t count, bool power);
- // Read a byte.
- uint8_t onewire_read(uint8_t pin);
- void onewire_read_bytes(uint8_t pin, uint8_t *buf, uint16_t count);
- // Write a bit. The bus is always left powered at the end, see
- // note in write() about that.
- static void onewire_write_bit(uint8_t pin, uint8_t v, uint8_t power);
- // Read a bit.
- static uint8_t onewire_read_bit(uint8_t pin);
- // Stop forcing power onto the bus. You only need to do this if
- // you used the 'power' flag to write() or used a write_bit() call
- // and aren't about to do another read or write. You would rather
- // not leave this powered if you don't have to, just in case
- // someone shorts your bus.
- void onewire_depower(uint8_t pin);
- #if ONEWIRE_SEARCH
- // Clear the search state so that if will start from the beginning again.
- void onewire_reset_search(uint8_t pin);
- // Setup the search to find the device type 'family_code' on the next call
- // to search(*newAddr) if it is present.
- void onewire_target_search(uint8_t pin, uint8_t family_code);
- // Look for the next device. Returns 1 if a new address has been
- // returned. A zero might mean that the bus is shorted, there are
- // no devices, or you have already retrieved all of them. It
- // might be a good idea to check the CRC to make sure you didn't
- // get garbage. The order is deterministic. You will always get
- // the same devices in the same order.
- uint8_t onewire_search(uint8_t pin, uint8_t *newAddr);
- #endif
- #if ONEWIRE_CRC
- // Compute a Dallas Semiconductor 8 bit CRC, these are used in the
- // ROM and scratchpad registers.
- uint8_t onewire_crc8(const uint8_t *addr, uint8_t len);
- #if ONEWIRE_CRC16
- // Compute the 1-Wire CRC16 and compare it against the received CRC.
- // Example usage (reading a DS2408):
- // // Put everything in a buffer so we can compute the CRC easily.
- // uint8_t buf[13];
- // buf[0] = 0xF0; // Read PIO Registers
- // buf[1] = 0x88; // LSB address
- // buf[2] = 0x00; // MSB address
- // WriteBytes(net, buf, 3); // Write 3 cmd bytes
- // ReadBytes(net, buf+3, 10); // Read 6 data bytes, 2 0xFF, 2 CRC16
- // if (!CheckCRC16(buf, 11, &buf[11])) {
- // // Handle error.
- // }
- //
- // @param input - Array of bytes to checksum.
- // @param len - How many bytes to use.
- // @param inverted_crc - The two CRC16 bytes in the received data.
- // This should just point into the received data,
- // *not* at a 16-bit integer.
- // @param crc - The crc starting value (optional)
- // @return True, iff the CRC matches.
- bool onewire_check_crc16(const uint8_t* input, uint16_t len, const uint8_t* inverted_crc, uint16_t crc);
- // Compute a Dallas Semiconductor 16 bit CRC. This is required to check
- // the integrity of data received from many 1-Wire devices. Note that the
- // CRC computed here is *not* what you'll get from the 1-Wire network,
- // for two reasons:
- // 1) The CRC is transmitted bitwise inverted.
- // 2) Depending on the endian-ness of your processor, the binary
- // representation of the two-byte return value may have a different
- // byte order than the two bytes you get from 1-Wire.
- // @param input - Array of bytes to checksum.
- // @param len - How many bytes to use.
- // @param crc - The crc starting value (optional)
- // @return The CRC16, as defined by Dallas Semiconductor.
- uint16_t onewire_crc16(const uint8_t* input, uint16_t len, uint16_t crc);
- #endif
- #endif
- #endif
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