Zoltan Hudak / OneWire

Dallas' 1-Wire bus protocol library

Dependents:   DS1825 DISCO-F746-Dessiccateur-V1 watersenor_and_temp_code DS1820 ... more

OneWire.h@9:4af0015b0f47, 2019-01-26 (annotated)

Committer:
hudakz
Date:
Sat Jan 26 21:21:27 2019 +0000
Revision:
9:4af0015b0f47
Parent:
6:d6e084297fb9
Child:
10:c89b9ad6097c
STM related parts optimized.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hudakz 0:acf75feb0947 1 #ifndef OneWire_h
hudakz 0:acf75feb0947 2 #define OneWire_h
hudakz 0:acf75feb0947 3
hudakz 0:acf75feb0947 4 #include <inttypes.h>
hudakz 0:acf75feb0947 5 #include <mbed.h>
hudakz 0:acf75feb0947 6
hudakz 0:acf75feb0947 7 // You can exclude certain features from OneWire. In theory, this
hudakz 0:acf75feb0947 8 // might save some space. In practice, the compiler automatically
hudakz 0:acf75feb0947 9 // removes unused code (technically, the linker, using -fdata-sections
hudakz 0:acf75feb0947 10 // and -ffunction-sections when compiling, and Wl,--gc-sections
hudakz 0:acf75feb0947 11 // when linking), so most of these will not result in any code size
hudakz 0:acf75feb0947 12 // reduction. Well, unless you try to use the missing features
hudakz 0:acf75feb0947 13 // and redesign your program to not need them! ONEWIRE_CRC8_TABLE
hudakz 0:acf75feb0947 14 // is the exception, because it selects a fast but large algorithm
hudakz 0:acf75feb0947 15 // or a small but slow algorithm.
hudakz 0:acf75feb0947 16
hudakz 0:acf75feb0947 17 // you can exclude onewire_search by defining that to 0
hudakz 0:acf75feb0947 18 #ifndef ONEWIRE_SEARCH
hudakz 0:acf75feb0947 19 #define ONEWIRE_SEARCH 1
hudakz 0:acf75feb0947 20 #endif
hudakz 0:acf75feb0947 21
hudakz 0:acf75feb0947 22 // You can exclude CRC checks altogether by defining this to 0
hudakz 0:acf75feb0947 23 #ifndef ONEWIRE_CRC
hudakz 0:acf75feb0947 24 #define ONEWIRE_CRC 1
hudakz 0:acf75feb0947 25 #endif
hudakz 0:acf75feb0947 26
hudakz 9:4af0015b0f47 27 class OneWire : public DigitalInOut
hudakz 0:acf75feb0947 28 {
hudakz 9:4af0015b0f47 29 Timer timer;
hudakz 0:acf75feb0947 30
hudakz 0:acf75feb0947 31 #if ONEWIRE_SEARCH
hudakz 0:acf75feb0947 32 // global search state
hudakz 0:acf75feb0947 33 unsigned char ROM_NO[8];
hudakz 0:acf75feb0947 34 uint8_t LastDiscrepancy;
hudakz 0:acf75feb0947 35 uint8_t LastFamilyDiscrepancy;
hudakz 0:acf75feb0947 36 uint8_t LastDeviceFlag;
hudakz 0:acf75feb0947 37 #endif
hudakz 0:acf75feb0947 38
hudakz 9:4af0015b0f47 39 public:
hudakz 0:acf75feb0947 40 OneWire(PinName pin);
hudakz 0:acf75feb0947 41
hudakz 0:acf75feb0947 42 // Perform a 1-Wire reset cycle. Returns 1 if a device responds
hudakz 0:acf75feb0947 43 // with a presence pulse. Returns 0 if there is no device or the
hudakz 0:acf75feb0947 44 // bus is shorted or otherwise held low for more than 250uS
hudakz 0:acf75feb0947 45 uint8_t reset(void);
hudakz 0:acf75feb0947 46
hudakz 0:acf75feb0947 47 // Issue a 1-Wire rom select command, you do the reset first.
hudakz 0:acf75feb0947 48 void select(const uint8_t rom[8]);
hudakz 0:acf75feb0947 49
hudakz 0:acf75feb0947 50 // Issue a 1-Wire rom skip command, to address all on bus.
hudakz 0:acf75feb0947 51 void skip(void);
hudakz 0:acf75feb0947 52
hudakz 0:acf75feb0947 53 // Write a byte. If 'power' is one then the wire is held high at
hudakz 0:acf75feb0947 54 // the end for parasitically powered devices. You are responsible
hudakz 0:acf75feb0947 55 // for eventually depowering it by calling depower() or doing
hudakz 0:acf75feb0947 56 // another read or write.
hudakz 9:4af0015b0f47 57 void write_byte(uint8_t v, uint8_t power = 0);
hudakz 0:acf75feb0947 58
hudakz 0:acf75feb0947 59 void write_bytes(const uint8_t *buf, uint16_t count, bool power = 0);
hudakz 0:acf75feb0947 60
hudakz 0:acf75feb0947 61 // Read a byte.
hudakz 9:4af0015b0f47 62 uint8_t read_byte(void);
hudakz 0:acf75feb0947 63
hudakz 0:acf75feb0947 64 void read_bytes(uint8_t *buf, uint16_t count);
hudakz 0:acf75feb0947 65
hudakz 0:acf75feb0947 66 // Write a bit. The bus is always left powered at the end, see
hudakz 0:acf75feb0947 67 // note in write() about that.
hudakz 0:acf75feb0947 68 void write_bit(uint8_t v);
hudakz 0:acf75feb0947 69
hudakz 0:acf75feb0947 70 // Read a bit.
hudakz 0:acf75feb0947 71 uint8_t read_bit(void);
hudakz 0:acf75feb0947 72
hudakz 0:acf75feb0947 73 // Stop forcing power onto the bus. You only need to do this if
hudakz 0:acf75feb0947 74 // you used the 'power' flag to write() or used a write_bit() call
hudakz 0:acf75feb0947 75 // and aren't about to do another read or write. You would rather
hudakz 0:acf75feb0947 76 // not leave this powered if you don't have to, just in case
hudakz 0:acf75feb0947 77 // someone shorts your bus.
hudakz 0:acf75feb0947 78 void depower(void);
hudakz 0:acf75feb0947 79
hudakz 0:acf75feb0947 80 #if ONEWIRE_SEARCH
hudakz 0:acf75feb0947 81 // Clear the search state so that if will start from the beginning again.
hudakz 0:acf75feb0947 82 void reset_search();
hudakz 0:acf75feb0947 83
hudakz 0:acf75feb0947 84 // Setup the search to find the device type 'family_code' on the next call
hudakz 0:acf75feb0947 85 // to search(*newAddr) if it is present.
hudakz 0:acf75feb0947 86 void target_search(uint8_t family_code);
hudakz 0:acf75feb0947 87
hudakz 0:acf75feb0947 88 // Look for the next device. Returns 1 if a new address has been
hudakz 0:acf75feb0947 89 // returned. A zero might mean that the bus is shorted, there are
hudakz 0:acf75feb0947 90 // no devices, or you have already retrieved all of them. It
hudakz 0:acf75feb0947 91 // might be a good idea to check the CRC to make sure you didn't
hudakz 0:acf75feb0947 92 // get garbage. The order is deterministic. You will always get
hudakz 0:acf75feb0947 93 // the same devices in the same order.
hudakz 0:acf75feb0947 94 uint8_t search(uint8_t *newAddr);
hudakz 0:acf75feb0947 95 #endif
hudakz 0:acf75feb0947 96
hudakz 0:acf75feb0947 97 #if ONEWIRE_CRC
hudakz 0:acf75feb0947 98 // Compute a Dallas Semiconductor 8 bit CRC, these are used in the
hudakz 0:acf75feb0947 99 // ROM and scratchpad registers.
hudakz 0:acf75feb0947 100 static uint8_t crc8(const uint8_t *addr, uint8_t len);
hudakz 0:acf75feb0947 101
hudakz 0:acf75feb0947 102 #if ONEWIRE_CRC16
hudakz 0:acf75feb0947 103 // Compute the 1-Wire CRC16 and compare it against the received CRC.
hudakz 0:acf75feb0947 104 // Example usage (reading a DS2408):
hudakz 0:acf75feb0947 105 // // Put everything in a buffer so we can compute the CRC easily.
hudakz 0:acf75feb0947 106 // uint8_t buf[13];
hudakz 0:acf75feb0947 107 // buf[0] = 0xF0; // Read PIO Registers
hudakz 0:acf75feb0947 108 // buf[1] = 0x88; // LSB address
hudakz 0:acf75feb0947 109 // buf[2] = 0x00; // MSB address
hudakz 0:acf75feb0947 110 // WriteBytes(net, buf, 3); // Write 3 cmd bytes
hudakz 0:acf75feb0947 111 // ReadBytes(net, buf+3, 10); // Read 6 data bytes, 2 0xFF, 2 CRC16
hudakz 0:acf75feb0947 112 // if (!CheckCRC16(buf, 11, &buf[11])) {
hudakz 0:acf75feb0947 113 // // Handle error.
hudakz 0:acf75feb0947 114 // }
hudakz 0:acf75feb0947 115 //
hudakz 0:acf75feb0947 116 // @param input - Array of bytes to checksum.
hudakz 0:acf75feb0947 117 // @param len - How many bytes to use.
hudakz 0:acf75feb0947 118 // @param inverted_crc - The two CRC16 bytes in the received data.
hudakz 0:acf75feb0947 119 // This should just point into the received data,
hudakz 0:acf75feb0947 120 // *not* at a 16-bit integer.
hudakz 0:acf75feb0947 121 // @param crc - The crc starting value (optional)
hudakz 0:acf75feb0947 122 // @return True, iff the CRC matches.
hudakz 0:acf75feb0947 123 static bool check_crc16(const uint8_t* input, uint16_t len, const uint8_t* inverted_crc, uint16_t crc = 0);
hudakz 0:acf75feb0947 124
hudakz 0:acf75feb0947 125 // Compute a Dallas Semiconductor 16 bit CRC. This is required to check
hudakz 0:acf75feb0947 126 // the integrity of data received from many 1-Wire devices. Note that the
hudakz 0:acf75feb0947 127 // CRC computed here is *not* what you'll get from the 1-Wire network,
hudakz 0:acf75feb0947 128 // for two reasons:
hudakz 0:acf75feb0947 129 // 1) The CRC is transmitted bitwise inverted.
hudakz 0:acf75feb0947 130 // 2) Depending on the endian-ness of your processor, the binary
hudakz 0:acf75feb0947 131 // representation of the two-byte return value may have a different
hudakz 0:acf75feb0947 132 // byte order than the two bytes you get from 1-Wire.
hudakz 0:acf75feb0947 133 // @param input - Array of bytes to checksum.
hudakz 0:acf75feb0947 134 // @param len - How many bytes to use.
hudakz 0:acf75feb0947 135 // @param crc - The crc starting value (optional)
hudakz 0:acf75feb0947 136 // @return The CRC16, as defined by Dallas Semiconductor.
hudakz 0:acf75feb0947 137 static uint16_t crc16(const uint8_t* input, uint16_t len, uint16_t crc = 0);
hudakz 0:acf75feb0947 138 #endif
hudakz 0:acf75feb0947 139 #endif
hudakz 0:acf75feb0947 140 };
hudakz 0:acf75feb0947 141
hudakz 0:acf75feb0947 142 #endif
hudakz 9:4af0015b0f47 143
hudakz 9:4af0015b0f47 144