Public for testMax31820
Fork of OneWire by
OneWire.h
- Committer:
- hudakz
- Date:
- 2015-03-15
- Revision:
- 0:acf75feb0947
File content as of revision 0:acf75feb0947:
#ifndef OneWire_h #define OneWire_h #include <inttypes.h> #include <mbed.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 class OneWire { private: DigitalInOut wire; #if ONEWIRE_SEARCH // global search state unsigned char ROM_NO[8]; uint8_t LastDiscrepancy; uint8_t LastFamilyDiscrepancy; uint8_t LastDeviceFlag; #endif public: OneWire(PinName 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 reset(void); // Issue a 1-Wire rom select command, you do the reset first. void select(const uint8_t rom[8]); // Issue a 1-Wire rom skip command, to address all on bus. void skip(void); // 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 write(uint8_t v, uint8_t power = 0); void write_bytes(const uint8_t *buf, uint16_t count, bool power = 0); // Read a byte. uint8_t read(void); void read_bytes(uint8_t *buf, uint16_t count); // Write a bit. The bus is always left powered at the end, see // note in write() about that. void write_bit(uint8_t v); // Read a bit. uint8_t read_bit(void); // 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 depower(void); #if ONEWIRE_SEARCH // Clear the search state so that if will start from the beginning again. void reset_search(); // Setup the search to find the device type 'family_code' on the next call // to search(*newAddr) if it is present. void target_search(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 search(uint8_t *newAddr); #endif #if ONEWIRE_CRC // Compute a Dallas Semiconductor 8 bit CRC, these are used in the // ROM and scratchpad registers. static uint8_t 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. static bool check_crc16(const uint8_t* input, uint16_t len, const uint8_t* inverted_crc, uint16_t crc = 0); // 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. static uint16_t crc16(const uint8_t* input, uint16_t len, uint16_t crc = 0); #endif #endif }; #endif