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Diffstat (limited to 'sw/lib/OneWire/OneWire.h')
| -rw-r--r-- | sw/lib/OneWire/OneWire.h | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/sw/lib/OneWire/OneWire.h b/sw/lib/OneWire/OneWire.h new file mode 100644 index 0000000..a7bfab7 --- /dev/null +++ b/sw/lib/OneWire/OneWire.h @@ -0,0 +1,182 @@ +#ifndef OneWire_h +#define OneWire_h + +#ifdef __cplusplus + +#include <stdint.h> + +#if defined(__AVR__) +#include <util/crc16.h> +#endif + +#if ARDUINO >= 100 +#include <Arduino.h> // for delayMicroseconds, digitalPinToBitMask, etc +#else +#include "WProgram.h" // for delayMicroseconds +#include "pins_arduino.h" // for digitalPinToBitMask, etc +#endif + +// 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 1 +#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 + +// Board-specific macros for direct GPIO +#include "util/OneWire_direct_regtype.h" + +class OneWire +{ + private: + IO_REG_TYPE bitmask; + volatile IO_REG_TYPE *baseReg; + +#if ONEWIRE_SEARCH + // global search state + unsigned char ROM_NO[8]; + uint8_t LastDiscrepancy; + uint8_t LastFamilyDiscrepancy; + bool LastDeviceFlag; +#endif + + public: + OneWire() { } + OneWire(uint8_t pin) { begin(pin); } + void begin(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 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. + bool search(uint8_t *newAddr, bool search_mode = true); +#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 +}; + +// Prevent this name from leaking into Arduino sketches +#ifdef IO_REG_TYPE +#undef IO_REG_TYPE +#endif + +#endif // __cplusplus +#endif // OneWire_h |