#ifndef __ONEWIRE_H__ #define __ONEWIRE_H__ #include #include // 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