Particle-OneWire.cpp

#include "Particle-OneWire.h"
#include "application.h"

OneWire::OneWire(uint16_t pin){
    pinMode(pin, INPUT);

    _pin = pin;
}

// Perform the onewire reset function.  We will wait up to 250uS for
// the bus to come high, if it doesn't then it is broken or shorted
// and we return a 0;
//
// Returns 1 if a device asserted a presence pulse, 0 otherwise.
//
uint8_t OneWire::reset(void){
    uint8_t r;
    uint8_t retries = 125;

    noInterrupts();
    pinModeFastInput();
    interrupts();
    // wait until the wire is high... just in case
    do {
        if (--retries == 0) return 0;

        HAL_Delay_Microseconds(2);
    } while ( !digitalReadFast());

    noInterrupts();

    digitalWriteFastLow();
    pinModeFastOutput();   // drive output low

    interrupts();
    HAL_Delay_Microseconds(480);
    noInterrupts();

    pinModeFastInput();    // allow it to float

    HAL_Delay_Microseconds(70);

    r =! digitalReadFast();

    interrupts();

    HAL_Delay_Microseconds(410);

    return r;
}

void OneWire::write_bit(uint8_t v){
    if (v & 1) {
      //Serial1.println("In v & 1, write_bit.");
        noInterrupts();

        digitalWriteFastLow();
        pinModeFastOutput();   // drive output low

        HAL_Delay_Microseconds(10);

        digitalWriteFastHigh();    // drive output high

        interrupts();

        HAL_Delay_Microseconds(55);
    } else {
      //Serial1.println("In else, write_bit.");
        noInterrupts();

        digitalWriteFastLow();
        pinModeFastOutput();   // drive output low

        HAL_Delay_Microseconds(65);

        digitalWriteFastHigh();    // drive output high

        interrupts();

        HAL_Delay_Microseconds(5);
    }
}

//
// Read a bit. Port and bit is used to cut lookup time and provide
// more certain timing.
//
uint8_t OneWire::read_bit(void){
    uint8_t r;

    noInterrupts();

    pinModeFastOutput();
    digitalWriteFastLow();

    HAL_Delay_Microseconds(3);

    pinModeFastInput();    // let pin float, pull up will raise

    HAL_Delay_Microseconds(10);

    r = digitalReadFast();

    interrupts();
    HAL_Delay_Microseconds(53);

    return r;
}

//
// Write a byte. The writing code uses the active drivers to raise the
// pin high, if you need power after the write (e.g. DS18S20 in
// parasite power mode) then set 'power' to 1, otherwise the pin will
// go tri-state at the end of the write to avoid heating in a short or
// other mishap.
//
void OneWire::write(uint8_t v, uint8_t power) {
    uint8_t bitMask;

    for (bitMask = 0x01; bitMask; bitMask <<= 1) {
        OneWire::write_bit( (bitMask & v)?1:0);
    }

    if ( !power) {
        noInterrupts();

        pinModeFastInput();
        digitalWriteFastLow();

        interrupts();
    }
}

void OneWire::write_bytes(const uint8_t *buf, uint16_t count, bool power) {
    for (uint16_t i = 0 ; i < count ; i++)
        write(buf[i]);

    if (!power) {
        noInterrupts();

        pinModeFastInput();
        digitalWriteFastLow();

        interrupts();
    }
}

//
// Read a byte
//
uint8_t OneWire::read() {
    uint8_t bitMask;
    uint8_t r = 0;

    for (bitMask = 0x01; bitMask; bitMask <<= 1) {
        if ( OneWire::read_bit()) r |= bitMask;
    }

    return r;
}

void OneWire::read_bytes(uint8_t *buf, uint16_t count) {
    for (uint16_t i = 0 ; i < count ; i++)
        buf[i] = read();
}

//
// Do a ROM select
//
void OneWire::select(const uint8_t rom[8]){
    uint8_t i;

    write(0x55);           // Choose ROM

    for (i = 0; i < 8; i++) write(rom[i]);
}

//
// Do a ROM skip
//
void OneWire::skip(){
    write(0xCC);           // Skip ROM
}

void OneWire::depower(){
    noInterrupts();

    pinModeFastInput();

    interrupts();
}

#if ONEWIRE_SEARCH

//
// You need to use this function to start a search again from the beginning.
// You do not need to do it for the first search, though you could.
//
void OneWire::reset_search(){
    // reset the search state
    LastDiscrepancy = 0;
    LastDeviceFlag = FALSE;
    LastFamilyDiscrepancy = 0;

    for(int i = 7; ; i--) {
        ROM_NO[i] = 0;
        if ( i == 0) break;
    }
}

// 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 family_code){
   // set the search state to find SearchFamily type devices

   ROM_NO[0] = family_code;

   for (uint8_t i = 1; i < 8; i++)
      ROM_NO[i] = 0;

   LastDiscrepancy = 64;
   LastFamilyDiscrepancy = 0;
   LastDeviceFlag = FALSE;
}

//
// Perform a search. If this function returns a '1' then it has
// enumerated the next device and you may retrieve the ROM from the
// OneWire::address variable. If there are no devices, no further
// devices, or something horrible happens in the middle of the
// enumeration then a 0 is returned.  If a new device is found then
// its address is copied to newAddr.  Use OneWire::reset_search() to
// start over.
//
// --- Replaced by the one from the Dallas Semiconductor web site ---
//--------------------------------------------------------------------------
// Perform the 1-Wire Search Algorithm on the 1-Wire bus using the existing
// search state.
// Return TRUE  : device found, ROM number in ROM_NO buffer
//        FALSE : device not found, end of search
//
uint8_t OneWire::search(uint8_t *newAddr){
    uint8_t id_bit_number;
    uint8_t last_zero, rom_byte_number, search_result;
    uint8_t id_bit, cmp_id_bit;

    unsigned char rom_byte_mask, search_direction;

    // initialize for search
    id_bit_number = 1;
    last_zero = 0;
    rom_byte_number = 0;
    rom_byte_mask = 1;
    search_result = 0;

    // if the last call was not the last one
    if (!LastDeviceFlag)
    {
        // 1-Wire reset
        if (!reset()){
            // reset the search
            LastDiscrepancy = 0;
            LastDeviceFlag = FALSE;
            LastFamilyDiscrepancy = 0;

            return FALSE;
        }

        // issue the search command
        write(0xF0);

        // loop to do the search
        do
        {
            // read a bit and its complement
            id_bit = read_bit();
            cmp_id_bit = read_bit();

            // check for no devices on 1-wire
            if ((id_bit == 1) && (cmp_id_bit == 1)){
                break;
            }
            else
            {
                // all devices coupled have 0 or 1
                if (id_bit != cmp_id_bit){
                    search_direction = id_bit;  // bit write value for search
                }
                else{
                    // if this discrepancy if before the Last Discrepancy
                    // on a previous next then pick the same as last time
                    if (id_bit_number < LastDiscrepancy)
                        search_direction = ((ROM_NO[rom_byte_number] & rom_byte_mask) > 0);
                    else
                        // if equal to last pick 1, if not then pick 0
                        search_direction = (id_bit_number == LastDiscrepancy);

                    // if 0 was picked then record its position in LastZero
                    if (search_direction == 0){
                        last_zero = id_bit_number;

                        // check for Last discrepancy in family
                        if (last_zero < 9)
                            LastFamilyDiscrepancy = last_zero;
                    }
                }

                // set or clear the bit in the ROM byte rom_byte_number
                // with mask rom_byte_mask
                if (search_direction == 1)
                  ROM_NO[rom_byte_number] |= rom_byte_mask;
                else
                  ROM_NO[rom_byte_number] &= ~rom_byte_mask;

                // serial number search direction write bit
                write_bit(search_direction);

                // increment the byte counter id_bit_number
                // and shift the mask rom_byte_mask
                id_bit_number++;
                rom_byte_mask <<= 1;

                // if the mask is 0 then go to new SerialNum byte rom_byte_number and reset mask
                if (rom_byte_mask == 0)
                {
                    rom_byte_number++;
                    rom_byte_mask = 1;
                }
            }
        }while(rom_byte_number < 8);  // loop until through all ROM bytes 0-7

        // if the search was successful then
        if (!(id_bit_number < 65))
        {
            // search successful so set LastDiscrepancy,LastDeviceFlag,search_result
            LastDiscrepancy = last_zero;

            // check for last device
            if (LastDiscrepancy == 0)
                LastDeviceFlag = TRUE;

            search_result = TRUE;
        }
    }

    // if no device found then reset counters so next 'search' will be like a first
    if (!search_result || !ROM_NO[0]){
        LastDiscrepancy = 0;
        LastDeviceFlag = FALSE;
        LastFamilyDiscrepancy = 0;
        search_result = FALSE;
    }

    for (int i = 0; i < 8; i++) newAddr[i] = ROM_NO[i];

    return search_result;
}

#endif

#if ONEWIRE_CRC
// The 1-Wire CRC scheme is described in Maxim Application Note 27:
// "Understanding and Using Cyclic Redundancy Checks with Maxim iButton Products"
//


//
// Compute a Dallas Semiconductor 8 bit CRC directly.
// this is much slower, but much smaller, than the lookup table.
//
uint8_t OneWire::crc8( uint8_t *addr, uint8_t len){
    uint8_t crc = 0;

    while (len--) {
        uint8_t inbyte = *addr++;
        for (uint8_t i = 8; i; i--) {
            uint8_t mix = (crc ^ inbyte) & 0x01;
            crc >>= 1;
            if (mix) crc ^= 0x8C;
                inbyte >>= 1;
        }
    }

    return crc;
}
#endif

#if ONEWIRE_CRC16
bool OneWire::check_crc16(const uint8_t* input, uint16_t len, const uint8_t* inverted_crc, uint16_t crc){
    crc = ~crc16(input, len, crc);

    return (crc & 0xFF) == inverted_crc[0] && (crc >> 8) == inverted_crc[1];
}

uint16_t OneWire::crc16(const uint8_t* input, uint16_t len, uint16_t crc){
    static const uint8_t oddparity[16] =
        { 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0 };

    for (uint16_t i = 0 ; i < len ; i++) {
        // Even though we're just copying a byte from the input,
        // we'll be doing 16-bit computation with it.
        uint16_t cdata = input[i];
        cdata = (cdata ^ crc) & 0xff;
        crc >>= 8;

        if (oddparity[cdata & 0x0F] ^ oddparity[cdata >> 4])
            crc ^= 0xC001;

        cdata <<= 6;
        crc ^= cdata;
        cdata <<= 1;
        crc ^= cdata;
    }

    return crc;
}
#endif