Superseded by MaximInterface.

File content as of revision 34:11fffbe98ef9:

#include "DS2465.hpp"
#include "RomId.hpp"
#include "mbed.h"

#define I2C_WRITE 0
#define I2C_READ 1

// DS2465 commands
#define CMD_1WMR   0xF0
#define CMD_WCFG   0xD2
#define CMD_CHSL   0xC3
#define CMD_SRP    0xE1

#define CMD_1WRS   0xB4
#define CMD_1WWB   0xA5
#define CMD_1WRB   0x96
#define CMD_1WSB   0x87
#define CMD_1WT    0x78
#define CMD_1WTB   0x69
#define CMD_1WRF   0xE1
#define CMD_CPS    0x5A
#define CMD_CSS    0x4B
#define CMD_CSAM   0x3C
#define CMD_CSWM   0x2D
#define CMD_CNMS   0x1E
#define CMD_SPR    0x0F

// DS2465 status bits 
#define STATUS_1WB  0x01
#define STATUS_PPD  0x02
#define STATUS_SD   0x04
#define STATUS_LL   0x08
#define STATUS_RST  0x10
#define STATUS_SBR  0x20
#define STATUS_TSB  0x40
#define STATUS_DIR  0x80

static const int I2C_WRITE_OK = 0;


std::uint8_t DS2465::Config::readByte() const
{
  std::uint8_t config = 0;
  if (c1WS)
    config |= 0x08;
  if (cSPU)
    config |= 0x04;
  if (cPDN)
    config |= 0x02;
  if (cAPU)
    config |= 0x01;
  return config;
}

std::uint8_t DS2465::Config::writeByte() const
{
  std::uint8_t config = readByte();
  return ((~config << 4) | config);
}

void DS2465::Config::reset()
{
  c1WS = cSPU = cPDN = false;
  cAPU = true;
}




DS2465::DS2465(I2C & I2C_interface, std::uint8_t I2C_address)
  : m_I2C_interface(I2C_interface), m_I2C_address(I2C_address)
{
  
}




OneWireMaster::CmdResult DS2465::OWInitMaster()
{
  return detect();
}


//--------------------------------------------------------------------------
// Compute Next Master Secret DS2465 
//
// 'swap' - 1 if swapping a page into the computation
// 'page' - page number to swap in
// 'region' - (1) first 1/2 page, (2) second 1/2 page, (3) entire page 
//
// Returns: true write successful
//          false failure to complete read
//
OneWireMaster::CmdResult DS2465::computeNextMasterSecret(bool swap, unsigned int pageNum, PageRegion region)
{
   std::uint8_t command[2] = { CMD_CNMS, (swap ? (0xC8 | (pageNum << 4) | region) : 0xBF) };
   return writeMemory(ADDR_CMD_REG, command, 2);
}

//--------------------------------------------------------------------------
// Compute Write MAC DS2465 
//
// 'regwrite' - true if writing to a register, false if regular memory
// 'swap' - true if swapping a page into the computation
// 'page' - page number to swap in
// 'segment' - segment number if swaping 
//
// Returns: true write successful
//          false failure to complete read
//
OneWireMaster::CmdResult DS2465::computeWriteMac(bool regwrite, bool swap, unsigned int pageNum, unsigned int segmentNum) const
{
   std::uint8_t command[2] = { CMD_CSWM, ((regwrite << 7) | (swap << 6) | (pageNum << 4) | segmentNum) };
   return cWriteMemory(ADDR_CMD_REG, command, 2);
}

//--------------------------------------------------------------------------
// Compute Slave Authentication MAC DS2465 
//
// 'swap' - true if swapping a page into the computation
// 'page' - page number to swap in
// 'region' - (1) first 1/2 page, (2) second 1/2 page, (3) entire page 
//
// Returns: true write successful
//          false failure to complete read
//
OneWireMaster::CmdResult DS2465::computeAuthMac(bool swap, unsigned int pageNum, PageRegion region) const
{
   std::uint8_t command[2] = { CMD_CSAM, (swap ? (0xC8 | (pageNum << 4) | region) : 0xBF) };
   return cWriteMemory(ADDR_CMD_REG, command, 2);
}

//--------------------------------------------------------------------------
// Compute S-Secret on DS2465 
//
// 'swap' - true if swapping a page into the computation
// 'page' - page number to swap in
// 'region' - (1) first 1/2 page, (2) second 1/2 page, (3) entire page 
//
// Returns: true write successful
//          false failure to complete read
//
OneWireMaster::CmdResult DS2465::computeSlaveSecret(bool swap, unsigned int pageNum, PageRegion region)
{
   std::uint8_t command[2] = { CMD_CSS, (swap ? (0xC8 | (pageNum << 4) | region) : 0xBF) };
   return writeMemory(ADDR_CMD_REG, command, 2);
}




ISha256MacCoprocessor::CmdResult DS2465::setMasterSecret(const Secret & secret)
{
  OneWireMaster::CmdResult result;
  result = writeMemory(ADDR_SPAD, secret, secret.length);
  if (result == OneWireMaster::Success)
    result = copyScratchpad(1, 0, 1, 0);
  if (result == OneWireMaster::Success)
    wait_ms(8 * eepromWriteDelayMs);
  return (result == OneWireMaster::Success ? ISha256MacCoprocessor::Success : ISha256MacCoprocessor::OperationFailure);
}

ISha256MacCoprocessor::CmdResult DS2465::computeWriteMac(const WriteMacData & writeMacData, Mac & mac) const
{
  OneWireMaster::CmdResult result;
  // Write input data to scratchpad
  result = writeScratchpad(writeMacData, writeMacData.length);
  // Compute MAC
  if (result == OneWireMaster::Success)
    result = computeWriteMac(false, false, 0, 0);
  if (result == OneWireMaster::Success)
  {
    wait_ms(shaComputationDelayMs);
    // Read MAC from register
    result = readMemory(ADDR_MAC_READ, mac, mac.length, true);
  }
  return (result == OneWireMaster::Success ? ISha256MacCoprocessor::Success : ISha256MacCoprocessor::OperationFailure);
}

ISha256MacCoprocessor::CmdResult DS2465::computeAuthMac(const DevicePage & devicePage, const DeviceScratchpad & challenge, const AuthMacData & authMacData, Mac & mac) const
{
  OneWireMaster::CmdResult result;
  int addr = ADDR_SPAD;
  // Write input data to scratchpad
  result = cWriteMemory(addr, devicePage, devicePage.length);
  if (result == OneWireMaster::Success)
  {
    addr += devicePage.length;
    result = cWriteMemory(addr, challenge, challenge.length);
  }
  if (result == OneWireMaster::Success)
  {
    addr += challenge.length;
    result = cWriteMemory(addr, authMacData, authMacData.length);
  }
  // Compute MAC
  if (result == OneWireMaster::Success)
    result = computeAuthMac(false, 0, REGION_FULL_PAGE);
  if (result == OneWireMaster::Success)
  {
    wait_ms(shaComputationDelayMs * 2);
    // Read MAC from register
    result = readMemory(ADDR_MAC_READ, mac, mac.length, true);
  }
  return (result == OneWireMaster::Success ? ISha256MacCoprocessor::Success : ISha256MacCoprocessor::OperationFailure);
}

ISha256MacCoprocessor::CmdResult DS2465::computeSlaveSecret(const DevicePage & devicePage, const DeviceScratchpad & deviceScratchpad, const SlaveSecretData & slaveSecretData)
{
  OneWireMaster::CmdResult result;
  int addr = ADDR_SPAD;
  // Write input data to scratchpad
  result = writeMemory(addr, devicePage, devicePage.length);
  if (result == OneWireMaster::Success)
  {
    addr += devicePage.length;
    result = writeMemory(addr, deviceScratchpad, deviceScratchpad.length);
  }
  if (result == OneWireMaster::Success)
  {
    addr += deviceScratchpad.length;
    result = writeMemory(addr, slaveSecretData, slaveSecretData.length);
  }
  // Compute secret
  if (result == OneWireMaster::Success)
    result = computeSlaveSecret(false, 0, REGION_FULL_PAGE);
  if (result == OneWireMaster::Success)
    wait_ms(shaComputationDelayMs * 2);
  return (result == OneWireMaster::Success ? ISha256MacCoprocessor::Success : ISha256MacCoprocessor::OperationFailure);
}

//--------------------------------------------------------------------------
// Copy Scratchpad on DS2465 to either secret or memory page
//
// 'destSecret' - 1 if destination is secret, 0 if memory page
// 'page' - page number if destSecret=0
// 'notfull' - 0 if only 4 byte segment, 1 if writing to full page, 
// 'seg' - Segment number if full=0.
//
// Returns: true write successful
//          false failure to complete read
//
OneWireMaster::CmdResult DS2465::copyScratchpad(bool destSecret, unsigned int pageNum, bool notFull, unsigned int segmentNum)	
{
  std::uint8_t command[2] = { CMD_CPS, (destSecret ? 0 : (0x80 | (pageNum << 4) | (notFull << 3) | segmentNum)) };
  return writeMemory(ADDR_CMD_REG, command, 2);
}




OneWireMaster::CmdResult DS2465::configureLevel(OWLevel level)
{
  OneWireMaster::CmdResult result;
  if (m_curConfig.cSPU != (level == LEVEL_STRONG))
  {
    m_curConfig.cSPU = (level == LEVEL_STRONG);
    result = writeConfig(m_curConfig, true);
  }
  else
  {
    result = OneWireMaster::Success;
  }
  return result;
}

//--------------------------------------------------------------------------
// Set the 1-Wire Net line level pull-up to normal. The DS2465 does only
// allows enabling strong pull-up on a bit or byte event. Consequently this
// function only allows the MODE_STANDARD argument. To enable strong pull-up
// use OWWriteBytePower or OWReadBitPower.  
//
// 'new_level' - new level defined as
//                MODE_STANDARD     0x00
//
// Returns:  current 1-Wire Net level
//
OneWireMaster::CmdResult DS2465::OWSetLevel(OWLevel new_level)
{
  if (new_level == LEVEL_STRONG)
    return OneWireMaster::OperationFailure;
  
  return configureLevel(new_level);
}

//--------------------------------------------------------------------------
// Set the 1-Wire Net communication speed.
//
// 'new_speed' - new speed defined as
//                MODE_STANDARD   0x00
//                MODE_OVERDRIVE  0x01
//
// Returns:  current 1-Wire Net speed
//
OneWireMaster::CmdResult DS2465::OWSetSpeed(OWSpeed new_speed)
{
  // Requested speed is already set
  if (m_curConfig.c1WS == (new_speed == SPEED_OVERDRIVE))
    return OneWireMaster::Success;
       
  // set the speed
  m_curConfig.c1WS = (new_speed == SPEED_OVERDRIVE);

  // write the new config
  return writeConfig(m_curConfig, true);
}

//--------------------------------------------------------------------------
// Use the DS2465 help command '1-Wire triplet' to perform one bit of a 1-Wire
// search. This command does two read bits and one write bit. The write bit
// is either the default direction (all device have same bit) or in case of 
// a discripancy, the 'search_direction' parameter is used. 
//
// Returns � The DS2465 status byte result from the triplet command
//
OneWireMaster::CmdResult DS2465::OWTriplet(SearchDirection & search_direction, std::uint8_t & sbr, std::uint8_t & tsb) 
{
  // 1-Wire Triplet (Case B)
  //   S AD,0 [A] 1WT [A] SS [A] Sr AD,1 [A] [Status] A [Status] A\ P
  //                                         \--------/        
  //                           Repeat until 1WB bit has changed to 0
  //  [] indicates from slave
  //  SS indicates byte containing search direction bit value in msbit
  
  OneWireMaster::CmdResult result;
  std::uint8_t command[2] = { CMD_1WT, ((search_direction == DIRECTION_WRITE_ONE) ? 0x80 : 0x00) };
  result = writeMemory(ADDR_CMD_REG, command, 2);
  if (result == OneWireMaster::Success)
  {
    std::uint8_t status;
    result = pollBusy(&status);
    if (result == OneWireMaster::Success)
    {
      // check bit results in status byte
      sbr = ((status & STATUS_SBR) == STATUS_SBR);
      tsb = ((status & STATUS_TSB) == STATUS_TSB);
      search_direction = ((status & STATUS_DIR) == STATUS_DIR) ? DIRECTION_WRITE_ONE : DIRECTION_WRITE_ZERO;
    }
  }
  return result;
}

//--------------------------------------------------------------------------
// The 'OWReadBlock' receives a block of data from the
// 1-Wire Net. The destination is the mac buffer (rx_mac=1) or 
// the scratchpad (rx_mac=0). The result is buffer is returned. 
//
// 'rx_buf'   - pointer to a block to receive bytes
//              of length 'rx_len' from 1-Wire Net
// 'rx_len' - length in bytes to read. Only valid numbers are 8,16,20,32;
//
OneWireMaster::CmdResult DS2465::OWReadBlock(std::uint8_t *rx_buf, std::uint8_t rx_len)	
{
  // 1-Wire Receive Block (Case A)
  //   S AD,0 [A] ADDR_CMD_REG [A] 1WRF [A] PR [A] P
  //  [] indicates from slave
  //  PR indicates byte containing parameter

  OneWireMaster::CmdResult result;
  std::uint8_t command[2] = { CMD_1WRF, rx_len };
  
  result = writeMemory(ADDR_CMD_REG, command, 2);
  if (result == OneWireMaster::Success)
    result = pollBusy();
  if (result == OneWireMaster::Success) 
    result = readMemory(ADDR_SPAD, rx_buf, rx_len, false);

  return result;
}




OneWireMaster::CmdResult DS2465::OWWriteBlock(const std::uint8_t *tran_buf, std::uint8_t tran_len)
{
  return OWWriteBlock(false, tran_buf, tran_len);
}

//--------------------------------------------------------------------------
// The 'OWWriteBlock' transfers a block of data to the
// 1-Wire Net. The mac buffer can be sent (tx_mac=1) or a
// portion of the scratchpad can be sent. 
//
// 'tx_mac'   - flag to indicate if the MAC buffer is to be sent (1) or
//              the data provided in teh tran_buf is to be sent (0)
// 'tran_buf' - pointer to a block of bytes
//              of length 'tran_len' that will be sent
//              to the 1-Wire Net
// 'tran_len' - length in bytes to transfer. Only valid numbers are 8,16,20,32;
//
OneWireMaster::CmdResult DS2465::OWWriteBlock(bool tx_mac, const std::uint8_t *tran_buf, std::uint8_t tran_len)
{
  OneWireMaster::CmdResult result;
  std::uint8_t command[2] = { CMD_1WTB, (tx_mac ? 0xFF : tran_len) };

  if (!tx_mac)
  {
    // prefill scratchpad with required data
    result = writeMemory(ADDR_SPAD, tran_buf, tran_len);
    if (result != OneWireMaster::Success)
      return result;
  }

  // 1-Wire Transmit Block (Case A)
  //   S AD,0 [A] ADDR_CMD_REG [A] 1WTB [A] PR [A] P
  //  [] indicates from slave
  //  PR indicates byte containing parameter
  
  result = writeMemory(ADDR_CMD_REG, command, 2);
  
  if (result == OneWireMaster::Success)
    result = pollBusy();

  return result;
}

//--------------------------------------------------------------------------
// Send 8 bits of read communication to the 1-Wire Net and return the
// result 8 bits read from the 1-Wire Net.
//
// Returns:  8 bits read from 1-Wire Net
//
OneWireMaster::CmdResult DS2465::OWReadByte(std::uint8_t & recvbyte, OWLevel after_level)	
{
  OneWireMaster::CmdResult result;
  std::uint8_t buf;

  // 1-Wire Read Bytes (Case C)
  //   S AD,0 [A] ADDR_CMD_REG [A] 1WRB [A] Sr AD,1 [A] [Status] A [Status] A 
  //                                                  \--------/        
  //                     Repeat until 1WB bit has changed to 0
  //   Sr AD,0 [A] SRP [A] E1 [A] Sr AD,1 [A] DD A\ P
  //                                  
  //  [] indicates from slave
  //  DD data read
  
  result = configureLevel(after_level);
  if (result != OneWireMaster::Success)
    return result;
   
  buf = CMD_1WRB;
  result = writeMemory(ADDR_CMD_REG, &buf, 1);

  if (result == OneWireMaster::Success)
    result = pollBusy();

  if (result == OneWireMaster::Success)
    result = readMemory(ADDR_DATA_REG, &buf, 1);
  
  if (result == OneWireMaster::Success)
    recvbyte = buf;
   
  return result;
}

//--------------------------------------------------------------------------
// Send 8 bits of communication to the 1-Wire Net and verify that the
// 8 bits read from the 1-Wire Net is the same (write operation).
// The parameter 'sendbyte' least significant 8 bits are used.
//
// 'sendbyte' - 8 bits to send (least significant byte)
//
// Returns:  true: bytes written and echo was the same
//           false: echo was not the same
//
OneWireMaster::CmdResult DS2465::OWWriteByte(std::uint8_t sendbyte, OWLevel after_level)	
{    
  // 1-Wire Write Byte (Case B)
  //   S AD,0 [A] ADDR_CMD_REG [A] 1WWB [A] DD [A] Sr AD,1 [A] [Status] A [Status] A\ P
  //                                                           \--------/        
  //                             Repeat until 1WB bit has changed to 0
  //  [] indicates from slave
  //  DD data to write
  
  OneWireMaster::CmdResult result;
  
  result = configureLevel(after_level);
  if (result != OneWireMaster::Success)
    return result;
  
  std::uint8_t command[2] = { CMD_1WWB, sendbyte };
  
  result = writeMemory(ADDR_CMD_REG, command, 2);
  if (result == OneWireMaster::Success)
    result = pollBusy();

  return result;
}

//--------------------------------------------------------------------------
// Send 1 bit of communication to the 1-Wire Net and return the
// result 1 bit read from the 1-Wire Net.  The parameter 'sendbit'
// least significant bit is used and the least significant bit
// of the result is the return bit.
//
// 'sendbit' - the least significant bit is the bit to send
//
// Returns: 0:   0 bit read from sendbit
//          1:   1 bit read from sendbit
//
OneWireMaster::CmdResult DS2465::OWTouchBit(std::uint8_t & sendrecvbit, OWLevel after_level)	
{
  // 1-Wire bit (Case B)
  //   S AD,0 [A] ADDR_CMD_REG [A] 1WSB [A] BB [A] Sr AD,1 [A] [Status] A [Status] A\ P
  //                                                          \--------/        
  //                           Repeat until 1WB bit has changed to 0
  //  [] indicates from slave
  //  BB indicates byte containing bit value in msbit

  OneWireMaster::CmdResult result;
  
  result = configureLevel(after_level);
  if (result != OneWireMaster::Success)
    return result;
  
  std::uint8_t command[2] = { CMD_1WSB, (sendrecvbit ? 0x80 : 0x00) };
  std::uint8_t status;
  
  result = writeMemory(ADDR_CMD_REG, command, 2);
  
  if (result == OneWireMaster::Success)
    result = pollBusy(&status);
 
  if (result == OneWireMaster::Success)
    sendrecvbit = (status & STATUS_SBR);
  
  return result;
}

//--------------------------------------------------------------------------
// Write to Scratchpad (SRAM) memory on the DS2465
//
// 'addr' - address to start writing (must be in SRAM)
// 'buf' - buffer of data to write
// 'len' - length to write
//
// Returns: true write successful
//          false failure to complete write
//
OneWireMaster::CmdResult DS2465::cWriteMemory(std::uint8_t addr, const std::uint8_t * buf, std::size_t bufLen) const
{
  int i;

  // Write SRAM (Case A)
  //   S AD,0 [A] VSA [A] DD [A]  P
  //                      \-----/
  //                        Repeat for each data byte
  //  [] indicates from slave
  //  VSA valid SRAM memory address
  //  DD memory data to write
  
  m_I2C_interface.start();
  if (m_I2C_interface.write((m_I2C_address | I2C_WRITE)) != I2C_WRITE_OK)
  {
     m_I2C_interface.stop();
     return OneWireMaster::CommunicationWriteError;
  }
  if (m_I2C_interface.write(addr) != I2C_WRITE_OK)
  {
     m_I2C_interface.stop();
     return OneWireMaster::CommunicationWriteError;
  }
  // loop to write each byte
  for (i = 0; i < bufLen; i++)
  {
     if (m_I2C_interface.write(buf[i]) != I2C_WRITE_OK)
     {
        m_I2C_interface.stop();
        return OneWireMaster::CommunicationWriteError;
     }
  }
  m_I2C_interface.stop();
   
   return OneWireMaster::Success;
}

//--------------------------------------------------------------------------
// Read memory from the DS2465
//
// 'addr' - address to start reading
// 'buf' - buffer to hold memory read
// 'len' - length to read
// 'skipSetPointer' - flag to indicate to skip setting address pointer
//
// Returns: true read successful
//          false failure to complete read
//
OneWireMaster::CmdResult DS2465::readMemory(std::uint8_t addr, std::uint8_t * buf, std::size_t bufLen, bool skipSetPointer) const
{
   int i;

   // Read (Case A)
   //   S AD,0 [A] MA [A] Sr AD,1 [A] [DD] A [DD] A\ P
   //                                 \-----/
   //                                   Repeat for each data byte, NAK last byte
   //  [] indicates from slave
   //  MA memory address
   //  DD memory data read

      m_I2C_interface.start();
      if (!skipSetPointer)
      {
         if (m_I2C_interface.write((m_I2C_address | I2C_WRITE)) != I2C_WRITE_OK)
         {
            m_I2C_interface.stop();
            return OneWireMaster::CommunicationWriteError;
         }
         if (m_I2C_interface.write(addr) != I2C_WRITE_OK)
         {
            m_I2C_interface.stop();
            return OneWireMaster::CommunicationWriteError;
         }
         m_I2C_interface.start();
      }

      if (m_I2C_interface.write((m_I2C_address | I2C_READ)) != I2C_WRITE_OK)
      {
         m_I2C_interface.stop();
         return OneWireMaster::CommunicationWriteError;
      }
      // loop to read each byte, NAK last byte
      for (i = 0; i < bufLen; i++)
      {
         buf[i] = m_I2C_interface.read((i == (bufLen - 1)) ? m_I2C_interface.NoACK : m_I2C_interface.ACK);
      }
      m_I2C_interface.stop();
  
   return OneWireMaster::Success;
}

//--------------------------------------------------------------------------
// Write the configuration register in the DS2465. The configuration 
// options are provided in the lower nibble of the provided config byte. 
// The uppper nibble in bitwise inverted when written to the DS2465.
//  
// Returns:  true: config written and response correct
//           false: response incorrect
//
OneWireMaster::CmdResult DS2465::writeConfig(const Config & config, bool verify)
{
   std::uint8_t configBuf;
   OneWireMaster::CmdResult result;
   
   configBuf = config.writeByte();
   result = writeMemory(ADDR_WCFG_REG, &configBuf, 1);
   if (verify)
   {
     if (result == OneWireMaster::Success)
     {
       result = readMemory(ADDR_WCFG_REG, &configBuf, 1);
     }
     if (result == OneWireMaster::Success)
     {
       if (configBuf != config.readByte())
         result = OneWireMaster::OperationFailure;
     }
   }
   
   return result;
}



DS2465::Config DS2465::currentConfig() const
{
  return m_curConfig;
}




OneWireMaster::CmdResult DS2465::pollBusy(std::uint8_t * pStatus)
{
    const unsigned int pollLimit = 200;
    
    OneWireMaster::CmdResult result;
    std::uint8_t status;
    unsigned int pollCount = 0;
    
   // loop checking 1WB bit for completion of 1-Wire operation 
   // abort if poll limit reached
   
   do
   {
      result = readMemory(ADDR_STATUS_REG, &status, 1, true);
      if (result != OneWireMaster::Success)
        return result;
      if (pStatus != NULL)
          *pStatus = status;
      if (pollCount++ >= pollLimit)
        return OneWireMaster::TimeoutError;
   } while (status & STATUS_1WB);

   return OneWireMaster::Success;
}

//--------------------------------------------------------------------------
// Reset all of the devices on the 1-Wire Net and return the result.
//
// Returns: true(1):  presense pulse(s) detected, device(s) reset
//          false(0): no presense pulses detected
//
OneWireMaster::CmdResult DS2465::OWReset(void)
{     
  // 1-Wire reset (Case B)
  //   S AD,0 [A] ADDR_CMD_REG  [A] 1WRS [A] Sr AD,1 [A] [Status] A [Status] A\ P
  //                                                  \--------/        
  //                       Repeat until 1WB bit has changed to 0
  //  [] indicates from slave
   
  OneWireMaster::CmdResult result;
  std::uint8_t buf;
    
  buf = CMD_1WRS;
  result = writeMemory(ADDR_CMD_REG, &buf, 1);

  if (result == OneWireMaster::Success)
    result = pollBusy(&buf);
  
  if (result == OneWireMaster::Success)
  {       
    // check for presence detect
    if ((buf & STATUS_PPD) != STATUS_PPD)
      result = OneWireMaster::OperationFailure;
  }

  return result;
}

OneWireMaster::CmdResult DS2465::reset(void)
{  
  // Device Reset
  //   S AD,0 [A] ADDR_CMD_REG [A] 1WMR [A] Sr AD,1 [A] [SS] A\ P
  //  [] indicates from slave
  //  SS status byte to read to verify state
  
  OneWireMaster::CmdResult result;
  std::uint8_t buf;
  
  buf = CMD_1WMR;
  result = writeMemory(ADDR_CMD_REG, &buf, 1);
  
  if (result == OneWireMaster::Success)
    result = readMemory(ADDR_STATUS_REG, &buf, 1, true);

  if (result == OneWireMaster::Success)
  {
    if ((buf & 0xF7) != 0x10)
      result = OneWireMaster::OperationFailure;
  }
   
  if (result == OneWireMaster::Success)
    OWReset(); // do a command to get 1-Wire master reset out of holding state

  return result;
}

OneWireMaster::CmdResult DS2465::detect()
{
  OneWireMaster::CmdResult result;
  
  // reset DS2465 
  result = reset();
  if (result != OneWireMaster::Success)
    return result;
  
  // default configuration
   m_curConfig.reset();

   // write the default configuration setup
   result = writeConfig(m_curConfig, true);
   return result;
}