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785 lines
24 KiB
785 lines
24 KiB
// $Header: G:/SwDev/WDM/Video/bt848/rcs/I2c.cpp 1.6 1998/05/08 18:18:52 tomz Exp $
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//===========================================================================
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// I2C DATA/CONTROL REGISTER API
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//===========================================================================
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#include "bti2c.h"
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//**************************************************************************
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// DEFINES
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//**************************************************************************
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#define I2C_WRITE 0 // write operation
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#define I2C_READ 1 // read operation
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#define PCI_FREQ 33000000L // frequency for PCI in hz
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#define I2CDIV_MAX 15 // I2C maximum divider
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#define TIMEOUT 500 // timeout value (500ms) to wait for an I2C operation
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// passing 3 values to I2C takes ~450ms
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#ifdef HAUPPAUGEI2CPROVIDER
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extern "C" ULONG GetTickCount( void );
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#endif
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// Let me know at compile time what i2c setup I'm building
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#if SHOW_BUILD_MSGS
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#ifdef HAUPPAUGEI2CPROVIDER
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#pragma message("*** using 'Hauppauge' i2c code")
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#else
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#pragma message("*** not using 'Hauppauge' i2c code")
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#endif
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#ifdef HARDWAREI2C
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#pragma message("*** using hardware i2c code")
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#else
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#pragma message("*** not using hardware i2c code")
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#endif
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#endif
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//===========================================================================
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// Bt848 I2C Class Implementation
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//===========================================================================
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/////////////////////////////////////////////////////////////////////////////
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// Constructor
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/////////////////////////////////////////////////////////////////////////////
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I2C::I2C( void ) :
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// construct I2C register and register fields
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decRegINT_STAT ( 0x100, RW ), // Interrupt Status register
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decFieldI2CDONE( decRegINT_STAT, 8, 1, RR ),
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decFieldRACK( decRegINT_STAT, 25, 1, RO ),
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decRegI2C ( 0x110, RW ), // I2C Data/Control register
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decFieldI2CDB0( decRegI2C, 24, 8, RW ),
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decFieldI2CDB1( decRegI2C, 16, 8, RW ),
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decFieldI2CDB2( decRegI2C, 8, 8, RW ),
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decFieldI2CDIV( decRegI2C, 4, 4, RW),
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decFieldSYNC( decRegI2C, 3, 1, RW),
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decFieldW3B( decRegI2C, 2, 1, RW),
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decFieldSCL( decRegI2C, 1, 1, RW),
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decFieldSDA( decRegI2C, 0, 1, RW)
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{
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initOK = false;
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cycle = 0L;
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errNum = I2CERR_OK;
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mode = I2CMode_None;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Destructor
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/////////////////////////////////////////////////////////////////////////////
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I2C::~I2C()
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{
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: bool I2C::IsInitOK( void )
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// Purpose: Check if I2C is initialized successfully
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// Input: None
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// Output: None
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// Return: true or false
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/////////////////////////////////////////////////////////////////////////////
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bool I2C::IsInitOK( void )
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{
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// initialize I2C register shadow
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I2CResetShadow();
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initOK = true;
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return( initOK );
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}
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#ifdef HARDWAREI2C
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CInitHWMode( long freq )
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// Purpose: Initialize I2C for hardware control of SCL and SDA
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// Input: long freq - frequency (hz) to run SCL at
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// Output: None
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// Return: None
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CInitHWMode( long freq )
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{
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// initialization was successful?
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if ( initOK != true )
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{
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errNum = I2CERR_INIT;
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return Fail;
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}
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// initialize I2C register shadow
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I2CResetShadow();
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decFieldSCL = sh.i2cShadow.scl = 1; // must be 1 for hardware mode
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decFieldSDA = sh.i2cShadow.sda = 1; // must be 1 for hardware mode
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I2CSetFreq( freq ); // set frequency for hardware control
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// I2C is running hardware mode
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mode = I2CMode_HW;
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return Success;
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}
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#endif
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/////////////////////////////////////////////////////////////////////////////
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// Method: void I2C::I2CSetFreq( long freq )
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// Purpose: Set frequency for SCL
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// Input: long freq - frequency (hz) to run SCL at. (137.5khz to 2.0625Mhz)
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// PCI frequency 33Mhz: SCL = (412.50Khz to 33.81Khz)
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// 25Mhz: SCL = (312.50Khz to 25.61Khz)
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// Output: None
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// Return: None
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/////////////////////////////////////////////////////////////////////////////
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void I2C::I2CSetFreq( long freq )
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{
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unsigned int i2cdiv;
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// avoid division errors
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if( freq > 1 )
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i2cdiv = (unsigned int) (PCI_FREQ / (64 * freq));
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else
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i2cdiv = 0;
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if( i2cdiv > I2CDIV_MAX )
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i2cdiv = I2CDIV_MAX;
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decFieldI2CDIV = sh.i2cShadow.div = i2cdiv;
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}
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#ifdef HARDWAREI2C
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/////////////////////////////////////////////////////////////////////////////
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// Method: int I2C::I2CReadDiv( void )
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// Purpose: Obtain value of programmable divider
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// Input: None
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// Output: None
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// Return: Value of programmable divider
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/////////////////////////////////////////////////////////////////////////////
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int I2C::I2CReadDiv( void )
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{
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return decFieldI2CDIV;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CHWRead( BYTE address, BYTE *value )
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// Purpose: Perform a hardware read from the I2C
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// Input: int address - address to be read from
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// Output: int *value - retrieved value
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// Return: Success or Fail
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CHWRead( BYTE address, BYTE *value )
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{
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// check if correct mode is selected
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if ( mode != I2CMode_HW )
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{
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errNum = I2CERR_MODE;
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return Fail;
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}
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shadow::_i2c_reg i2cTemp = sh.i2cShadow; // obtain previous settings that didn't change
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// see above for reasons of doing all these.
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i2cTemp.addr_rw = address | I2C_READ;
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i2cTemp.byte1 = 0;
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i2cTemp.byte2 = 0;
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i2cTemp.w3b = 0;
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decRegI2C = *(DWORD *)&i2cTemp;
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if ( I2CHWWaitUntilDone( TIMEOUT ) == Fail )
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{
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errNum = I2CERR_TIMEOUT;
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return Fail;
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}
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*value = (BYTE) decFieldI2CDB2; // returned value is in 3rd byte
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if ( I2CHWReceivedACK() == true )
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return Success;
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else
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{
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errNum = I2CERR_NOACK;
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return Fail;
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}
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CHWWrite2( BYTE address, BYTE value1 )
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// Purpose: Perform a hardware write of two bytes to the I2C
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// Input: int address - address to be written to
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// int value1 - value of 2nd byte to be written
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// Output: None
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// Return: Success or Fail
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CHWWrite2( BYTE address, BYTE value1 )
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{
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// check if correct mode is selected
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if ( mode != I2CMode_HW )
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{
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errNum = I2CERR_MODE;
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return Fail;
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}
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shadow::_i2c_reg i2cTemp = sh.i2cShadow; // obtain previous settings that didn't change
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// see above for reasons of doing all these.
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i2cTemp.addr_rw = address | I2C_WRITE;
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i2cTemp.byte1 = value1;
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i2cTemp.byte2 = 0;
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i2cTemp.w3b = 0;
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decRegI2C = *(DWORD *)&i2cTemp;
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if ( I2CHWWaitUntilDone( TIMEOUT ) == Fail )
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{
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errNum = I2CERR_TIMEOUT;
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return Fail;
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}
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if ( I2CHWReceivedACK() == true )
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return Success;
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else
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{
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errNum = I2CERR_NOACK;
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return Fail;
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}
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CHWWrite3( BYTE address, BYTE value1, BYTE value2 )
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// Purpose: Perform a hardware write of three bytes to the I2C
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// Input: int address - address to be written to
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// int value1 - value of 2nd byte to be written
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// int value2 - value of 3rd byte to be written
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// Output: None
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// Return: Success or Fail
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CHWWrite3( BYTE address, BYTE value1, BYTE value2 )
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{
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// check if correct mode is selected
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if ( mode != I2CMode_HW )
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{
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errNum = I2CERR_MODE;
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return Fail;
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}
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shadow::_i2c_reg i2cTemp = sh.i2cShadow; // obtain previous settings that didn't change
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// see above for reasons of doing all these.
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i2cTemp.addr_rw = address | I2C_WRITE;
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i2cTemp.byte1 = value1;
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i2cTemp.byte2 = value2;
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i2cTemp.w3b = 1;
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decRegI2C = *(DWORD *)&i2cTemp;
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if ( I2CHWWaitUntilDone( TIMEOUT ) == Fail )
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{
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errNum = I2CERR_TIMEOUT;
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return Fail;
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}
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if ( I2CHWReceivedACK() == true )
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return Success;
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else
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{
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errNum = I2CERR_NOACK;
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return Fail;
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}
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: int I2C::I2CReadSync( void )
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// Purpose: Read I2C sync value
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// Input: None
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// Output: None
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// Return: Sync value
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/////////////////////////////////////////////////////////////////////////////
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int I2C::I2CReadSync( void )
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{
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return decFieldSYNC;
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}
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#endif
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/////////////////////////////////////////////////////////////////////////////
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// Method: int I2C::I2CGetLastError( void )
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// Purpose: Obtain last I2C error number
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// Input: None
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// Output: None
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// Return: Last I2C error number
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/////////////////////////////////////////////////////////////////////////////
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int I2C::I2CGetLastError( void )
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{
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return errNum;
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}
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//============================================================================
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// Following functions are used internally
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//============================================================================
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/////////////////////////////////////////////////////////////////////////////
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// Method: void I2C::I2CResetShadow( void )
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// Purpose: Reset register shadow
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// Input: int maxWait - maximum waiting time in milliseconds
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// Output: None
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// Return: Success if done; Fail if timeout
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/////////////////////////////////////////////////////////////////////////////
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void I2C::I2CResetShadow( void )
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{
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// initialize I2C register shadow
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sh.Initer = 0;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CHWWaitUntilDone( int maxWait )
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// Purpose: Wait for hardware I2C to finish
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// Input: int maxWait - maximum waiting time in milliseconds
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// Output: None
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// Return: Success if done; Fail if timeout
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CHWWaitUntilDone( int maxWait )
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{
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// DWORD startTime = GetTickCount();
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// loop until either I2CDONE is set or timeout
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while (1)
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{
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if ( I2CHWIsDone() == true )
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return Success;
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#if 0
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// timeout?
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if ( GetTickCount() - startTime > (DWORD)maxWait )
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{
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errNum = I2CERR_TIMEOUT;
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return Fail;
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}
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#endif
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}
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: bool I2C::I2CHWIsDone( void )
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// Purpose: Determine if I2C has finished a read or write operation by
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// checking the I2CDONE bit in the interrupt status register
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// Input: None
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// Output: None
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// Return: true if done; else false
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/////////////////////////////////////////////////////////////////////////////
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bool I2C::I2CHWIsDone( void )
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{
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if ( decFieldI2CDONE != 0 )
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{
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// Need to clear the bit when it is set; don't want to alter any other bits
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// Writing a 1 to the bit clears it.
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decFieldI2CDONE = 1;
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return true;
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}
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else
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return false;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: bool I2C::I2CHWReceivedACK( void )
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// Purpose: Determine if ACK is receieved
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// Input: None
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// Output: None
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// Return: true if ACK received; else false
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/////////////////////////////////////////////////////////////////////////////
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bool I2C::I2CHWReceivedACK( void )
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{
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return ( ( decFieldRACK != 0 ) ? true : false );
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}
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#ifdef HAUPPAUGEI2CPROVIDER
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CInitSWMode( long freq )
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// Purpose: Initialize I2C for software control of SCL and SDA
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// Input: long freq - frequency (hz) to run SCL at
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// Output: None
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// Return: None
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// Note: After calling I2CIsInitOK(), application should call this
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// function and check for return value is Success before starting
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// software communication.
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CInitSWMode( long freq )
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{
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// initialization was successful?
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if ( initOK != true )
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{
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errNum = I2CERR_INIT;
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return Fail;
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}
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// initialize I2C register shadow
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I2CResetShadow();
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decFieldSCL = sh.i2cShadow.scl = 1;
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decFieldSDA = sh.i2cShadow.sda = 1;
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I2CSetFreq( 0 ); // set frequency to 0 for software control
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// need to calibrate in order to generate the correct clock cycle
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// the approach is to calculate how many dummy loop we need in order to
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// generate a cycle that is 2 * freq * 1000 Hz
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cycle = 10000L; // use a large number to start
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DWORD elapsed = 0L;
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while ( elapsed < 5 ) // loop until delay is long enough for calculation
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{
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cycle *= 10;
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DWORD start = GetTickCount();
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for ( volatile DWORD i = cycle; i > 0; i-- )
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;
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elapsed = GetTickCount() - start;
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}
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if ( freq > 1 )
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cycle = cycle / elapsed * 1000L / freq / 2;
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// I2C is running software mode
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mode = I2CMode_SW;
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return Success;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CSWStart( void )
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// Purpose: Generate START condition using software control
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// Input: None
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// Output: None
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// Return: Success or Fail
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CSWStart( void )
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{
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// check if correct mode is selected
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if ( mode != I2CMode_SW )
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{
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errNum = I2CERR_MODE;
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return Fail;
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}
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// SendStart - send an I2c start
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// i.e. SDA 1 -> 0 with SCL = 1
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if ( I2CSWSetSDA( LevelHi ) != Success ) { errNum = I2CERR_SDA; return Fail; }
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if ( I2CSWSetSCL( LevelHi ) != Success ) { errNum = I2CERR_SCL; return Fail; }
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if ( I2CSWSetSDA( LevelLow ) != Success ) { errNum = I2CERR_SDA; return Fail; }
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if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
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return Success;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CSWStop( void )
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// Purpose: Generate STOP condition using software control
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// Input: None
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// Output: None
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// Return: Success or Fail
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CSWStop( void )
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{
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// check if correct mode is selected
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if ( mode != I2CMode_SW )
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{
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errNum = I2CERR_MODE;
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return Fail;
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}
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// SendStop - sends an I2C stop, releasing the bus.
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// i.e. SDA 0 -> 1 with SCL = 1
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if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
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if ( I2CSWSetSDA( LevelLow ) != Success ) { errNum = I2CERR_SDA; return Fail; }
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if ( I2CSWSetSCL( LevelHi ) != Success ) { errNum = I2CERR_SCL; return Fail; }
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if ( I2CSWSetSDA( LevelHi ) != Success ) { errNum = I2CERR_SDA; return Fail; }
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return Success;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CSWRead( BYTE * value )
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// Purpose: Read a byte from the slave
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// Input: None
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// Output: BYTE * value - byte read from slave
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// Return: Success or Fail
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/////////////////////////////////////////////////////////////////////////////
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ErrorCode I2C::I2CSWRead( BYTE * value )
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{
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// check if correct mode is selected
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if ( mode != I2CMode_SW )
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{
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errNum = I2CERR_MODE;
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return Fail;
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}
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*value = 0x00;
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// read 8 bits from I2c into Accumulator
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for( BYTE mask = 0x80; mask > 0; mask = (BYTE)( mask >> 1 ) )
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{
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if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
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if ( I2CSWSetSCL( LevelHi ) != Success ) { errNum = I2CERR_SCL; return Fail; }
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if ( I2CSWReadSDA() == TRUE )
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*value = (BYTE)( *value | mask ); // set the bit
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}
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return Success;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Method: ErrorCode I2C::I2CSWWrite( BYTE value )
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// Purpose: Write a byte to the slave
|
|
// Input: BYTE value - byte to be written to slave
|
|
// Output: None
|
|
// Return: Success or Fail
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
ErrorCode I2C::I2CSWWrite( BYTE value )
|
|
{
|
|
// check if correct mode is selected
|
|
if ( mode != I2CMode_SW )
|
|
{
|
|
errNum = I2CERR_MODE;
|
|
return Fail;
|
|
}
|
|
|
|
// generate bit patterns by setting SCL and SDA lines
|
|
for ( BYTE mask = 0x80; mask > 0; mask = (BYTE)(mask >> 1) )
|
|
{
|
|
if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
|
|
// Send one data bit.
|
|
if ( value & mask ) // Put data bit on pin.
|
|
{
|
|
if ( I2CSWSetSDA( LevelHi ) != Success ) { errNum = I2CERR_SDA; return Fail; }
|
|
}
|
|
else
|
|
{
|
|
if ( I2CSWSetSDA( LevelLow ) != Success ) { errNum = I2CERR_SDA; return Fail; }
|
|
}
|
|
|
|
if ( I2CSWSetSCL( LevelHi ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
}
|
|
|
|
return I2CSWWaitForACK();
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Method: ErrorCode I2C::I2CSWSendACK( void )
|
|
// Purpose: Send ACK to slave
|
|
// Input: None
|
|
// Output: None
|
|
// Return: Success or Fail
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
ErrorCode I2C::I2CSWSendACK( void )
|
|
{
|
|
// check if correct mode is selected
|
|
if ( mode != I2CMode_SW )
|
|
{
|
|
errNum = I2CERR_MODE;
|
|
return Fail;
|
|
}
|
|
|
|
// Generate ACK signal
|
|
// i.e. SDA = 0 with SCL = 1
|
|
|
|
if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
if ( I2CSWSetSDA( LevelLow ) != Success ) { errNum = I2CERR_SDA; return Fail; }
|
|
if ( I2CSWSetSCL( LevelHi ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
if ( I2CSWSetSDA( LevelHi ) != Success ) { errNum = I2CERR_SDA; return Fail; }
|
|
return Success;
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Method: ErrorCode I2C::I2CSWSendNACK( void )
|
|
// Purpose: Send NACK to slave
|
|
// Input: None
|
|
// Output: None
|
|
// Return: Success or Fail
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
ErrorCode I2C::I2CSWSendNACK( void )
|
|
{
|
|
// check if correct mode is selected
|
|
if ( mode != I2CMode_SW )
|
|
{
|
|
errNum = I2CERR_MODE;
|
|
return Fail;
|
|
}
|
|
|
|
// Generate NACK signal
|
|
// i.e. SDA = 1 with SCL = 1
|
|
|
|
if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
if ( I2CSWSetSDA( LevelHi ) != Success ) { errNum = I2CERR_SDA; return Fail; }
|
|
if ( I2CSWSetSCL( LevelHi ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
if ( I2CSWSetSDA( LevelLow ) != Success ) { errNum = I2CERR_SDA; return Fail; }
|
|
return Success;
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Method: ErrorCode I2C::I2CSWSetSCL( Level scl )
|
|
// Purpose: Set software SCL value
|
|
// Input: Level scl - Hi releases the SCL output; Low forces the SCL output low
|
|
// Output: None
|
|
// Return: Success or Fail
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
ErrorCode I2C::I2CSWSetSCL( Level scl )
|
|
{
|
|
// check if correct mode is selected
|
|
if ( mode != I2CMode_SW )
|
|
{
|
|
errNum = I2CERR_MODE;
|
|
return Fail;
|
|
}
|
|
|
|
sh.i2cShadow.scl = scl;
|
|
decRegI2C = *(DWORD *)&(sh.i2cShadow);
|
|
|
|
// loop until SCL really changes or timeout
|
|
DWORD maxWait = 500; // 500 mSec
|
|
DWORD startTime = GetTickCount();
|
|
|
|
while (1)
|
|
{
|
|
// has SCL changed yet?
|
|
if ( I2CSWReadSCL() == scl )
|
|
break;
|
|
|
|
// timeout?
|
|
if ( GetTickCount() - startTime > (DWORD)maxWait )
|
|
{
|
|
errNum = I2CERR_TIMEOUT;
|
|
return Fail;
|
|
}
|
|
}
|
|
|
|
I2CSWBitDelay();
|
|
return Success;
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Method: int I2C::I2CSWReadSCL( void )
|
|
// Purpose: Read software SCL value
|
|
// Input: None
|
|
// Output: None
|
|
// Return: SCL value
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
int I2C::I2CSWReadSCL( void )
|
|
{
|
|
return decFieldSCL;
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Method: ErrorCode I2C::I2CSWSetSDA( Level sda )
|
|
// Purpose: Set software SDA value
|
|
// Input: Level sda - Hi releases the SDA output; Low forces the SDA output low
|
|
// Output: None
|
|
// Return: Success or Fail
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
ErrorCode I2C::I2CSWSetSDA( Level sda )
|
|
{
|
|
// check if correct mode is selected
|
|
if ( mode != I2CMode_SW )
|
|
{
|
|
errNum = I2CERR_MODE;
|
|
return Fail;
|
|
}
|
|
|
|
sh.i2cShadow.sda = sda;
|
|
decRegI2C = *(DWORD *)&(sh.i2cShadow);
|
|
|
|
I2CSWBitDelay();
|
|
return Success;
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Method: int I2C::I2CSWReadSDA( void )
|
|
// Purpose: Read software SDA value
|
|
// Input: None
|
|
// Output: None
|
|
// Return: SDA value
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
int I2C::I2CSWReadSDA( void )
|
|
{
|
|
return decFieldSDA;
|
|
}
|
|
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Method: void I2C::I2CSWBitDelay( void )
|
|
// Purpose: Insures minimum high and low clock times on I2C bus.
|
|
// Input: None
|
|
// Output: None
|
|
// Return: None
|
|
// Note: This routine must be tuned for the desired frequency.
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
void I2C::I2CSWBitDelay( void )
|
|
{
|
|
// unsigned int n;
|
|
volatile DWORD i ;
|
|
for ( i = cycle; i > 0; i-- )
|
|
;
|
|
}
|
|
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
// Method: ErrorCode I2C::I2CSWWaitForACK( void )
|
|
// Purpose: Determine if ACK is receieved in software mode
|
|
// Input: None
|
|
// Output: None
|
|
// Return: Success if ACK received; Fail if timeout
|
|
/////////////////////////////////////////////////////////////////////////////
|
|
ErrorCode I2C::I2CSWWaitForACK( void )
|
|
{
|
|
if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
if ( I2CSWSetSDA( LevelHi ) != Success ) { errNum = I2CERR_SDA; return Fail; }
|
|
|
|
// loop until either ACK or timeout
|
|
DWORD maxWait = 500; // 500 mSec
|
|
DWORD startTime = GetTickCount();
|
|
|
|
while (1)
|
|
{
|
|
// SDA pin == 0 means the slave ACK'd
|
|
if ( I2CSWReadSDA() == 0 )
|
|
{
|
|
if ( I2CSWSetSCL( LevelHi ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
if ( I2CSWSetSCL( LevelLow ) != Success ) { errNum = I2CERR_SCL; return Fail; }
|
|
return Success;
|
|
}
|
|
|
|
// timeout?
|
|
if ( GetTickCount() - startTime > (DWORD)maxWait )
|
|
{
|
|
if ( I2CSWStop() != Success ) return Fail;
|
|
errNum = I2CERR_TIMEOUT;
|
|
return Fail;
|
|
}
|
|
} // while
|
|
}
|
|
|
|
|
|
//
|
|
// GetSystemTime in 100 nS units
|
|
//
|
|
|
|
ULONGLONG GetSystemTime()
|
|
{
|
|
ULONGLONG ticks;
|
|
ULONGLONG rate;
|
|
|
|
ticks = (ULONGLONG)KeQueryPerformanceCounter((PLARGE_INTEGER)&rate).QuadPart;
|
|
|
|
//
|
|
// convert from ticks to 100ns clock
|
|
//
|
|
|
|
ticks = (ticks & 0xFFFFFFFF00000000) / rate * 10000000 +
|
|
(ticks & 0xFFFFFFFF) * 10000000 / rate;
|
|
|
|
return(ticks);
|
|
|
|
}
|
|
|
|
extern "C" ULONG GetTickCount( void )
|
|
{
|
|
return (ULONG)( GetSystemTime() / 10000 );
|
|
}
|
|
|
|
#endif
|