bus.c

采用台湾MRT晶捷公司的MRT4方案的液晶电视的程序

/************************************************
*                                               *
* BUS.C:  BUS control routines.                 *
*                                               *
*************************************************/
#include <reg51.h>
#include <intrins.h>
#include "mascot.h"
#include "OSD.h"
#include "global.h"



#define USE_ASM		1

/*******************************************************************
* Send SCL pin high and wait for any clock stretching peripherals  *
********************************************************************/
#define SCLHigh() 	{ SCLPin  = 1; while(!SCLPin);  }
#define SCLHigh2() 	{ SCLPin2 = 1; while(!SCLPin2); }



/********************************************************
* Grasp the I2C bus, send slave address and command     *
*********************************************************/
void GoI2CMaster(unsigned char adr)
{

	BusBusy = 1;

	if (!SCLPin) SCLHigh();

    NoAck = 0; 
    BusFault = 0;

    if (SCLPin & SDAPin) {
        SDAPin = 0; 
        _nop_();
        SCLPin = 0; 
        _nop_(); 
        SendI2CByte(adr);
    } else
        BusFault = 1;
}




/*********************************************
* Send one byte of data to an I2C device     *
**********************************************/
void SendI2CByte(unsigned char val)
{

#if USE_ASM

	ACC = val;
#pragma asm	

   	MOV     R7,#8
   	
SendByte1:   	
   	RLC		A
   	MOV		SDAPin,C
	NOP
   	SETB	SCLPin
   	JNB		SCLPin,$
	NOP
   	CLR		SCLPin
   	DJNZ 	R7,SendByte1	

	SETB	SDAPin
	NOP
	SETB	SCLPin
	JNB		SCLPin,$
	JNB		SDAPin,SendByte2
	SETB	NoAck
	
SendByte2:	
	CLR		SCLPin
	
#pragma endasm	

#else
	unsigned char bmsk = 0x80;

    while (bmsk) {
        SDAPin = (val & bmsk) ? 0x01 : 0x00;
        SCLHigh(); 
        bmsk >>= 1;
        SCLPin = 0; 
    }


    SDAPin = 1;
    SCLHigh();
    
    if (SDAPin) NoAck = 1;
    
    SCLPin = 0; 

#endif

}         



/*********************************************
* Receive byte of data from an I2C device    *
**********************************************/
unsigned char RcvI2CByte(unsigned char cnt)
{
#if USE_ASM
	
	B = cnt;
#pragma asm	

   	MOV     R7,#8
   	
RcvByte1:
    SETB    SCLPin
    JNB		SCLPin,$
    MOV     C,SDAPin
    RLC     A
    CLR     SCLPin
    DJNZ    R7,RcvByte1

	PUSH	ACC
	MOV		A,B
    CJNE    A,#1,RcvByte2
    SETB    SDAPin
    SJMP    RcvByte3	
    
RcvByte2:
    CLR     SDAPin
	NOP
RcvByte3:
    SETB    SCLPin
    JNB		SCLPin,$
	NOP
 	CLR     SCLPin
	NOP
	SETB    SDAPin
	POP     ACC
	
#pragma	endasm

	return ACC;

#else
                
    unsigned char bval = 0, b;

    for(b=0; b < 8; b++) {
        SCLHigh(); 
        bval <<= 1;
        bval |= SDAPin;
        SCLPin = 0;	
	}

    SDAPin = (cnt==1) ? 1 : 0;
    SCLHigh();
    SCLPin = 0;
    SDAPin = 1;         //Clear acknowledge bit.
    return bval;
#endif    
}

/*************************************
* Send I2C STOP, release bus         *
**************************************/
void SendI2CStop(void)
{
    SDAPin = 0; 
    _nop_();  
    SCLHigh(); 
    _nop_();  
    SDAPin = 1; 
	_nop_();
    BusBusy = 0;
}



#if USE_I2C_2

/********************************************************
* Grasp the I2C bus, send slave address and command     *
*********************************************************/
void GoI2CMaster2(unsigned char adr)
{

	BusBusy = 1;

    if (!SCLPin2) SCLHigh2();

    NoAck  = 0; 
    BusFault = 0;

    if(SCLPin2 & SDAPin2) {
        SDAPin2 = 0; 
        _nop_();  
        SCLPin2 = 0; 
        _nop_();  
        SendI2CByte2(adr);
    } else
        BusFault = 1;
}

/*********************************************
* Send one byte of data to an I2C device     *
**********************************************/
void SendI2CByte2(unsigned char val)
{
#if USE_ASM

	ACC = val;
#pragma asm	

   	MOV     R7,#8
   	
SendByte1:   	
   	RLC		A
   	MOV		SDAPin2,C
   	SETB	SCLPin2
   	JNB		SCLPin2,$
   	CLR		SCLPin2
   	DJNZ 	R7,SendByte1	

	SETB	SDAPin2
	SETB	SCLPin2
	JNB		SCLPin2,$
	JNB		SDAPin2,SendByte2
	SETB	NoAck
	
SendByte2:	
	CLR		SCLPin2
	
#pragma endasm	

#else

	unsigned char bmsk = 0x80;

    while (bmsk) {
        SDAPin2 = (val & bmsk) ? 0x01 : 0x00;
        SCLHigh2();
        bmsk >>= 1;
        SCLPin2 = 0; 
    }

    SDAPin2 = 1;
    SCLHigh2(); 

    if (SDAPin2) NoAck = 1;

    SCLPin2 = 0; 

#endif
}         

/*********************************************
* Receive byte of data from an I2C device    *
**********************************************/
unsigned char RcvI2CByte2(unsigned char cnt)
{

#if USE_ASM
	
	B = cnt;
#pragma asm	

   	MOV     R7,#8
   	
RcvByte1:
    SETB    SCLPin2
    JNB		SCLPin2,$
    MOV     C,SDAPin2
    RLC     A
    CLR     SCLPin2
    DJNZ    R7,RcvByte1

	PUSH	ACC
	MOV		A,B
    CJNE    A,#1,RcvByte2
    SETB    SDAPin2
    SJMP    RcvByte3	
    
RcvByte2:
    CLR     SDAPin2
RcvByte3:
    SETB    SCLPin2
    JNB		SCLPin2,$
 	CLR     SCLPin2
	SETB    SDAPin2
	POP     ACC
	
#pragma	endasm

	return ACC;

#else

    unsigned char bval = 0, b;

    for(b=0; b < 8; b++) {
        SCLHigh2(); 
        bval <<= 1;
        bval |= SDAPin2;
        SCLPin2 = 0;	
	}

    SDAPin2 = (cnt==1) ? 1 : 0;
    SCLHigh2();
    SCLPin2 = 0;
    SDAPin2 = 1;         //Clear acknowledge bit.
    return bval;    

#endif    
}

/*************************************
* Send I2C STOP, release bus         *
**************************************/
void SendI2CStop2(void)
{
    SDAPin2 = 0; 
    _nop_();  
    SCLHigh2(); 
    _nop_();  
    SDAPin2 = 1; 
	_nop_();
    BusBusy = 0;
}

#endif //USE_I2C_2