chap14.c

摩托罗拉Mc6811利程

// Chapter 14 6811 C programs
// Jonathan W. Valvano
// This software accompanies the book,
// Embedded Microcomputer Systems: Real Time Interfacing
// published by Brooks Cole, 1999

 // Program 14.1. AART code to receive from an input-only full-duplex AART.
// AART full duplex Input only, returns ID:S as 16-bit
unsigned int GetAART(unsigned char addr){ // addr specifies which AART
	unsigned char ID,S;     // inputs from AART
	OutCh(addr|0x80);       // activate AART
	ID=InCh();              // read ID
	S=InCh();               // read status
	return((ID<<8)+S);}     // return ID:S as 16-bit unsigned int

//  Program 14.2. AART code to receive from an input-only half-duplex AART.
// AART half duplex Input only, returns ID:S as 16-bit
unsigned int GetAART(unsigned char addr){ // addr specifies which AART
	unsigned char ID,S;     // inputs from AART
	OutCh(addr|0x80);       // activate AART
	InCh();                 // read echo of previous addr output
	ID=InCh();              // read ID
	S=InCh();               // read status
	return((ID<<8)+S);}     // return ID:S as 16-bit unsigned int

//  Program 14.3. AART code to transmit to an output-only half-duplex AART.
// AART full duplex output only
void PutAART(unsigned char addr,data){ // addr specifies which AART
	OutCh(addr|0x80);       // activate AART
	OutCh(data&0x7F);       // send data
	OutCh(addr|0x80);}      // deactivate AART

//  Program 14.4. AART code to transmit to an output-only half-duplex AART.
// AART half duplex output only
void PutAART(unsigned char addr,data){ // addr specifies which AART
	OutCh(addr|0x80);       // activate AART
	InCh();                 // read echo of addr output
	OutCh(data&0x7F);       // send data
	InCh();                 // read echo of data output
	OutCh(addr|0x80);       // deactivate AART
	InCh();}                // read echo of previous output

//  Program 14.5. AART code to transmit then receive.
// AART full duplex Output then Input, returns ID:S as 16-bit
unsigned int PutGetAART(unsigned char addr,data){ // addr specifies which AART
	unsigned char ID,S;     // inputs from AART
	OutCh(addr|0x80);       // activate AART
	OutCh(data&0x7F);       // send data
	ID=InCh();              // read ID
	S=InCh();               // read status
	return((ID<<8)+S);}     // return ID:S as 16-bit unsigned int

//  Program 14.6. 6811 code to output on the parallel network.
/* Port C output handshake tristate output example    */       
#define STAF 0x80
void main(void)
{   unsigned char Number;    
    DDRC = 0x00;      /* Port C are outputs, only when STRA=0 */
/*  STAI=0  no interrupts, 
    HNDS=1, OIN=1 output handshake mode
    CWOM=0  normal push/pull outputs on C 
    PLS=0   makes STRB a level output
    EGA=1   means STRA active on the rise  
    INVB=0  makes STRB=0 after write CL */
    PIOC = 0x1A;  
    Number=100; OutC(Number);  }
void OutC(unsigned char data) { 
    PORTCL=data;       /* set PortC flip flops, and make STRB=0  */
/* Port C data is driven only when STRA=0, otherwise Port C data=hiZ */
    while ((PIOC & STAF) == 0);  }  /* wait for rise of STRA */

//  Program 14.7. Bit fifo routines.
//********************GetTxBit************************
// returns TRUE=1 if successful, FALSE=0 if empty and data not removed
// output is boolean 0 means FALSE, nonzero is true
int GetTxBit (unsigned int *datapt) {
    if (SameBit(PutTxPt,GeTxtPt))
       return(0);       /* Failed, fifo was empty */
    else { 
       *datapt=(*GetTxPt.WPt)&GetTxPt.Mask;
       GetTxPt.Mask=GetTxPt.Mask>>1;
       if(GetTxPt.Mask==0) {
         GetTxPt.Mask=0x8000;
         ++GetTxPt.WPt;  // next word
         if((GetTxPt.WPt)==&TxFifo[FifoSize]) GetTxPt.WPt=&TxFifo[0];} // wrap
       return(1); }}