ax88796_16.c

/*! \file ax88796.c \brief ASIX AX88796 Ethernet Interface Driver. */
//*****************************************************************************
//
// File Name    : 'ax88796.c'
// Title        : ASIX AX88796 Ethernet Interface Driver
// Author       : Pascal Stang
// Created      : 10/22/2002
// Revised      : 8/21/2005
// Version      : 0.1
// Target MCU   : Atmel AVR series
// Editor Tabs  : 4
//
// Description  : This driver provides initialization and transmit/receive
//      functions for the ASIX AX88796 10/100Mb Ethernet Controller and PHY.
//
// Based in part on code by Louis Beaudoin (www.embedded-creations.com).
// Thanks to Adam Dunkels and Louis Beaudoin for providing the initial
// structure in which to write this driver.
//
//*****************************************************************************

#include "global.h"
#include "timer.h"
#include "rprintf.h"

#include "ax88796.h"

// include configuration
#include "ax88796conf.h"

// pointers to locations in the ax88796 receive buffer
static unsigned char NextPage;              // page pointer to next Rx packet
static unsigned int CurrentRetreiveAddress; // DMA address for read Rx packet location


void nicInit(void)
{
    ax88796Init();
}

void nicSend(unsigned int len, unsigned char* packet)
{
    ax88796BeginPacketSend(len);
    ax88796SendPacketData(packet, len);
    ax88796EndPacketSend();
}

unsigned int nicPoll(unsigned int maxlen, unsigned char* packet)
{
    unsigned int packetLength;
    
    packetLength = ax88796BeginPacketRetreive();

    // if there's no packet or an error - exit without ending the operation
    if( !packetLength )
        return 0;

    // drop anything too big for the buffer
    if( packetLength > maxlen )
    {
        ax88796EndPacketRetreive();
        return 0;
    }
    
    // copy the packet data into the uIP packet buffer
    ax88796RetreivePacketData( packet, packetLength );
    ax88796EndPacketRetreive();
        
    return packetLength;
}

void nicGetMacAddress(u08* macaddr)
{
    u08 tempCR;
    // switch register pages
    tempCR = ax88796Read(CR);
    ax88796Write(CR,tempCR|PS0);
    // read MAC address registers
    *macaddr++ = ax88796Read(PAR0);
    *macaddr++ = ax88796Read(PAR1);
    *macaddr++ = ax88796Read(PAR2);
    *macaddr++ = ax88796Read(PAR3);
    *macaddr++ = ax88796Read(PAR4);
    *macaddr++ = ax88796Read(PAR5);
    // switch register pages back
    ax88796Write(CR,tempCR);
}

void nicSetMacAddress(u08* macaddr)
{
    u08 tempCR;
    // switch register pages
    tempCR = ax88796Read(CR);
    ax88796Write(CR,tempCR|PS0);
    // write MAC address registers
    ax88796Write(PAR0, *macaddr++);
    ax88796Write(PAR1, *macaddr++);
    ax88796Write(PAR2, *macaddr++);
    ax88796Write(PAR3, *macaddr++);
    ax88796Write(PAR4, *macaddr++);
    ax88796Write(PAR5, *macaddr++);
    // switch register pages back
    ax88796Write(CR,tempCR);
}

void nicRegDump(void)
{
    ax88796RegDump();
}


void ax88796SetupPorts(void)
{
#if NIC_CONNECTION == MEMORY_MAPPED
    // enable external SRAM interface - no wait states
//  sbi(MCUCR, SRE);
//  sbi(MCUCR, SRW10);
//  sbi(XMCRA, SRW00);
//  sbi(XMCRA, SRW01);
//  sbi(XMCRA, SRW11);
#else
    // set address port to output
    AX88796_ADDRESS_DDR = AX88796_ADDRESS_MASK;
    
    // set data port to input with pull-ups
    AX88796_DATA_DDR = 0x00;
    AX88796_DATA_PORT = 0xFF;

    // initialize the control port read and write pins to de-asserted
    sbi( AX88796_CONTROL_PORT, AX88796_CONTROL_READPIN );
    sbi( AX88796_CONTROL_PORT, AX88796_CONTROL_WRITEPIN );
    // set the read and write pins to output
    sbi( AX88796_CONTROL_DDR, AX88796_CONTROL_READPIN );
    sbi( AX88796_CONTROL_DDR, AX88796_CONTROL_WRITEPIN );
#endif
    // set reset pin to output
//  sbi( AX88796_RESET_DDR, AX88796_RESET_PIN );
}


#if NIC_CONNECTION == MEMORY_MAPPED
inline void ax88796Write(u08 address, u08 data)
{
    *(volatile u08*)(AX88796_MEMORY_MAPPED_OFFSET + address) = data;
}
#else
void ax88796Write(u08 address, u08 data)
{
    // assert the address
    AX88796_ADDRESS_PORT = address | (AX88796_ADDRESS_PORT&~AX88796_ADDRESS_MASK);

    // set data bus as output and place data on bus
    AX88796_DATA_DDR = 0xFF;
    AX88796_DATA_PORT = data;
    
    // clock write pin
    cbi(AX88796_CONTROL_PORT, AX88796_CONTROL_WRITEPIN);
    nop();
    nop();
    sbi(AX88796_CONTROL_PORT, AX88796_CONTROL_WRITEPIN);
    
    // set data bus back to input with pullups enabled
    AX88796_DATA_DDR = 0x00;
    AX88796_DATA_PORT = 0xFF;
}
#endif


#if NIC_CONNECTION == MEMORY_MAPPED
inline u08 ax88796Read(u08 address)
{
    return *(volatile u08*)(AX88796_MEMORY_MAPPED_OFFSET + address);
}
#else
u08 ax88796Read(u08 address)
{
    u08 data;
   
    // assert the address
    AX88796_ADDRESS_PORT = address | (AX88796_ADDRESS_PORT&~AX88796_ADDRESS_MASK);

    // assert read
    cbi(AX88796_CONTROL_PORT, AX88796_CONTROL_READPIN);
    nop();
    nop();
    // read in the data
    data = AX88796_DATA_PIN;

    // negate read
    sbi(AX88796_CONTROL_PORT, AX88796_CONTROL_READPIN);

    return data;
}
#endif                       


void ax88796Init(void)
{
    unsigned char tcrFduFlag;
    
    // initialize I/O ports
    ax88796SetupPorts();

    // do a hard reset
//  sbi(AX88796_RESET_PORT, AX88796_RESET_PIN);
//  delay_ms(100);
//  cbi(AX88796_RESET_PORT, AX88796_RESET_PIN);

    // do soft reset
    ax88796Write(ISR, ax88796Read(ISR));
    delay_ms(50);

    // wait for PHY to come out of reset
    ax88796Read(RSTPORT);
    while(ax88796Read(TR) & RST_B);

    // if the phy has not completed autonegotiation,
    // power it down, wait 2.5sec, and then re-enable autonegotioation
    if(!(ax88796Read(TR) & AUTOD))
    {
        ax88796WriteMii(0x10,0x00,0x0800);
        delay_ms(2500);
        ax88796WriteMii(0x10,0x00,0x1200);
    }

    ax88796Write(CR,(RD2|STOP));        // stop the NIC, abort DMA, page 0
    delay_ms(5);                        // make sure nothing is coming in or going out
    ax88796Write(DCR,DCR_INIT);    
    ax88796Write(RBCR0,0x00);
    ax88796Write(RBCR1,0x00);
    ax88796Write(IMR,0x00);
    ax88796Write(ISR,0xFF);
    ax88796Write(RCR,0x20);
    ax88796Write(BNRY,RXSTART_INIT);
    ax88796Write(PSTART,RXSTART_INIT);
    ax88796Write(PSTOP,RXSTOP_INIT);
    
    // switch to page 1
    ax88796Write(CR,(PS0|RD2|STOP));
    // write mac address
    ax88796Write(PAR0, AX88796_MAC0);
    ax88796Write(PAR1, AX88796_MAC1);
    ax88796Write(PAR2, AX88796_MAC2);
    ax88796Write(PAR3, AX88796_MAC3);
    ax88796Write(PAR4, AX88796_MAC4);
    ax88796Write(PAR5, AX88796_MAC5);
    // set start point
    ax88796Write(CURR,RXSTART_INIT+1);

    ax88796Write(CR,(RD2|START));
    ax88796Write(RCR,RCR_INIT);

    if(ax88796Read(GPI) & I_SPD)        // check PHY speed setting
        tcrFduFlag = FDU;               // if 100base, do full duplex
    else
        tcrFduFlag = 0;                 // if 10base, do half duplex
        
    ax88796Write(TCR,(tcrFduFlag|TCR_INIT));

    ax88796Write(GPOC,MPSEL);           // select media interface
  
    ax88796Write(TPSR,TXSTART_INIT);

    ax88796Write(CR,(RD2|STOP));
    ax88796Write(DCR,DCR_INIT);
    ax88796Write(CR,(RD2|START));
    ax88796Write(ISR,0xFF);
    ax88796Write(IMR,IMR_INIT);
    ax88796Write(TCR,(tcrFduFlag|TCR_INIT));

    //test
/*
    while(1)
    {
        vt100SetCursorPos(18,0);
        ax88796RegDump();
    }
*/
}


void ax88796BeginPacketSend(unsigned int packetLength)
{
    unsigned int sendPacketLength;
    sendPacketLength = (packetLength>=ETHERNET_MIN_PACKET_LENGTH)?
                        (packetLength):(ETHERNET_MIN_PACKET_LENGTH);
    
    // start the NIC
    ax88796Write(CR,(RD2|START));
    
    // still transmitting a packet - wait for it to finish
    while( ax88796Read(CR) & TXP );

    //load beginning page for transmit buffer
    ax88796Write(TPSR,TXSTART_INIT);
    
    //set start address for remote DMA operation
    ax88796Write(RSAR0,0x00);
    ax88796Write(RSAR1,0x40);
    
    //clear the packet stored interrupt
    ax88796Write(ISR, PTX);

    //load data byte count for remote DMA
    ax88796Write(RBCR0, packetLength);
    ax88796Write(RBCR1, packetLength>>8);

    ax88796Write(TBCR0, sendPacketLength);
    ax88796Write(TBCR1, sendPacketLength>>8);
    
    //do remote write operation
    ax88796Write(CR,(RD1|START));
}


void ax88796SendPacketData(unsigned char *localBuffer, unsigned int length)
{
    unsigned int i;
    
    for(i=0;i<length;i++)
        ax88796Write(RDMAPORT, localBuffer[i]);
}


void ax88796EndPacketSend(void)
{
    // send the contents of the transmit buffer onto the network
    ax88796Write(CR,(RD2|TXP));
    
    // clear the remote DMA interrupt
    ax88796Write(ISR, RDC);
}


unsigned int ax88796BeginPacketRetreive(void)
{
    unsigned char writePagePtr;
    unsigned char readPagePtr;
    unsigned char bnryPagePtr;
    unsigned char i;
    
    unsigned char pageheader[4];
    unsigned int rxlen;
    
    // check for and handle an overflow
    ax88796ProcessInterrupt();
    
    // read CURR from page 1
    ax88796Write(CR,(PS0|RD2|START));
    writePagePtr = ax88796Read(CURR);
    // read the boundary register from page 0
    ax88796Write(CR,(RD2|START));
    bnryPagePtr = ax88796Read(BNRY);

    // first packet is at page bnryPtr+1
    readPagePtr = bnryPagePtr+1;
    if(readPagePtr >= RXSTOP_INIT) readPagePtr = RXSTART_INIT;
    
    // return if there is no packet in the buffer
    if( readPagePtr == writePagePtr )
    {
        return 0;
    }
    
    // clear the packet received interrupt flag
    ax88796Write(ISR, PRX);
    
    // if the boundary pointer is invalid,
    // reset the contents of the buffer and exit
    if( (bnryPagePtr < RXSTART_INIT) || (bnryPagePtr >= RXSTOP_INIT) )
    {
        ax88796Write(BNRY, RXSTART_INIT);
        ax88796Write(CR, (PS0|RD2|START));
        ax88796Write(CURR, RXSTART_INIT+1);
        ax88796Write(CR, (RD2|START));
        
//      rprintf("B");
        return 0;
    }

    // initiate DMA to transfer the RTL8019 packet header
    ax88796Write(RBCR0, 4);
    ax88796Write(RBCR1, 0);
    ax88796Write(RSAR0, 0);
    ax88796Write(RSAR1, readPagePtr);
    ax88796Write(CR, (RD0|START));
    for(i=0;i<4;i++)
        pageheader[i] = ax88796Read(RDMAPORT);

    // end the DMA operation
    ax88796Write(CR, (RD2|START));
    for(i = 0; i <= 20; i++)
        if(ax88796Read(ISR) & RDC)
            break;
    ax88796Write(ISR, RDC);
    
    rxlen = (pageheader[PKTHEADER_PKTLENH]<<8) + pageheader[PKTHEADER_PKTLENL];
    NextPage = pageheader[PKTHEADER_NEXTPAGE];
    
    CurrentRetreiveAddress = (readPagePtr<<8) + 4;
    
    // if the NextPage pointer is invalid, the packet is not ready yet - exit
    if( (NextPage >= RXSTOP_INIT) || (NextPage < RXSTART_INIT) )
    {
//      rprintf("N");
//      rprintfu08(nextPage);
        return 0;
    }

    return rxlen-4;
}


void ax88796RetreivePacketData(unsigned char * localBuffer, unsigned int length)
{
    unsigned int i;
    
    // initiate DMA to transfer the data
    ax88796Write(RBCR0, (unsigned char)length);
    ax88796Write(RBCR1, (unsigned char)(length>>8));
    ax88796Write(RSAR0, (unsigned char)CurrentRetreiveAddress);
    ax88796Write(RSAR1, (unsigned char)(CurrentRetreiveAddress>>8));
    ax88796Write(CR, (RD0|START));
    for(i=0;i<length;i++)
        localBuffer[i] = ax88796Read(RDMAPORT);

    // end the DMA operation
    ax88796Write(CR, (RD2|START));
    for(i = 0; i <= 20; i++)
        if(ax88796Read(ISR) & RDC)
            break;
    ax88796Write(ISR, RDC);
    
    CurrentRetreiveAddress += length;
    if( CurrentRetreiveAddress >= 0x6000 )
        CurrentRetreiveAddress -= (0x6000-0x4600) ;
}


void ax88796EndPacketRetreive(void)
{
    unsigned char i;
    unsigned char bnryPagePtr;

    // end the DMA operation
    ax88796Write(CR, (RD2|START));
    for(i = 0; i <= 20; i++)
        if(ax88796Read(ISR) & RDC)
            break;
    ax88796Write(ISR, RDC);

    // set the boundary register to point
    // to the start of the next packet-1
    bnryPagePtr = NextPage-1;
    if(bnryPagePtr < RXSTART_INIT) bnryPagePtr = RXSTOP_INIT-1;

    ax88796Write(BNRY, bnryPagePtr);
}


void ax88796ProcessInterrupt(void)
{
    unsigned char intr = ax88796Read(ISR);
    
    // check for receive overflow
    if( intr & OVW )
        ax88796ReceiveOverflowRecover();
}


void ax88796ReceiveOverflowRecover(void)
{
    // receive buffer overflow handling procedure
    // as specified in the AX88796 datasheet

    unsigned char cmdReg;
    unsigned char resend=0;

    // check if we were transmitting something
    cmdReg = ax88796Read(CR);
    // stop the interface
    ax88796Write(CR, (RD2|STOP));
    // wait for timeout
    delay_ms(2);
    // clear remote byte count registers
    ax88796Write(RBCR0, 0x00);
    ax88796Write(RBCR1, 0x00);
    
    // if we were transmitting something
    if(cmdReg & TXP)
    {
        // check if the transmit completed
        cmdReg = ax88796Read(ISR);
        if((cmdReg & PTX) || (cmdReg & TXE))
            resend = 0;     // transmit completed
        else
            resend = 1;     // transmit was interrupted, must resend
    }
    // switch to loopback mode
    ax88796Write(TCR, LB0);
    // start the interface
    ax88796Write(CR, (RD2|START));
    // set boundary
    ax88796Write(BNRY, RXSTART_INIT);
    // go to page 1
    ax88796Write(CR, (PS0|RD2|START));
    // set current page register
    ax88796Write(CPR, RXSTART_INIT+1);
    // go to page 0
    ax88796Write(CR, (RD2|START));
    // clear the overflow int
    ax88796Write(ISR, OVW);
    // switch to normal (non-loopback mode)
    ax88796Write(TCR, TCR_INIT);

    // if previous transmit was interrupted, then resend
    if(resend)
        ax88796Write(CR, (RD2|TXP|START));

    // recovery completed
}


#define set_mdc     ax88796Write(MEMR,ax88796Read(MEMR)|0x01);
#define clr_mdc     ax88796Write(MEMR,ax88796Read(MEMR)&0xFE);

#define mii_clk     set_mdc; clr_mdc;                 
                    
#define set_mdir    ax88796Write(MEMR,ax88796Read(MEMR)|0x02);
#define clr_mdir    ax88796Write(MEMR,ax88796Read(MEMR)&0xFD);
                    
#define set_mdo     ax88796Write(MEMR,ax88796Read(MEMR)|0x08)
#define clr_mdo     ax88796Write(MEMR,ax88796Read(MEMR)&0xF7)

#define mii_write   clr_mdo; mii_clk;   \
                    set_mdo; mii_clk;   \
                    clr_mdo; mii_clk;   \
                    set_mdo; mii_clk;

#define mii_read    clr_mdo; mii_clk;   \
                    set_mdo; mii_clk;   \
                    set_mdo; mii_clk;   \
                    clr_mdo; mii_clk;

#define mii_r_ta    mii_clk; mii_clk;

#define mii_w_ta    set_mdo; mii_clk;   \
                    clr_mdo; mii_clk;
            
void ax88796WriteMii(unsigned char phyad,unsigned char regad,unsigned int mii_data)
{
    unsigned char mask8;
    unsigned int  i,mask16;

    clr_mdir;
    mii_write;
 
    mask8 = 0x10;
    for(i=0;i<5;++i)
    {
        if(mask8 & phyad)
            set_mdo;
        else
            clr_mdo;
        mii_clk;
        mask8 >>= 1;     
    }   
    mask8 = 0x10;
    for(i=0;i<5;++i)
    {
        if(mask8 & regad)
            set_mdo;
        else
            clr_mdo;
        mii_clk;
        mask8 >>= 1;     
    }                       
    mii_w_ta;
 
    mask16 = 0x8000;
    for(i=0;i<16;++i)
    {
        if(mask16 & mii_data)
            set_mdo;
        else
            clr_mdo;
        mii_clk;     
        mask16 >>= 1;    
    }               
}
 
unsigned int ax88796ReadMii(unsigned char phyad,unsigned char regad)
{
    unsigned char mask8,i;
    unsigned int  mask16,result16;
 
    clr_mdir;
    mii_read;

    mask8 = 0x10;
    for(i=0;i<5;++i)
    {
        if(mask8 & phyad)
            set_mdo;
        else
            clr_mdo;
        mii_clk;     
        mask8 >>= 1;
    }
    mask8 = 0x10;
    for(i=0;i<5;++i)
    {
        if(mask8 & regad)
            set_mdo;
        else
            clr_mdo;
        mii_clk;
        mask8 >>= 1;
    }
            
    set_mdir;
    mii_r_ta;
 
    mask16 = 0x8000;
    result16 = 0x0000;
    for(i=0;i<16;++i)
    {
        if(ax88796Read(MEMR) & 0x04)
        {
            result16 |= mask16;
        }
        else
        {
            asm volatile ("nop");
            //break;
        }
        mii_clk;
        mask16 >>= 1;
    }
    return result16;
}


void ax88796RegDump(void)
{
    unsigned char result;
    result = ax88796Read(TR);
    
    rprintf("Media State: ");
    if(!(result & AUTOD))
        rprintf("Autonegotiation\r\n");
    else if(result & RST_B)
        rprintf("PHY in Reset   \r\n");
    else if(!(result & RST_10B))
        rprintf("10BASE-T       \r\n");
    else if(!(result & RST_TXB))
        rprintf("100BASE-T      \r\n");
                
    //rprintf("TR regsiter      : %x\r\n",result);
    //result = read_mii(0x10,0);
    //rprintf("MII regsiter 0x10: %x\r\n",result);

    rprintfProgStrM("Page0: CR  BNRY PSR PST ISR TSR RSR MMR TR  GPI\r\n");
    rprintfProgStrM("       ");
    rprintfu08(ax88796Read(CR));
    rprintfProgStrM("  ");
    rprintfu08(ax88796Read(BNRY));
    rprintfProgStrM("   ");
    rprintfu08(ax88796Read(PSTART));
    rprintfProgStrM("  ");
    rprintfu08(ax88796Read(PSTOP));
    rprintfProgStrM("  ");
    rprintfu08(ax88796Read(ISR));
    rprintfProgStrM("  ");
    rprintfu08(ax88796Read(TSR));
    rprintfProgStrM("  ");
    rprintfu08(ax88796Read(RSR));
    rprintfProgStrM("  ");
    rprintfu08(ax88796Read(MEMR));
    rprintfProgStrM("  ");
    rprintfu08(ax88796Read(TR));
    rprintfProgStrM("  ");
    rprintfu08(ax88796Read(GPI));
    rprintfCRLF();

    ax88796Write(CR,ax88796Read(CR)|PS0);

    rprintf("Page1: CR  PAR    CPR\r\n");
    rprintfProgStrM("       ");
    rprintfu08(ax88796Read(CR));
    rprintfProgStrM("  ");
    rprintfChar(ax88796Read(PAR0));
    rprintfChar(ax88796Read(PAR1));
    rprintfChar(ax88796Read(PAR2));
    rprintfChar(ax88796Read(PAR3));
    rprintfChar(ax88796Read(PAR4));
    rprintfChar(ax88796Read(PAR5));
    rprintfProgStrM(" ");
    rprintfu08(ax88796Read(CPR));
    
    ax88796Write(CR,ax88796Read(CR)&~PS0);

    delay_ms(25);
}

void ax88796PhyDump(void)
{
    rprintfProgStrM("----- AX88796 PHY INFO -----\r\n");
    rprintfProgStrM("MR 0 (Control)      = 0x"); rprintfu16( ax88796ReadMii(0x10, 0) ); rprintfCRLF();
    rprintfProgStrM("MR 1 (Status)       = 0x"); rprintfu16( ax88796ReadMii(0x10, 1) ); rprintfCRLF();
    rprintfProgStrM("MR 2 (PHY ID1)      = 0x"); rprintfu16( ax88796ReadMii(0x10, 2) ); rprintfCRLF();
    rprintfProgStrM("MR 3 (PHY ID2)      = 0x"); rprintfu16( ax88796ReadMii(0x10, 3) ); rprintfCRLF();
    rprintfProgStrM("MR 4 (AutoNeg Adv)  = 0x"); rprintfu16( ax88796ReadMii(0x10, 4) ); rprintfCRLF();
    rprintfProgStrM("MR 5 (AutoNeg Abil) = 0x"); rprintfu16( ax88796ReadMii(0x10, 5) ); rprintfCRLF();
    rprintfProgStrM("MR 6 (AutoNeg Exp)  = 0x"); rprintfu16( ax88796ReadMii(0x10, 6) ); rprintfCRLF();
    rprintfProgStrM("MR 7 (NextPg Tx)    = 0x"); rprintfu16( ax88796ReadMii(0x10, 7) ); rprintfCRLF();
    rprintfProgStrM("MR16 (PCS Ctrl)     = 0x"); rprintfu16( ax88796ReadMii(0x10,16) ); rprintfCRLF();
    rprintfProgStrM("MR17 (AutoNeg RegA) = 0x"); rprintfu16( ax88796ReadMii(0x10,17) ); rprintfCRLF();
    rprintfProgStrM("MR18 (AutoNeg RegB) = 0x"); rprintfu16( ax88796ReadMii(0x10,18) ); rprintfCRLF();
    rprintfProgStrM("MR19 (Analog Test)  = 0x"); rprintfu16( ax88796ReadMii(0x10,19) ); rprintfCRLF();
    rprintfProgStrM("MR21 (RXERR count)  = 0x"); rprintfu16( ax88796ReadMii(0x10,21) ); rprintfCRLF();
    rprintfProgStrM("MR28 (Status Reg)   = 0x"); rprintfu16( ax88796ReadMii(0x10,28) ); rprintfCRLF();
    rprintfProgStrM("MR29 (100Mbs Ctrl)  = 0x"); rprintfu16( ax88796ReadMii(0x10,29) ); rprintfCRLF();
    rprintfProgStrM("MR30 (10Mbs Ctrl)   = 0x"); rprintfu16( ax88796ReadMii(0x10,30) ); rprintfCRLF();
    rprintfProgStrM("MR31 (Quick Status) = 0x"); rprintfu16( ax88796ReadMii(0x10,31) ); rprintfCRLF();
}


/*
unsigned char ax88796ReceiveEmpty(void)
{
    unsigned char temp;

    // read CPR from page 1
    ax88796Write(CR,0x62);
    temp = ax88796Read(CPR);
    
    // return to page 0
    ax88796Write(CR,0x22);
    
    return ( ax88796Read(BNRY) == temp );
    
}*/

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