Lpc2000

Hi,

I've the same pb few month aog. I do this and it's work fine. I hope this
exemple help you.

Regards,
Sebastien Jacquemard


#define EN_TXD1  0x00010000
#define EN_RXD1  0x00040000
#define SENS  0x00000400 //P0.10 = Rs485 sens
#define Txd         1       // RS485 : mode transmission
#define Rxd         0       // RS485 : mode r\ufffdception
#define TXD_BREAK 0x40 // Set TXD break


void init_rs485()
{
 IOSET0=SENS; //SENS=TXD

 PINSEL0 |= EN_RXD1 | EN_TXD1;          // Enable RxD1 and TxD1
   U1LCR = 0x8B;                          // 8 bits, Odd parity, 1 Stop bit
   U1DLL = Baud187500;
   U1LCR &= 0x7F;                         // DLAB = 0
}


void trasnmit_rs485(uchar *p)
{
 uchar n;
 uchar pause;


 IOSET0=SENS; //SENS=Txd --> rs485 in tx mode
 U1LCR|=TXD_BREAK; //break on txd1 line
 tempo(110); //tempo 90usec
 U1LCR&=~TXD_BREAK; //clear break


 n=*p++;
 do{
  while (!(U1LSR & 0x20)) watchdog(); //wait tx buffer empty
  U1THR = *p++;
 } while (--n);

 //wait buffer empty before swith in rx mode
 while ((U1LSR & 0x60)!=0x60) watchdog();
 IOCLR0=SENS; //SENS=Rxd --> rs485 in rx mode}
}

uchar receive_rs485(uchar *p)
{
 uchar n;
 uint fin;

 IOCLR0=SENS; //SENS=Rxd --> rs485 in rx mode

 n=*p;    // number of char to receive
 fin=100000;

 do{
  do{
   if (!fin)
   {
    IOSET0=SENS; //SENS=Txd --> rs485 in tx mode
    return(0);
   }
   fin--;
   watchdog();
  } while(!(U1LSR & 0x01)); //wait char
  *p++=U1RBR;   // store char
 } while(--n);

 IOSET0=SENS; //SENS=Txd --> rs485 in tx mode
 return(1);
}