(no subject) - test-drb@ccmp.vtda.org

10 Apr 2001

Thats pretty bizzare looking if it's for 8251 and the cmos cousin.
You sure you not talking to something else as 8251s were never 153kb/s
and I doubt the cmos parts were much faster.  The addresses seems strange
but that may be an interface oddity.  Also most 8251s needed a few reads
in the init after reset to clean them out.

Allison

-----Original Message-----
From: Mekonnen Tekeste &lt;M.Tekeste(a)Bradford.ac.uk&gt;
To: classiccmp(a)classiccmp.org &lt;classiccmp(a)classiccmp.org&gt;
Date: Tuesday, April 10, 2001 8:26 AM

...

Can Any one help me please? i am trying to interface a bar code reader
to PCI Bus via a 82C51 (UART), and i wrote a code to support my
hardware design but the software it seem wrong. Here is the code:

#include <conio.h>
#include <stdio.h>
#include <dos.h>

/* Type Definitions */

typedef   unsigned char   UBYTE;  /* Old habbit...     */

/* Serial Port Definitions */

#define   STATUS    0x308       /* Status Base Address */
#define   CONTROL   0x300       /* Control Base Address */
#define   TXREG     0x30C       /* Transmit Base Address */
#define   RXREG     0x304       /* Receive Base Address */
#define   TRUE 1

/* Function Prototypes */

void  InitUSART(void);            /* Initialize USART  */
void  TxData(UBYTE);              /* Transmit Data     */
UBYTE RxData(void);               /* Receive  Data     */

/*
   InitUSART() - Initialize USART to 153600, 8 Data Bits, No Parity, 1 Stop
...
 Bit
*/
void InitUSART(void)
{
  outp(CONTROL, 0x40); // Reset UART
  outp(CONTROL, 0x4E);          // Stop, no parity, 8-bit, %16 baud
  outp(CONTROL, 0x05);          // UART now ready
}

/*
   TxData() - Send Data to Serial Port
   Entry:
      data = Data to transmit
*/
void TxData(UBYTE data)
{
  UBYTE x;

  /* Check for Tx Buffer Empty */
  do
  {
    x = inp(STATUS);
    x &= 0x01;
  } while(x == 0);

  outp(TXREG, data);       /* Send Data */
}

/*
   RxData() - Receive Data from the Serial Port
   Exit:
      data = Rx Data byte
*/
UBYTE RxData(void)
{
  UBYTE x;
  UBYTE data = 0;

 while(TRUE)                     /* Check for Rx Data */
  {
    x = inp(STATUS);
    x &= 0x02;
    if(x == 0x02)
    {
      data = inp(RXREG);   /* Get Data          */
      break;
    }

    /* Optional. Aborts if keypress */

    if(kbhit())                   /* Abort if Keypress */
    {
      getch();
      printf("\n");
      break;
    }
  }
  return(data);
}

void main(void)
{

InitUSART();

while(TRUE)
  putch(RxData());
}