1: #include <pic.h>

     2: #include "sci.h"

     3: 

     4: /* Routines for initialisation and use of the SCI

     5:  * for the PIC processor.

     6:  */

     7: 

     8: /* other options:

     9:  * frame errors

    10:  */

    11: 

    12: unsigned char

    13: sci_Init(unsigned long int baud, unsigned char ninebits)

    14: {

    15:         int X;

    16:         unsigned long tmp;

    17:         

    18:         /* calculate and set baud rate register */

    19:         /* for asynchronous mode */

    20:         tmp = 16UL * baud;

    21:         X = (int)(FOSC/tmp) - 1;

    22:         if((X>255) || (X<0))

    23:         {

    24:                 tmp = 64UL * baud;

    25:                 X = (int)(FOSC/tmp) - 1;

    26:                 if((X>255) || (X<0))

    27:                 {

    28:                         return 1;       /* panic - baud rate unobtainable */

    29:                 }

    30:                 else

    31:                         BRGH = 0;       /* low baud rate */

    32:         }

    33:         else

    34:                 BRGH = 1;       /* high baud rate */

    35:         SPBRG = X;      /* set the baud rate */

    36: 

    37:         SYNC = 0;       /* asynchronous */

    38:         SPEN = 1;       /* enable serial port pins */

    39:         CREN = 1;       /* enable reception */

    40:         SREN = 0;       /* no effect */

    41:         TXIE = 0;       /* disable tx interrupts */

    42:         RCIE = 0;       /* disable rx interrupts */

    43:         TX9  = ninebits?1:0;    /* 8- or 9-bit transmission */

    44:         RX9  = ninebits?1:0;    /* 8- or 9-bit reception */

    45:         TXEN = 1;       /* enable the transmitter */

    46: 

    47:         return 0;

    48: }

    49: 

    50: void

    51: sci_PutByte(unsigned char byte)

    52: {

    53:         while(!TXIF)    /* set when register is empty */

    54:                 continue;

    55:         TXREG = byte;

    56: 

    57:         return;

    58: }

    59: 

    60: unsigned char

    61: sci_GetByte(void)

    62: {

    63:         while(!RCIF)    /* set when register is not empty */

    64:                 continue;

    65: 

    66:         return RCREG;   /* RXD9 and FERR are gone now */

    67: }

    68: 

    69: unsigned char

    70: sci_CheckOERR(void)

    71: {

    72:         if(OERR)        /* re-enable after overrun error */

    73:         {

    74:                 CREN = 0;

    75:                 CREN = 1;

    76:                 return 1;

    77:         }

    78:         

    79:         return 0;

    80: }

    81: 

    82: #define sci_PutNinth(bitnine)   (TX9D = bitnine?1:0;)

    83: 

    84: unsigned char

    85: sci_GetNinth(void)

    86: {

    87:         while(!RCIF)

    88:                 continue;

    89:         

    90:         return RX9D;    /* RCIF is not cleared until RCREG is read */

    91: }

    92: 

    93: unsigned char

    94: sci_GetFERR(void)

    95: {

    96:         while(!RCIF)

    97:                 continue;

    98:         

    99:         return FERR;    /* RCIF is not cleared until RCREG is read */

   100: }

   101: