async.c

pic单片机驱动mcp2510源代码

#include <pic.h>
#include "..\inc\async.h"

/* Routines for initialisation and use of the SCI
 * for the PIC processor.
 */

void async_Init()
{
    /*
    This is a list of different settings in SPREG at FOSC 4 and 16 MHZ
    Baudrate     4      16
    9600         25     103
    19200        12     51
    38400        5.5    25
*/  
//    SPBRG = 25;   /* set the baud rate 9600 at 4 MHz */
//    TXSTA = 0x24; /* TXEN and BRGH=1 */
//    RCSTA = 0x90; /* SPEN=1, CREN=1,  */
//    TXIE = 0; /* disable tx interrupts in PIE1 register */
//    RCIE = 0; /* disable rx interrupts in PIE1 register */

    SPBRG = 12;   /* set the baud rate 9600 at 4 MHz */
    TXSTA = 0x20; /* TXEN and BRGH=1 */
    RCSTA = 0x80; /* SPEN=1, CREN=1,  */
    TXIE = 0; /* disable tx interrupts in PIE1 register */
    RCIE = 0; /* disable rx interrupts in PIE1 register */
}

//void async_PutByte(unsigned char byte)
void putch(unsigned char byte) // This will make printf() use our routine
{
    while(!TXIF)  /* set when register is empty */
        continue;
    TXREG = byte;

    return;
}


/* Will wait until a character is received and return the character.
If error condition is to be checked, do that ahead of this function */

unsigned char async_GetByte(void)
{
    while(!RCIF)  /* set when register is not empty */
        continue;

    return RCREG; /* RXD9 and FERR are gone now */
}

/* Check if there is an overrun condition if so remove the condition
return OVERRUN if error othervise OK   */ 
unsigned char async_CheckOERR(void)
{
    if(OERR)  /* re-enable after overrun error */
    {
        CREN = 0;
        CREN = 1;
        return 1;
    }

    return 0;
}


/* Wait forever for a character to be recieved  */

unsigned char async_GetFERR(void) 
{
    while(!RCIF)
        continue;

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