/* --- STC12C5Axx Series MCU UART2 (8-bit/9-bit)Demo ---------------*/


#include "reg51.h"
#include "intrins.h"

typedef unsigned char BYTE;
typedef unsigned int WORD;

#define FOSC 11059200L      //System frequency
#define BAUD 115200         //UART baudrate

/*Define UART parity mode*/
#define NONE_PARITY     0   //None parity
#define ODD_PARITY      1   //Odd parity
#define EVEN_PARITY     2   //Even parity
#define MARK_PARITY     3   //Mark parity
#define SPACE_PARITY    4   //Space parity

#define PARITYBIT EVEN_PARITY   //Testing even parity

/*Declare SFR associated with the UART2 */
sfr AUXR  = 0x8e;           //Auxiliary register
sfr S2CON = 0x9a;           //UART2 control register
sfr S2BUF = 0x9b;           //UART2 data buffer
sfr BRT   = 0x9c;           //Baudrate generator
sfr IE2   = 0xaf;           //Interrupt control 2

#define S2RI  0x01          //S2CON.0
#define S2TI  0x02          //S2CON.1
#define S2RB8 0x04          //S2CON.2
#define S2TB8 0x08          //S2CON.3

bit busy;

void SendData(BYTE dat);
void SendString(char *s);

void main()
{
#if (PARITYBIT == NONE_PARITY)
    S2CON = 0x50;           //8-bit variable UART
#elif (PARITYBIT == ODD_PARITY) || (PARITYBIT == EVEN_PARITY) || (PARITYBIT == MARK_PARITY)
    S2CON = 0xda;           //9-bit variable UART, parity bit initial to 1
#elif (PARITYBIT == SPACE_PARITY)
    S2CON = 0xd2;           //9-bit variable UART, parity bit initial to 0
#endif

    BRT = -(FOSC/32/BAUD);  //Set auto-reload vaule of baudrate generator
    AUXR = 0x14;            //Baudrate generator work in 1T mode
    IE2 = 0x01;             //Enable UART2 interrupt
    EA = 1;                 //Open master interrupt switch

    SendString("STC12C5A60S2\r\nUart2 Test !\r\n");
    while(1);
}

/*----------------------------
UART2 interrupt service routine
----------------------------*/
void Uart2() interrupt 8 using 1
{
    if (S2CON & S2RI)
    {
        S2CON &= ~S2RI;     //Clear receive interrupt flag
        P0 = S2BUF;         //P0 show UART data
        P2 = (S2CON & S2RB8);//P2.2 show parity bit
    }
    if (S2CON & S2TI)
    {
        S2CON &= ~S2TI;     //Clear transmit interrupt flag
        busy = 0;           //Clear transmit busy flag
    }
}

/*----------------------------
Send a byte data to UART
Input: dat (data to be sent)
Output:None
----------------------------*/
void SendData(BYTE dat)
{
    while (busy);           //Wait for the completion of the previous data is sent
    ACC = dat;              //Calculate the even parity bit P (PSW.0)
    if (P)                  //Set the parity bit according to P
    {
#if (PARITYBIT == ODD_PARITY)
        S2CON &= ~S2TB8;    //Set parity bit to 0
#elif (PARITYBIT == EVEN_PARITY)
        S2CON |= S2TB8;     //Set parity bit to 1
#endif
    }
    else
    {
#if (PARITYBIT == ODD_PARITY)
        S2CON |= S2TB8;     //Set parity bit to 1
#elif (PARITYBIT == EVEN_PARITY)
        S2CON &= ~S2TB8;    //Set parity bit to 0
#endif
    }
    busy = 1;
    S2BUF = ACC;            //Send data to UART2 buffer
}

/*----------------------------
Send a string to UART
Input: s (address of string)
Output:None
----------------------------*/
void SendString(char *s)
{
    while (*s)              //Check the end of the string
    {
        SendData(*s++);     //Send current char and increment string ptr
    }
}