51单片机使用串口printf

#define BIT(x)                  ((unsigned int)((unsigned int)1<<x))

串口初始化

/*----------------------------------------------------------------------------*/
/*----------------------------------------------------------------------------*/
void Uart0_Init(unsigned int baud)
{
    unsigned long tmp;
    
#if 0
    P2CR  &= ~BIT(0);    //Input Mode
    P2PCR |= BIT(0);    //Enable pull-up resistor
    P2    |= BIT(0);
    
    P2CR  |=   BIT(1);  //Output Mode
    P2PCR &= ~(BIT(1)); //Disable pull-up resistor
    P2    |=   BIT(1);
#endif
    
    /* Config Uart0：Mode 1, 8-bits asynchronous. */
    SCON = 0x50;
    PCON |=0x80;            //Double baud rate
    tmp = 16000000/16/baud; //16000000UL*2/2/16/baud;
    tmp = 65536 - tmp;
    
    RCLK = 0;               //T4 create rxd baud rate
    TCLK = 0;               //T4 create txd baud rate
    
    _push_(INSCON);
    Select_Bank1();
    T4CLKS = 0;             //T4 Clock select = Sysclk = 16MHz;
    T4PS1 = 0;              //T4 Prescaler = 1/1;
    T4PS0 = 0;
    T4M1 = 0;               //T4 mode select bits = 01, T4 as Baud rate generator.
    T4M0 = 1;
    TL4 = (unsigned char)tmp;
    TH4 = (unsigned char)(tmp>>8);
    TR4 = 1;
    Select_Bank0();
    _pop_(INSCON);
    
    REN = 1;                //Enable Receive
    
    //ES0 = 1;              //Enable Uart0 Interrupt
    //TI = 1;               //printf need
}

printf重映射

/*----------------------------------------------------------------------------*/
//printf call
/*----------------------------------------------------------------------------*/
char putchar(char ch)
{
    //ES=0;  //Disable Uart0 Interrupt
    TI = 0;
    SBUF = (unsigned char)ch;
    while (!TI);
    TI = 0;
    //ES=1;   //Enable Uart0 Interrupt
    return (ch);
}