The baud rate of the newly created UART0 communication is inconsistent (the baud rate is reduced by 4 times)

If you use Keil ARM, the default value of VPBDIV=0X00000000 in the automatically generated Startup.s will result in Fpclk being divided by 4, which will cause the baud rate to drop by four times. The following are the default values ​​set in Startup.s in Keil. ;// VPBDIV Setup
;// Peripheral Bus Clock Rate
;// VPBDIV: VPB Clock
;// <0=> VPB Clock = CPU Clock / 4
;// <1=> VPB Clock = CPU Clock
;// <2=> VPB Clock = CPU Clock / 2
;// XCLKDIV: XCLK Pin
;// <0=> XCLK Pin
= CPU Clock / 4;// < 1=> XCLK
Pin = CPU Clock;// <2=>

VPBDIV_SETUP EQU 1

VPBDIV_Val EQU 0x00000001

problem solved.

1. #include

2. #include "Config.H"

3. 
   

4. #define UART_BAUD(baud) (unsigned int)((FOSC*PLL_M) / (baud * 16))

5. 
   

6. void Init_Uart0(unsigned int Baud)

7.  {

8.    /* initialize the serial interface */

9.   PINSEL0 = 0x00000005; /* Enable RxD0 and TxD0 */

10.   U0LCR = 0x83; /* 8 bits, no Parity, 1 Stop bit */

11.   U0DLM=(unsigned char)(Baud>>8);

12.   U0DLL = (unsigned char)Baud;                     

13.   

14.   U0LCR = 0x03; /* DLAB = 0 */

15.  }

16. 
    

17. void delay (unsigned int i) { /* Delay function */

18. unsigned int n;

19. while(i>1)

20. {

21.     for(n=65535;n>1;n--);

22.     i--;

23. }

24. }

25. void Sent_Byte(unsigned char data)

26. {  

27.     U0THR = data; // Send data

28. 
    

29.    while( (U0LSR&0x40)==0 ); // Wait for data to be sent

30. }

31. void Sent_Str(unsigned char const *str)

32. { while(1)

33.    { if( *str == '/0' ) break;

34.       Sent_Byte(*str++); // Send data

35.    }

36. }

37.  void main(void)

38.  {

39.     

40.      Init_Uart0(UART_BAUD(115200));

41.     

42.      for(;;)

43.      {

44.         Sent_Str("www.dnp.cn /n");

45.         delay(200);

46.      }

47.  }