The new uart0 communication baud rate is inconsistent (the baud rate is reduced by 4 times)

If Keil arm is used, vpbdiv = 0x00000000 is automatically generated in startup. S, which leads to fpclk dividing by 4. The baud rate is reduced by four times. The default value of startup. s in Keil is as follows .; // <E> vpbdiv setup
; // <I> Peripheral Bus clock rate
; // <O1.0.. 1> vpbdiv: VPB clock
; // <0 => VPB clock = CPU clock/4
; // <1 => VPB clock = CPU clock
; // <2 => VPB clock = CPU clock/2
; // <O1.4.. 5> xclkdiv: xclk pin
; // <0 => xclk pin = CPU clock/4
; // <1 => xclk pin = CPU clock
; // <2 => xclk pin = CPU clock/2
; // </E>
Vpbdiv_setup equ 0vpbdiv_val equ 0x00000000 we will change it:

Vpbdiv_setup equ 1

Vpbdiv_val equ 0x00000001

Solve the problem.

1. # Include <lpc20.x. h>
2. # Include "config. H"
4. # Define uart_baud (baud) (unsigned INT) (fosc * pll_m)/(baud * 16 ))
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;
14. U0lcr = 0x03;/* dlab = 0 */
15. }
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
29. While (u0lsr & 0x40) = 0); // wait for the 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. {
40. Init_uart0 (uart_baud (115200 ));
42. For (;;)
43. {
44. Sent_str ("www.dnp.cn/N ");
45. Delay (200 );
46. }
47. }