S3c2410裸板程序入门串口

流水灯跑起来了，是不是有点小兴奋，一鼓作气再来玩玩其他的，用PC机写程序，出了问题可以用perror等打印出信息，给调试带来了很大方便，可是板子上没有显示屏，没法打印怎么办？这次就写一个通过串口向PC机串口调试终端打印信息的小程序，方便以后的调试。串口通信的基本知识就不说了哈，网上很多的，直接上代码：

uart.c

 1 #include "s3c2410.h"
 2 
 3 void uart_sendchar(char a)
 4 {
 5     if(a == '\n'){
 6         while( !(UTRSTAT0 & (0x1<<2)) );
 7         UTXH0 = '\r';
 8     }
 9     while( !(UTRSTAT0 & (0x1<<2)) );
10     UTXH0 = a;
11 }
12 
13 void sendstring(const char *str)
14 {
15     while(*str){
16         uart_sendchar(*str);
17         str++;
18     }
19 }
20 
21 void uart_init()
22 {
23     GPHCON = (GPHCON & ~(0xf<<4)) | (0xa<<4);
24 
25     ULCON0 = 0x3;
26     UCON0 = 0x5;
27 
28     UBRDIV0 = (int)(PCLK/(115200*16)) - 1;
29 
30 }

GPHCON配置使用串口0， ULCON0 = 0X3配置串口使用8位数据位，一位停止位，无校验，UCON0 = 0X5设置传输模式，默认时钟使用PCLK。UTXH0为发送buffer, 往其中写数据后发送，UTRSTAT0检测数据线上有无数据，从而控制在一个字符发送完成后再发下一个。

还有注意\n的处理，因为windows的回车是\r\n，所以有单独的判断。

哦，你可能会问这个s3c2410.h在哪里，哦，这个其实是板子带的，就是定义了一堆寄存器地址，完全也可以自己定义。向这种格式：

s3c2410.h

 1 /* WOTCH DOG register */

 2 #define     WTCON       (*(volatile unsigned long *)0x53000000)

 3 #define     WTDAT       (*(volatile unsigned long *)0x53000004)

 4 #define     WTCNT       (*(volatile unsigned long *)0x53000008)

 5 

39 /*UART registers*/

40 #define ULCON0      (*(volatile unsigned long *)0x50000000)

41 #define UCON0       (*(volatile unsigned long *)0x50000004)

42 #define UFCON0      (*(volatile unsigned long *)0x50000008)

43 #define UMCON0      (*(volatile unsigned long *)0x5000000c)

44 #define UTRSTAT0    (*(volatile unsigned long *)0x50000010)

45 #define UTXH0       (*(volatile unsigned char *)0x50000020)

46 #define URXH0       (*(volatile unsigned char *)0x50000024)

47 #define UBRDIV0     (*(volatile unsigned long *)0x50000028)

48 

49 

50 /*interrupt registes*/

51 #define SRCPND      (*(volatile unsigned long *)0x4A000000)

52 #define INTMOD      (*(volatile unsigned long *)0x4A000004)

53 #define INTMSK      (*(volatile unsigned long *)0x4A000008)

54 #define PRIORITY        (*(volatile unsigned long *)0x4A00000c)

55 #define INTPND      (*(volatile unsigned long *)0x4A000010)

56 #define INTOFFSET       (*(volatile unsigned long *)0x4A000014)

57 #define SUBSRCPND       (*(volatile unsigned long *)0x4A000018)

58 #define INTSUBMSK       (*(volatile unsigned long *)0x4A00001c)

59 

60 /*external interrupt registers*/

61 #define EINTMASK        (*(volatile unsigned long *)0x560000a4)

62 #define EINTPEND        (*(volatile unsigned long *)0x560000a8)

63 

64 #define EXTINT2     (*(volatile unsigned long *)0x56000090)

65 

66 /*clock registers*/

67 #define LOCKTIME        (*(volatile unsigned long *)0x4c000000)

68 #define MPLLCON     (*(volatile unsigned long *)0x4c000004)

69 #define UPLLCON     (*(volatile unsigned long *)0x4c000008)

70 #define CLKCON      (*(volatile unsigned long *)0x4c00000c)

71 #define CLKSLOW     (*(volatile unsigned long *)0x4c000010)

72 #define CLKDIVN     (*(volatile unsigned long *)0x4c000014)

73 

74 

75 /*PWM & Timer registers*/

76 #define TCFG0       (*(volatile unsigned long *)0x51000000)

77 #define TCFG1       (*(volatile unsigned long *)0x51000004)

78 #define TCON        (*(volatile unsigned long *)0x51000008)

79 #define TCNTB0      (*(volatile unsigned long *)0x5100000c)

80 #define TCMPB0      (*(volatile unsigned long *)0x51000010)

81 #define TCNTO0      (*(volatile unsigned long *)0x51000014)

82 /* frequecy */

^M

83 #define FCLK        (202800000)

84 #define HCLK        (FCLK/2)

85 #define PCLK        (FCLK/4)

注意要用volatile 和 unsigned 来保证优化和移位不会处差错。