;
; UART串口实验
;GPBCON        EQU        0x56000010
GPBDAT        EQU        0x56000014AREA Init, CODE, READONLYENTRY
start
; close watchdogldr r0, = 0x53000000    ; 将看门狗控制寄存器地址放入r0mov r1, #0str r1, [r0]            ; 设置看门狗控制寄存器的值为0bl initmem                ; 跳转到initmem代码段，初始化内存IMPORT xmain            ; 引入main.c中的xmain函数ldr sp, =0x34000000        ; 调用C程序之前先初始化栈指针ldr lr, =loop            ; 设置xmain函数的返回地址ldr pc, =xmain            ; 跳转到C程序中的xmain函数的入口处执行loopb loop                    ; 死循环initmem                        ; 内存初始化ldr r0, =0x48000000        ; 加载内存相关寄存器首地址r0ldr r1, =0x48000034        ; 加载内存相关寄存器尾地址到r1adr r2, memdata            ; 将寄存器配置数据地址段首地址加载到r2initmemloopldr r3, [r2], #4        ; 循环设置存寄存器str r3, [r0], #4teq r0, r1bne initmemloop            ; 循环到最后一个寄存器时退出函数bx  lrmemdataDCD    0x22000000         ;BWSCONDCD    0x00000700        ;BANKCON0    DCD    0x00000700        ;BANKCON1    DCD    0x00000700        ;BANKCON2    DCD    0x00000700      ;BANKCON3        DCD    0x00000700        ;BANKCON4    DCD    0x00000700        ;BANKCON5    DCD    0x00018005        ;BANKCON6    DCD    0x00018005        ;BANKCON7    DCD    0x008e07a3        ;REFRESH    DCD    0x000000b1        ;BANKSIZE    DCD    0x00000030        ;MRSRB6    DCD    0x00000030        ;MRSRB7END

init.s

 1 /* xmain.c */
 2
 3 /* GPIO registers */
 4 #define    GPHCON                (*(volatile unsigned long *)0x56000070)
 5 #define    GPHDAT                (*(volatile unsigned long *)0x56000074)
 6 #define    GPHUP                (*(volatile unsigned long *)0x56000078)
 7
 8 /*UART registers*/
 9 #define    ULCON0                (*(volatile unsigned long *)0x50000000)
10 #define    UCON0                (*(volatile unsigned long *)0x50000004)
11 #define    UFCON0                 (*(volatile unsigned long *)0x50000008)
12 #define    UMCON0                (*(volatile unsigned long *)0x5000000c)
13 #define    UTRSTAT0            (*(volatile unsigned long *)0x50000010)
14 #define    UTXH0                 (*(volatile unsigned char *)0x50000020)
15 #define    URXH0                 (*(volatile unsigned char *)0x50000024)
16 #define    UBRDIV0                (*(volatile unsigned long *)0x50000028)
17
18 #define    TXD0READY    (1<<2)  //发送数据状态OK
19 #define    RXD0READY    (1)        //接收数据状态OK
20
21 /* UART串口初始化 */
22 void uart_init( )
23 {
24     GPHCON |= 0xa0;        //GPH2,GPH3 used as TXD0,RXD0
25     GPHUP     = 0x0;        //GPH2,GPH3内部上拉
26     ULCON0     = 0x03;    //8N1
27     UCON0     = 0x05;    //查询方式为轮询或中断;时钟选择为PCLK
28     UFCON0 = 0x00;        //不使用FIFO
29     UMCON0 = 0x00;        //不使用流控
30     UBRDIV0 = 12;        //波特率为57600,PCLK=12Mhz
31 }
32
33 /* UART串口单个字符打印函数 */
34 extern void putc(unsigned char c)
35 {
36     while( ! (UTRSTAT0 & TXD0READY) );
37     UTXH0 = c;
38 }
39
40 /* UART串口接受单个字符函数 */
41 extern unsigned char getc(void)
42 {
43     while( ! (UTRSTAT0 & RXD0READY) );
44     return URXH0;
45 }
46
47 /* UART串口字符串打印函数 */
48 extern int printk(const char* str)
49 {
50     int i = 0;
51     while( str[i] ){
52         putc( (unsigned char) str[i++] );
53     }
54     return i;
55 }
56
57 __inline void delay(int msec)
58 {
59     int i, j;
60     for(i = 1000; i > 0; i--)
61         for(j = msec*10; j > 0; j--)
62             /* do nothing */;
63 }
64
65 /* xmain 通过UART串口打印字符串 */
66 int xmain()
67 {
68     uart_init();
69     while(1)
70     {
71         delay(10);
72         printk("Uart串口打印试验\r\n");
73     }
74    //  return 0;    这句省去，这样 就不会出现  statement is unreachable
75 }