OK6410笔记 -- UART串口（OK6410上测试成功）

完成功能：编写串口程序，波特率为115200.当在pc终端上输入一个字符的时候，返回来该字符加1之后的值，比如按下1则返回2，按下a则返回b。

start.S

   
   
   
   

    
    
    
    
     1 
    
    
    
    .globl _start 
    
    
    
     2 
    
    
    
    
    
    
    
    _start:
    
    
    
     
    
    
    
     3 
    
    
    
     
    
    
    
     4 
    
    
    
    /* 硬件相关的设置 */ 
    
    
    
     5 
    
    
    
     /* Peri port setup */ 
    
    
    
     6 
    
    
    
     ldr r0, =0x70000000 
    
    
    
     7 
    
    
    
     orr r0, r0, #0x13 
    
    
    
     8 
    
    
    
     mcr p15,
    
    
    
    0
    
    
    
    ,r0,c15,c2,
    
    
    
    4
    
    
    
     @ 256M(0x70000000-0x7fffffff) 
    
    
    
     9 
    
    
    
     
    
    
    
    10 
    
    
    
    /* 关看门狗 */ 
    
    
    
    11 
    
    
    
    /* 往WTCON(0x7E004000)写0 */ 
    
    
    
    12 
    
    
    
     
    
    
    
    13 
    
    
    
     ldr r0, =0x7E004000 
    
    
    
    14 
    
    
    
     
    
    
    
    mov
    
    
    
     r1, #
    
    
    
    0
    
    
    
     
    
    
    
    15 
    
    
    
     
    
    
    
    str
    
    
    
     r1, [r0] 
    
    
    
    16 
    
    
    
     
    
    
    
    17 
    
    
    
     /* 设置栈 */ 
    
    
    
    18 
    
    
    
     ldr sp, =
    
    
    
    8
    
    
    
    *
    
    
    
    1024
    
    
    
     
    
    
    
    19 
    
    
    
     
    
    
    
    20 
    
    
    
     /* 设置时钟 */ 
    
    
    
    21 
    
    
    
     bl clock_init 
    
    
    
    22 
    
    
    
     
    
    
    
    23 
    
    
    
     bl main 
    
    
    
    24 
    
    
    
    
    
    
    
    halt:
    
    
    
     
    
    
    
    25 
    
    
    
     b halt 
    
    
    
    26 
    
    
    
    
   
   
   
   

波特率的时钟是建立在别的时钟基础上的，我这里选择的是PCLK，所以先得配置好PCLK的频率，下面的程序配置PCLK为50MHz，不要弄错了，否则最后算的波特率也是错误的，结果就会出错。

clock.c

   
   
   
   

    
    
    
    
     1 
    
    
    
    #define
    
    
    
     APLL_LOCK (*((volatile unsigned long *)0x7E00F000))
    
    
    
     
    
    
    
     2 
    
    
    
    
    
    
    
    #define
    
    
    
     MPLL_LOCK (*((volatile unsigned long *)0x7E00F004))
    
    
    
     
    
    
    
     3 
    
    
    
    
    
    
    
    #define
    
    
    
     EPLL_LOCK (*((volatile unsigned long *)0x7E00F008))
    
    
    
     
    
    
    
     4 
    
    
    
    
    
    
    
    #define
    
    
    
     OTHERS (*((volatile unsigned long *)0x7e00f900))
    
    
    
     
    
    
    
     5 
    
    
    
    
    
    
    
    #define
    
    
    
     CLK_DIV0 (*((volatile unsigned long *)0x7E00F020))
    
    
    
     
    
    
    
     6 
    
    
    
    
    
    
    
    #define
    
    
    
     ARM_RATIO 0 /* ARMCLK = DOUTAPLL / (ARM_RATIO + 1) */
    
    
    
     
    
    
    
     7 
    
    
    
    
    
    
    
    #define
    
    
    
     HCLKX2_RATIO 4 /* HCLKX2 = HCLKX2IN / (HCLKX2_RATIO + 1) = 100MHz */
    
    
    
     
    
    
    
     8 
    
    
    
    
    
    
    
    #define
    
    
    
     HCLK_RATIO 0 /* HCLK = HCLKX2 / (HCLK_RATIO + 1) = 100MHz */
    
    
    
     
    
    
    
     9 
    
    
    
    
    
    
    
    #define
    
    
    
     PCLK_RATIO 1 /* PCLK = HCLKX2 / (PCLK_RATIO + 1) = 50MHz */
    
    
    
     
    
    
    
    10 
    
    
    
    
    
    
    
    #define
    
    
    
     MPLL_RATIO 0 /* DOUTMPLL = MOUTMPLL / (MPLL_RATIO + 1) */
    
    
    
     
    
    
    
    11 
    
    
    
     
    
    
    
    12 
    
    
    
    
    
    
    
    #define
    
    
    
     APLL_CON (*((volatile unsigned long *)0x7E00F00C))
    
    
    
     
    
    
    
    13 
    
    
    
    
    
    
    
    #define
    
    
    
     APLL_CON_VAL ((1<<31) | (250 << 16) | (3 << 8) | (1))
    
    
    
     
    
    
    
    14 
    
    
    
    
    
    
    
    #define
    
    
    
     MPLL_CON (*((volatile unsigned long *)0x7E00F010))
    
    
    
     
    
    
    
    15 
    
    
    
    
    
    
    
    #define
    
    
    
     MPLL_CON_VAL ((1<<31) | (250 << 16) | (3 << 8) | (1))
    
    
    
     
    
    
    
    16 
    
    
    
    
    
    
    
    #define
    
    
    
     CLK_SRC (*((volatile unsigned long *)0x7E00F01C))
    
    
    
     
    
    
    
    17 
    
    
    
    
    
    
    
    /*
    
    
    
     ARMCLK = 500MHz, HCLK = 100MHz, PCLK = 50MHZ 
    
    
    
    */
    
    
    
     
    
    
    
    18 
    
    
    
    
    
    
    
    void
    
    
    
     clock_init(
    
    
    
    void
    
    
    
    ) 
    
    
    
    19 
    
    
    
    { 
    
    
    
    20 
    
    
    
     APLL_LOCK 
    
    
    
    =
    
    
    
     
    
    
    
    0xffff
    
    
    
    ; 
    
    
    
    21 
    
    
    
     MPLL_LOCK 
    
    
    
    =
    
    
    
     
    
    
    
    0xffff
    
    
    
    ; 
    
    
    
    22 
    
    
    
     EPLL_LOCK 
    
    
    
    =
    
    
    
     
    
    
    
    0xffff
    
    
    
    ; 
    
    
    
    23 
    
    
    
     
    
    
    
    /*
    
    
    
     set async mode 当CPU时钟 != HCLK时，要设为异步模式 
    
    
    
    */
    
    
    
     
    
    
    
    24 
    
    
    
     OTHERS 
    
    
    
    &=
    
    
    
     
    
    
    
    ~
    
    
    
    0xc0
    
    
    
    ; 
    
    
    
    25 
    
    
    
     
    
    
    
    while
    
    
    
     ((OTHERS 
    
    
    
    &
    
    
    
     
    
    
    
    0xf00
    
    
    
    ) 
    
    
    
    !=
    
    
    
     
    
    
    
    0
    
    
    
    ); 
    
    
    
    26 
    
    
    
     CLK_DIV0 
    
    
    
    =
    
    
    
     (ARM_RATIO) 
    
    
    
    |
    
    
    
     (MPLL_RATIO 
    
    
    
    <<
    
    
    
     
    
    
    
    4
    
    
    
    ) 
    
    
    
    |
    
    
    
     (HCLK_RATIO 
    
    
    
    <<
    
    
    
     
    
    
    
    8
    
    
    
    ) 
    
    
    
    |
    
    
    
     (HCLKX2_RATIO 
    
    
    
    <<
    
    
    
     
    
    
    
    9
    
    
    
    ) 
    
    
    
    |
    
    
    
     (PCLK_RATIO 
    
    
    
    <<
    
    
    
     
    
    
    
    12
    
    
    
    ); 
    
    
    
    27 
    
    
    
     APLL_CON 
    
    
    
    =
    
    
    
     APLL_CON_VAL; 
    
    
    
    /*
    
    
    
     500MHz 
    
    
    
    */
    
    
    
     
    
    
    
    28 
    
    
    
     MPLL_CON 
    
    
    
    =
    
    
    
     MPLL_CON_VAL; 
    
    
    
    /*
    
    
    
     500MHz 
    
    
    
    */
    
    
    
     
    
    
    
    29 
    
    
    
     CLK_SRC 
    
    
    
    =
    
    
    
     
    
    
    
    0x03
    
    
    
    ; 
    
    
    
    30 
    
    
    
    }
   
   
   
   

uart.h

   
   
   
   

    
    
    
    
    1 
    
    
    
    #ifndef __UART_H__ 
    
    
    
    2 
    
    
    
    
    
    
    
    #define
    
    
    
     __UART_H__
    
    
    
     
    
    
    
    3 
    
    
    
     
    
    
    
    4 
    
    
    
    
    
    
    
    void
    
    
    
     myputchar(
    
    
    
    char
    
    
    
     c); 
    
    
    
    5 
    
    
    
    
    
    
    
    char
    
    
    
     mygetchar(
    
    
    
    void
    
    
    
    ); 
    
    
    
    6 
    
    
    
    
    
    
    
    void
    
    
    
     init_uart(
    
    
    
    void
    
    
    
    ); 
    
    
    
    7 
    
    
    
     
    
    
    
    8 
    
    
    
    
    
    
    
    #endif
   
   
   
   

uart.c

   
   
   
   

    
    
    
    
     1 
    
    
    
    #define
    
    
    
     ULCON0 (*((volatile unsigned long *)0x7F005000))
    
    
    
     
    
    
    
     2 
    
    
    
    
    
    
    
    #define
    
    
    
     UCON0 (*((volatile unsigned long *)0x7F005004))
    
    
    
     
    
    
    
     3 
    
    
    
    
    
    
    
    #define
    
    
    
     UFCON0 (*((volatile unsigned long *)0x7F005008))
    
    
    
     
    
    
    
     4 
    
    
    
    
    
    
    
    #define
    
    
    
     UMCON0 (*((volatile unsigned long *)0x7F00500C))
    
    
    
     
    
    
    
     5 
    
    
    
    
    
    
    
    #define
    
    
    
     UTRSTAT0 (*((volatile unsigned long *)0x7F005010))
    
    
    
     
    
    
    
     6 
    
    
    
    
    
    
    
    #define
    
    
    
     UFSTAT0 (*((volatile unsigned long *)0x7F005018))
    
    
    
     
    
    
    
     7 
    
    
    
    
    
    
    
    #define
    
    
    
     UTXH0 (*((volatile unsigned char *)0x7F005020))
    
    
    
     
    
    
    
     8 
    
    
    
    
    
    
    
    #define
    
    
    
     URXH0 (*((volatile unsigned char *)0x7F005024))
    
    
    
     
    
    
    
     9 
    
    
    
    
    
    
    
    #define
    
    
    
     UBRDIV0 (*((volatile unsigned short *)0x7F005028))
    
    
    
     
    
    
    
    10 
    
    
    
    
    
    
    
    #define
    
    
    
     UDIVSLOT0 (*((volatile unsigned short *)0x7F00502C))
    
    
    
     
    
    
    
    11 
    
    
    
     
    
    
    
    12 
    
    
    
    
    
    
    
    #define
    
    
    
     GPACON (*((volatile unsigned long *)0x7F008000))
    
    
    
     
    
    
    
    13 
    
    
    
     
    
    
    
    14 
    
    
    
    
    
    
    
    void
    
    
    
     init_uart(
    
    
    
    void
    
    
    
    ) 
    
    
    
    15 
    
    
    
    { 
    
    
    
    16 
    
    
    
     GPACON 
    
    
    
    &=
    
    
    
     
    
    
    
    ~
    
    
    
    0xff
    
    
    
    ; 
    
    
    
    17 
    
    
    
     GPACON 
    
    
    
    |=
    
    
    
     
    
    
    
    0x22
    
    
    
    ; 
    
    
    
    18 
    
    
    
     
    
    
    
    /*
    
    
    
     ULCON0 
    
    
    
    */
    
    
    
     
    
    
    
    19 
    
    
    
     ULCON0 
    
    
    
    =
    
    
    
     
    
    
    
    0x3
    
    
    
    ; 
    
    
    
    /*
    
    
    
     数据位:8, 无较验, 停止位: 1, 8n1 
    
    
    
    */
    
    
    
     
    
    
    
    20 
    
    
    
     UCON0 
    
    
    
    =
    
    
    
     
    
    
    
    0x5
    
    
    
    ; 
    
    
    
    /*
    
    
    
     使能UART发送、接收 
    
    
    
    */
    
    
    
     
    
    
    
    21 
    
    
    
     UFCON0 
    
    
    
    =
    
    
    
     
    
    
    
    0x01
    
    
    
    ; 
    
    
    
    /*
    
    
    
     FIFO ENABLE 
    
    
    
    */
    
    
    
     
    
    
    
    22 
    
    
    
     UMCON0 
    
    
    
    =
    
    
    
     
    
    
    
    0
    
    
    
    ; 
    
    
    
    23 
    
    
    
     
    
    
    
    24 
    
    
    
     
    
    
    
    /*
    
    
    
     波特率 
    
    
    
    */
    
    
    
     
    
    
    
    25 
    
    
    
     
    
    
    
    /*
    
    
    
     DIV_VAL = (PCLK / (bps x 16 ) ) - 1 
    
    
    
    26 
    
    
    
     * bps = 115200 
    
    
    
    27 
    
    
    
     * DIV_VAL = (50000000 / (115200 x 16 ) ) - 1 
    
    
    
    28 
    
    
    
     * = 26.13 
    
    
    
    29 
    
    
    
     
    
    
    
    */
    
    
    
     
    
    
    
    30 
    
    
    
     UBRDIV0 
    
    
    
    =
    
    
    
     
    
    
    
    26
    
    
    
    ; 
    
    
    
    31 
    
    
    
     
    
    
    
    /*
    
    
    
     x/16 = 0.13 
    
    
    
    32 
    
    
    
     * x = 2 （到S3C6410手册上查对应2应该赋什么值） 
    
    
    
    33 
    
    
    
     
    
    
    
    */
    
    
    
     
    
    
    
    34 
    
    
    
     UDIVSLOT0 
    
    
    
    =
    
    
    
     
    
    
    
    0x0808
    
    
    
    ; 
    
    
    
    35 
    
    
    
    } 
    
    
    
    36 
    
    
    
     
    
    
    
    37 
    
    
    
    
    
    
    
    char
    
    
    
     mygetchar(
    
    
    
    void
    
    
    
    ) 
    
    
    
    38 
    
    
    
    { 
    
    
    
    39 
    
    
    
     
    
    
    
    while
    
    
    
     (
    
    
    
    !
    
    
    
    (UFSTAT0 
    
    
    
    &
    
    
    
     
    
    
    
    0x7f
    
    
    
    )); 
    
    
    
    40 
    
    
    
     
    
    
    
    return
    
    
    
     URXH0; 
    
    
    
    41 
    
    
    
    } 
    
    
    
    42 
    
    
    
     
    
    
    
    43 
    
    
    
    
    
    
    
    void
    
    
    
     myputchar(
    
    
    
    char
    
    
    
     c) 
    
    
    
    44 
    
    
    
    { 
    
    
    
    45 
    
    
    
     
    
    
    
    while
    
    
    
     (UFSTAT0 
    
    
    
    &
    
    
    
     (
    
    
    
    1
    
    
    
    <<
    
    
    
    14
    
    
    
    )); 
    
    
    
    46 
    
    
    
     UTXH0 
    
    
    
    =
    
    
    
     c; 
    
    
    
    47 
    
    
    
    } 
    
    
    
    48 
    
    
    
    
   
   
   
   

main.c

   
   
   
   

    
    
    
    
     1 
    
    
    
    #include 
    
    
    
    "
    
    
    
    uart.h
    
    
    
    "
    
    
    
     
    
    
    
     2 
    
    
    
    
    
    
    
    int
    
    
    
     main() 
    
    
    
     3 
    
    
    
    { 
    
    
    
     4 
    
    
    
     
    
    
    
    char
    
    
    
     c; 
    
    
    
     5 
    
    
    
     init_uart(); 
    
    
    
     6 
    
    
    
     
    
    
    
    while
    
    
    
     (
    
    
    
    1
    
    
    
    ) 
    
    
    
     7 
    
    
    
     { 
    
    
    
     8 
    
    
    
     c 
    
    
    
    =
    
    
    
     mygetchar(); 
    
    
    
     9 
    
    
    
     myputchar(c
    
    
    
    +
    
    
    
    1
    
    
    
    ); 
    
    
    
    10 
    
    
    
     } 
    
    
    
    11 
    
    
    
     
    
    
    
    return
    
    
    
     
    
    
    
    0
    
    
    
    ; 
    
    
    
    12 
    
    
    
    }
   
   
   
   

Makefile

   
   
   
   

    
    
    
    
     1 
    
    
    
    uart.
    
    
    
    bin:
    
    
    
     start.o main.o uart.o clock.o 
    
    
    
     2 
    
    
    
     arm-linux-ld -Ttext 
    
    
    
    0
    
    
    
     -o uart.elf $^ 
    
    
    
     3 
    
    
    
     arm-linux-objcopy -O binary uart.elf uart.bin 
    
    
    
     4 
    
    
    
     arm-linux-objdump -D uart.elf > uart.dis 
    
    
    
     5 
    
    
    
     
    
    
    
     6 
    
    
    
    %.o : %.S 
    
    
    
     7 
    
    
    
     arm-linux-gcc -o $@ $< -c 
    
    
    
     8 
    
    
    
     
    
    
    
     9 
    
    
    
    %.o : %.c 
    
    
    
    10 
    
    
    
     arm-linux-gcc -o $@ $< -c 
    
    
    
    11 
    
    
    
     
    
    
    
    12 
    
    
    
    
    
    
    
    clean:
    
    
    
     
    
    
    
    13 
    
    
    
     rm *.o uart.elf uart.bin uart.dis