• uarts裸机程序


    硬件平台:JZ2440

    实现功能:向串口软件实现输出putchar函数

    start.s   --> 设置堆栈,关闭看门狗,初始化时钟,初始化sdram

    init.c      -->初始化函数

    uart.c    -->初始化串口寄存器

    uart.h    -->

    main.c  -->

    start.s源码:

    .extern main
    .text
    .global _start
    _start:
          ldr sp,=4096
          bl  watchdog_init
          bl  clock_init
          bl  sdram_init 
          bl  copy_steppingstone_to_sdram
          ldr pc,=sdram
    sdram:
          ldr sp,=0x34000000
          ldr lr,=main_return
          ldr pc,=main    
    main_return:
          b main_return
          
          
          
          
          
          
          
          

    init.c 源码:

    //watchdog
    #define WTCON      (*(volatile unsigned long *)0x53000000)
    
    //clock 
    #define LOCKTIME   (*(volatile unsigned long *)0x4c000000)
    #define MPLLCON    (*(volatile unsigned long *)0x4c000004)
    #define CLKDIVN    (*(volatile unsigned long *)0x4c000014)
    
    //sdram 
    #define BWSCON     (*(volatile unsigned long *)0x48000000)
    #define BANKCON0   (*(volatile unsigned long *)0x48000004)
    #define BANKCON1   (*(volatile unsigned long *)0x48000008)
    #define BANKCON2   (*(volatile unsigned long *)0x4800000c)
    #define BANKCON3   (*(volatile unsigned long *)0x48000010)
    #define BANKCON4   (*(volatile unsigned long *)0x48000014)
    #define BANKCON5   (*(volatile unsigned long *)0x48000018)
    #define BANKCON6   (*(volatile unsigned long *)0x4800001c)
    #define BANKCON7   (*(volatile unsigned long *)0x48000020)
    #define REFRESH    (*(volatile unsigned long *)0x48000024)
    #define BANKSIZE   (*(volatile unsigned long *)0x48000028)
    #define MRSRB6     (*(volatile unsigned long *)0x4800002c)
    #define MRSRB7     (*(volatile unsigned long *)0x48000030)
    
    void watchdog_init(void)
    {
        WTCON=0;
    }
    
    
    void clock_init(void)
    {
        CLKDIVN=0x03;    
        __asm__
        (
        "mrc p15,0,r1,c1,c0,0
    "
        "orr r1,r1,#0xc0000000
    "
        "mcr p15,0,r1,c1,c0,0
    "
        );
           MPLLCON=((0x5c<<12)|(0x01<<4)|(0x02));
    }
    
    void sdram_init(void)
    {
        volatile unsigned long *sdram_base=(volatile unsigned long *)0x48000000;
        sdram_base[0]  = 0x22011110;     
        sdram_base[1]  = 0x00000700;    
        sdram_base[2]  = 0x00000700;    
        sdram_base[3]  = 0x00000700;   
        sdram_base[4]  = 0x00000700;    
        sdram_base[5]  = 0x00000700;    
        sdram_base[6]  = 0x00000700;    
        sdram_base[7]  = 0x00018005;    
        sdram_base[8]  = 0x00018005;    
        sdram_base[9]  = 0x008C04F4;
        sdram_base[10] = 0x000000B1;    
        sdram_base[11] = 0x00000030;    
        sdram_base[12] = 0x00000030;     
        
    }
    
    void copy_steppingstone_to_sdram(void)
    {
        unsigned int *sour=(unsigned int *)0x00000000;
        unsigned int *dest=(unsigned int *)0x30000000;
        
        while(sour<=(unsigned int *)4096)
        {
            *dest++=*sour++;        
        }
    }

    uart.c 源码:

    //uart 
    #define  ULCON0      (*(volatile unsigned long *)0x50000000)
    #define  UCON0       (*(volatile unsigned long *)0x50000004)
    #define UFCON0       (*(volatile unsigned long *)0x50000008)
    #define UMCON0       (*(volatile unsigned long *)0x5000000c)
    #define  UTRSTAT0    (*(volatile unsigned long *)0x50000010)
    #define  UERSTAT0    (*(volatile unsigned long *)0x50000014)
    #define  UTXH0       (*(volatile unsigned char *)0x50000020)
    #define  URXH0       (*(volatile unsigned char *)0x50000024)
    #define  UBRDIV0     (*(volatile unsigned long *)0x50000028)
    
    //GPH
    #define  GPHCON      (*(volatile unsigned long *)0x56000070)
    #define  GPHDAT      (*(volatile unsigned long *)0x56000074)
    #define  GPHUP       (*(volatile unsigned long *)0x56000078)
    
    
    void uart0_init(void)
    {
        GPHCON|=0xa0;
        GPHUP=0x0c;
        
        ULCON0=0x03;    
        UCON0=0x05;
        UFCON0=0x00;     
        UMCON0=0x00;     
        UBRDIV0=((50000000/(115200*16))-1);    
    }
    
    unsigned char getc(void)
    {
        while(!(UTRSTAT0 & 0x01));
        return URXH0;
    }
    
    
    void putc(unsigned char date)
    {
        while(!(UTRSTAT0 & 0x02));
        UTXH0=date;
    }

    uart.h 源码:

    #ifndef _UART_H_ 
    #define _UART_H_ 
    
    void uart0_init(void);
    unsigned char getc(void);
    void putc(unsigned char date);
    
    
    
    #endif

    main.c 源码:

    #include"uart.h"
    
    int main(void)
    {
        uart0_init();
        while(1)
        putc(getc()+1);    
        return 0;
    }

    连接脚本uart.lds :

    SECTIONS
    {
      . = 0x30000000;
      .text  : {*(.test)}
      .rodata : {*(.rodata)}
      .dtat  : {*(.data)}
      .bss   : {*(.bss) *(COMMON)}
    
    }

    Makefile:

    objs:= start.o init.o uart.o main.o 
    
    uart.bin:$(objs)
        arm-linux-ld -Tuart.lds -o uart_elf $^
        arm-linux-objcopy -O binary -S uart_elf $@
        arm-linux-objdump -D -m arm uart_elf > uart.dis
        
    %.o:%.s
        arm-linux-gcc  -o $@ -c $<
    
    %.o:%.c
        arm-linux-gcc  -o $@ -c $<
    
    clean:
        rm -f *.o *.bin *.dis uart_elf
        
        
        
        
        
        
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  • 原文地址:https://www.cnblogs.com/zsy12138/p/10408289.html
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