boot.c

本人写的用与mega128单片机

/***************************************************** 
采用串行接口实现Boot_load应用的实例 
华东师大电子系 马 潮 2004.07 
Compiler:    ICC-AVR 6.31 
Target:    Mega128 
Crystal:    16Mhz 
Used:        T/C0,USART0 
*****************************************************/ 
#include <iom128v.h> 
#define SPM_PAGESIZE 256              file://M128的一个Flash页为256字节(128字) 
#define BAUD 38400                file://波特率采用38400bps 
#define CRYSTAL 16000000            file://系统时钟16MHz 
file://计算和定义M128的波特率设置参数 
#define BAUD_SETTING (unsigned char)((unsigned long)CRYSTAL/(16*(unsigned long)BAUD)-1) 
#define BAUD_H (unsigned char)(BAUD_SETTING>>8) 
#define BAUD_L (unsigned char)BAUD_SETTING 

#define DATA_BUFFER_SIZE SPM_PAGESIZE        file://定义接收缓冲区长度 
file://定义Xmoden控制字符 
#define XMODEM_NUL 0x00 
#define XMODEM_SOH 0x01 
#define XMODEM_STX 0x02 
#define XMODEM_EOT 0x04 
#define XMODEM_ACK 0x06 
#define XMODEM_NAK 0x15 
#define XMODEM_CAN 0x18 
#define XMODEM_EOF 0x1A 
#define XMODEM_RECIEVING_WAIT_CHAR 'C' 
file://定义全局变量 
const char startupString[]="Type 'd' download, Others run app.\n\r\0"; 
char data[DATA_BUFFER_SIZE]; 
long address = 0; 
file://擦除(code=0x03)和写入(code=0x05)一个Flash页 
void boot_page_ew(long p_address,char code) 
{ 
    asm("mov r30,r16\n" 
        "mov r31,r17\n" 
        "out 0x3b,r18\n");            file://将页地址放入Z寄存器和RAMPZ的Bit0中 
    SPMCSR = code;                file://寄存器SPMCSR中为操作码 
    asm("spm\n");                    file://对指定Flash页进行操作 
}         
file://填充Flash缓冲页中的一个字 
void boot_page_fill(unsigned int address,int data) 
{ 
    asm("mov r30,r16\n" 
        "mov r31,r17\n"             file://Z寄存器中为填冲页内地址 
        "mov r0,r18\n" 
        "mov r1,r19\n");            file://R0R1中为一个指令字 
    SPMCSR = 0x01; 
    asm("spm\n"); 
} 
file://等待一个Flash页的写完成 
void wait_page_rw_ok(void) 
{ 
      while(SPMCSR & 0x40) 
     { 
         while(SPMCSR & 0x01); 
         SPMCSR = 0x11; 
         asm("spm\n"); 
     } 
} 
file://更新一个Flash页的完整处理 
void write_one_page(void) 
{ 
    int i; 
    boot_page_ew(address,0x03);                    file://擦除一个Flash页 
    wait_page_rw_ok();                            file://等待擦除完成 
    for(i=0;i<SPM_PAGESIZE;i+=2)                file://将数据填入Flash缓冲页中 
    { 
        boot_page_fill(i, data[i]+(data[i+1]<<8)); 
    } 
    boot_page_ew(address,0x05);                    file://将缓冲页数据写入一个Flash页 
    wait_page_rw_ok();                            file://等待写入完成 
}         
file://从RS232发送一个字节 
void uart_putchar(char c) 
{ 
    while(!(UCSR0A & 0x20)); 
    UDR0 = c; 
} 
file://从RS232接收一个字节 
int uart_getchar(void) 
{ 
    unsigned char status,res; 
    if(!(UCSR0A & 0x80)) return -1;        file://no data to be received 
    status = UCSR0A; 
    res = UDR0; 
    if (status & 0x1c) return -1;        // If error, return -1 
    return res; 
} 
file://等待从RS232接收一个有效的字节 
char uart_waitchar(void) 
{ 
    int c; 
    while((c=uart_getchar())==-1); 
    return (char)c; 
} 
file://计算CRC 
int calcrc(char *ptr, int count) 
{ 
    int crc = 0; 
    char i; 
     
    while (--count >= 0) 
    { 
        crc = crc ^ (int) *ptr++ << 8; 
        i = 8; 
        do 
        { 
        if (crc & 0x8000) 
            crc = crc << 1 ^ 0x1021; 
        else 
            crc = crc << 1; 
        } while(--i); 
    } 
    return (crc); 
} 
file://退出Bootloader程序，从0x0000处执行应用程序 
void quit(void) 
{ 
      uart_putchar('O');uart_putchar('K'); 
uart_putchar(0x0d);uart_putchar(0x0a); 
     while(!(UCSR0A & 0x20));            file://等待结束提示信息回送完成 
  MCUCR = 0x01; 
     MCUCR = 0x00;                    file://将中断向量表迁移到应用程序区头部 
     RAMPZ = 0x00;                    file://RAMPZ清零初始化 
     asm("jmp 0x0000\n");                file://跳转到Flash的0x0000处，执行用户的应用程序 
} 
file://主程序 
void main(void) 
{ 
    int i = 0; 
    unsigned char timercount = 0; 
    unsigned char packNO = 1; 
    int bufferPoint = 0; 
    unsigned int crc; 
file://初始化M128的USART0 
    UBRR0H = BAUD_H;     
    UBRR0L = BAUD_L;            file://Set baud rate 
    UCSR0B = 0x18;            file://Enable Receiver and Transmitter 
    UCSR0C = 0x0E;            file://Set frame format: 8data, 2stop bit 
file://初始化M128的T/C0，15ms自动重载 
  OCR0 = 0xEA; 
  TCCR0 = 0x0F;     
file://向PC机发送开始提示信息 
    while(startupString[i]!='\0') 
    { 
        uart_putchar(startupString[i]); 
        i++; 
    } 
file://3秒种等待PC下发"d"，否则退出Bootloader程序，从0x0000处执行应用程序 
    while(1) 
    { 
        if(uart_getchar()== 'd') break; 
        if (TIFR & 0x02)                        file://timer0 over flow 
        { 
               if (++timercount > 200) quit();        file://200*15ms = 3s 
            TIFR = TIFR|0x02; 
        } 
    } 
    file://每秒向PC机发送一个控制字符"C"，等待控制字〈soh〉 
    while(uart_getchar()!=XMODEM_SOH)        file://receive the start of Xmodem 
    { 
         if(TIFR & 0x02)                    file://timer0 over flow 
        { 
            if(++timercount > 67)                        file://wait about 1 second 
            { 
                uart_putchar(XMODEM_RECIEVING_WAIT_CHAR);    file://send a "C" 
                timercount=0; 
            } 
            TIFR=TIFR | 0x02; 
        } 
    } 
    file://开始接收数据块 
    do 
    { 
        if ((packNO == uart_waitchar()) && (packNO ==(~uart_waitchar()))) 
        {    file://核对数据块编号正确 
            for(i=0;i<128;i++)                file://接收128个字节数据 
            { 
                data[bufferPoint]= uart_waitchar(); 
                bufferPoint++;     
            } 
            crc = (uart_waitchar()<<8); 
            crc += uart_waitchar();            file://接收2个字节的CRC效验字 
            if(calcrc(&data[bufferPoint-128],128)==crc)    file://CRC校验验证 
            {    file://正确接收128个字节数据 
                while(bufferPoint >= SPM_PAGESIZE) 
                {    file://正确接受256个字节的数据 
                    write_one_page();            file://收到256字节写入一页Flash中 
                    address += SPM_PAGESIZE;    file://Flash页加1 
                    bufferPoint = 0; 
                }     
                uart_putchar(XMODEM_ACK);        file://正确收到一个数据块 
                packNO++;                        file://数据块编号加1 
            } 
            else 
            { 
                uart_putchar(XMODEM_NAK);        file://要求重发数据块 
            } 
        } 
        else 
        { 
            uart_putchar(XMODEM_NAK);                file://要求重发数据块 
        } 
    }while(uart_waitchar()!=XMODEM_EOT);                file://循环接收，直到全部发完 
    uart_putchar(XMODEM_ACK);                        file://通知PC机全部收到 
     
    if(bufferPoint) write_one_page();                file://把剩余的数据写入Flash中 
    quit();                file://退出Bootloader程序，从0x0000处执行应用程序 
}