ARM7 USB转485例子

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本帖最后由 eehome 于 2013-1-5 10:01 编辑

/******************************************************************
  Copyright (C), 2008-2009, 力天电子，Litian Tech.Co.Ltd.
  Module Name : u***_RS485
  File Name    : u***_RS485.c
  Author : YE HONGYU
  Create Date : 2010/05/30
  Version : 1.0
  Function    : RS485实验
  Description : 无
  Support    : www.LT430.com
******************************************************************/
#include
#include

//系统时钟宏定义
#define XTALFREQ 12000000       //XTAL frequency in Hz
#define PCLKFREQ (XTALFREQ/4)    //pclk must always be XTALFREQ/4?
//函数宏定义
#define SetBit(x,y);    ( (x) |= (1< #define ClrBit(x,y);    ( (x) &= (~(1< //函数声明
void sendByte(char byte);
void delayn(unsigned long n);
void sendStr(char *Str);
//主函数
int main(void)
{
  //配置连接UART1的IO口
  /*Configure the pins that are connected to RX and TX on UART1 */
  PINSEL0_bit.P0_8 = 1;PINSEL0_bit.P0_9 = 1;

  //配置UART1的寄存器
  /*Configure UART1 to 9600 buad, 8 bit, 1 stop, no parity */
  U1FCR = 1;             // Enable FIFOs whether used or not
  SetBit(U1LCR,7);       // U1LCR = 0X80-enable access to divisor
                        // latch bit, necessary for setting baud rate
  U1LCR |= 3;             // Eight bits U1LCR = 0X83
  ClrBit(U1LCR,3);       // No parity
  ClrBit(U1LCR,2);       // One stop bit
  U1DLL = PCLKFREQ / (9600 * 16);
  U1DLM = (PCLKFREQ / (9600 * 16)) >> 8;
  ClrBit(U1LCR,7);       // Disable access to divisor latch

sendStr("LT_ARM214X RS485 test start.. n");
delayn(100000);
sendStr("LT_ARM214X RS485 test over! n");
while(1);

}

//发送字符串
void sendStr(char *Str)
{
  while((*Str)!='')
  {
sendByte(*Str);
Str++;
  }
}
//发送单个字符
void sendByte(char byte)
{
while (!(U1LSR &0x20)); //U1THR THRE bit set when U1THR contains valid data
U1THR = byte;
}
//延时函数
void delayn(unsigned long n)
{
  while(n--);
}