readromidtask.c

DS2480芯片是实现1-wire协议的芯片。本驱动使用C8051F206单片机与DS2480芯片进行交互

//-----------------------------------------------------------------------------
// ReadROMIDTask.c
//-----------------------------------------------------------------------------
// 版权所有 2008 黄晓斌, 空军雷达学院.
// http://blog.xiaobing.org
//
// 文件描述: 读取iButton的8字节ID号
//
//-----------------------------------------------------------------------------


//-----------------------------------------------------------------------------
// 头文件调用
//-----------------------------------------------------------------------------
#include <C8051F200.h>                 // SFR declarations
#include "Data.h"
#include "DS2480B.h"
//-----------------------------------------------------------------------------


//-----------------------------------------------------------------------------
// 函数原型申明
//-----------------------------------------------------------------------------
extern void ChangeState(unsigned char, unsigned char);
extern void WriteData(char *, unsigned int);
extern char ReadData(char *, unsigned int, unsigned int);
extern void Wakeup(unsigned char);
extern void DelayMS(unsigned int);
extern void ResetReceBuf(void);
unsigned int DoCRC8(unsigned char *, unsigned char, unsigned char);
//-----------------------------------------------------------------------------


//-----------------------------------------------------------------------------
// CRC表定义
//-----------------------------------------------------------------------------
static unsigned char dscrc_table[] = {
        0, 94,188,226, 97, 63,221,131,194,156,126, 32,163,253, 31, 65,
      157,195, 33,127,252,162, 64, 30, 95,  1,227,189, 62, 96,130,220,
       35,125,159,193, 66, 28,254,160,225,191, 93,  3,128,222, 60, 98,
      190,224,  2, 92,223,129, 99, 61,124, 34,192,158, 29, 67,161,255,
       70, 24,250,164, 39,121,155,197,132,218, 56,102,229,187, 89,  7,
      219,133,103, 57,186,228,  6, 88, 25, 71,165,251,120, 38,196,154,
      101, 59,217,135,  4, 90,184,230,167,249, 27, 69,198,152,122, 36,
      248,166, 68, 26,153,199, 37,123, 58,100,134,216, 91,  5,231,185,
      140,210, 48,110,237,179, 81, 15, 78, 16,242,172, 47,113,147,205,
       17, 79,173,243,112, 46,204,146,211,141,111, 49,178,236, 14, 80,
      175,241, 19, 77,206,144,114, 44,109, 51,209,143, 12, 82,176,238,
       50,108,142,208, 83, 13,239,177,240,174, 76, 18,145,207, 45,115,
      202,148,118, 40,171,245, 23, 73,  8, 86,180,234,105, 55,213,139,
       87,  9,235,181, 54,104,138,212,149,203, 41,119,244,170, 72, 22,
      233,183, 85, 11,136,214, 52,106, 43,117,151,201, 74, 20,246,168,
      116, 42,200,150, 21, 75,169,247,182,232, 10, 84,215,137,107, 53};	 	
//-----------------------------------------------------------------------------
// 其它变量定义
//-----------------------------------------------------------------------------
unsigned char ROM_ID[8] = {0};
//-----------------------------------------------------------------------------


void ReadROMIDTask(void) 
{	
	unsigned char buf[8] = {0};
	unsigned char pos;

	ChangeState(READROMIDTASK, RUNNING);

	//Step 1. 设置DS2480S为数据模式(发送0xE1)，并发送Read ROM Command(发送0x33)
	pos = 0; 
	buf[pos++] = 0xE1;
	buf[pos++] = 0x33;
	ResetReceBuf();
	WriteData(buf, pos);
	
	//Step 2. 读取Read ROM Command命令的响应码0x33 		
	if ( !ReadData(buf, 1, READTIMEOUT_PER_BYTE) || (buf[0] != 0x33) )
		goto FINALLY;			
	
	//Step 3. Read ROM ID (8 bytes) 发送 0xFF (x8)
	for (pos = 0; pos < 8; pos++) buf[pos] = 0xFF;
	ResetReceBuf();
	WriteData(buf, pos);

	//Step 4. Read ROM ID 响应 8字节 		
	if ( !ReadData(buf, 8, 8*READTIMEOUT_PER_BYTE) )
		goto FINALLY;			
	
	//Step 5. CRC效验		
	for (pos = 0; pos < 8; pos++) 
		ROM_ID[pos] = buf[pos];
			
	if (DoCRC8(ROM_ID, 8, 0) == 0) Wakeup(SENDROMIDTASK); // 效验成功，唤醒发送ID任务	
	
FINALLY:				
	//Step 6. 设置为命令模式并复位
	DelayMS(2);
	pos = 0; 
	buf[pos++] = 0xE3;
	//buf[pos++] = 0xC1;
	//buf[pos++] = 0xC1;
	//ResetReceBuf();
	WriteData(buf, pos);							

	ChangeState(READROMIDTASK, SLEEPING);  	
}

unsigned int DoCRC8(unsigned char *buf, unsigned char len, unsigned char seed)
{
	unsigned char crc = seed;

	while (len--)             
	{ 
		crc = dscrc_table[crc ^ *(buf++)];             
	}             	
	return crc;
}