51單片機RS485通信與Modbus協議 - ELEOK

#include <reg52.h>
struct sTime { //日期時間結構體定義
unsigned int year;
unsigned char mon;
unsigned char day;
unsigned char hour;
unsigned char min;
unsigned char sec;
unsigned char week;
};
bit flag200ms = 1; //200ms定時標志
bit reqRefresh = 0; //時間刷新請求
struct sTime bufTime; //日期時間緩沖區
unsigned char T0RH = 0; //T0重載值的高字節
unsigned char T0RL = 0; //T0重載值的低字節
void ConfigTimer0(unsigned int ms);
void RefreshTimeShow();
extern void InitDS1302();
extern void GetRealTime(struct sTime *time);
extern void SetRealTime(struct sTime *time);
extern void UartDriver();
extern void ConfigUART(unsigned int baud);
extern void UartRxMonitor(unsigned char ms);
extern void UartWrite(unsigned char *buf, unsigned char len);
extern unsigned int GetCRC16(unsigned char *ptr, unsigned char len);
extern void InitLcd1602();
extern void LcdShowStr(unsigned char x, unsigned char y, unsigned char *str);
void main()
{
unsigned char psec=0xAA; //秒備份，初值AA確保首次讀取時間后會刷新顯示
EA = 1; //開總中斷
ConfigTimer0(1); //配置T0定時1ms
ConfigUART(9600); //配置波特率為9600
InitDS1302(); //初始化實時時鐘
InitLcd1602(); //初始化液晶
//初始化屏幕上固定不變的內容
LcdShowStr(3, 0, "20 - - ");
LcdShowStr(4, 1, " : : ");
while (1)
{
UartDriver(); //調用串口驅動
if (flag200ms)
{
flag200ms = 0;
GetRealTime(&bufTime); //獲取當前時間
if (reqRefresh || (psec!=bufTime.sec))
{ //檢測到時間刷新請求或時間有變化時刷新顯示
RefreshTimeShow();
psec = bufTime.sec; //用當前值更新上次秒數
}
}
}
}
/* 將一個BCD碼字節顯示到屏幕上，(x,y)-屏幕起始坐標，bcd-待顯示BCD碼 */
void ShowBcdByte(unsigned char x, unsigned char y, unsigned char bcd)
{
unsigned char str[4];
str[0] = (bcd >> 4) + '0';
str[1] = (bcd&0x0F) + '0';
str[2] = '\0';
LcdShowStr(x, y, str);
}
/* 刷新日期時間的顯示 */
void RefreshTimeShow()
{
ShowBcdByte(5, 0, bufTime.year);
ShowBcdByte(8, 0, bufTime.mon);
ShowBcdByte(11, 0, bufTime.day);
ShowBcdByte(4, 1, bufTime.hour);
ShowBcdByte(7, 1, bufTime.min);
ShowBcdByte(10, 1, bufTime.sec);
}
/* 串口動作函數，根據接收到的命令幀執行響應的動作
buf-接收到的命令幀指針，len-命令幀長度 */
void UartAction(unsigned char *buf, unsigned char len)
{
unsigned int crc;
unsigned char crch, crcl;
if (buf[0] != 0x01) //本例中的本機地址設定為0x01，
{ //如數據幀中的地址字節與本機地址不符，
return; //則直接退出，即丟棄本幀數據不做任何處理
}
//地址相符時，再對本幀數據進行校驗
crc = GetCRC16(buf, len-2); //計算CRC校驗值
crch = crc >> 8;
crcl = crc & 0xFF;
if ((buf[len-2]!=crch) || (buf[len-1]!=crcl))
{
return; //如CRC校驗不符時直接退出
}
//地址和校驗字均相符后，解析功能碼，執行相關操作
switch (buf[1])
{
case 0x06: //寫入單個寄存器
if ((buf[2]==0x00) && (buf[3]<=0x06)) //地址0x0000～0x0006分別對應
{ // “年/月/日/時/分/秒/星期”
GetRealTime(&bufTime); //獲取當前時間
switch (buf[3]) //由寄存器地址決定要修改的時間位
{
case 0: bufTime.year = 0x2000 + buf[5]; break;
case 1: bufTime.mon = buf[5]; break;
case 2: bufTime.day = buf[5]; break;
case 3: bufTime.hour = buf[5]; break;
case 4: bufTime.min = buf[5]; break;
case 5: bufTime.sec = buf[5]; break;
case 6: bufTime.week = buf[5]; break;
default: break;
}
SetRealTime(&bufTime); //寫入新修改后的時間
reqRefresh = 1; //設置顯示刷新請求
len -= 2; //長度-2以重新計算CRC并返回原幀
break;
}
else //寄存器地址不被支持時，返回錯誤碼
{
buf[1] = 0x86; //功能碼最高位置1
buf[2] = 0x02; //設置異常碼為02-無效地址
len = 3;
break;
}
default: //其它不支持的功能碼
buf[1] |= 0x80; //功能碼最高位置1
buf[2] = 0x01; //設置異常碼為01-無效功能
len = 3;
break;
}
crc = GetCRC16(buf, len); //計算返回幀的CRC校驗值
buf[len++] = crc >> 8; //CRC高字節
buf[len++] = crc & 0xFF; //CRC低字節
UartWrite(buf, len); //發送返回幀
}
/* 配置并啟動T0，ms-T0定時時間 */
void ConfigTimer0(unsigned int ms)
{
unsigned long tmp; //臨時變量
tmp = 11059200 / 12; //定時器計數頻率
tmp = (tmp * ms) / 1000; //計算所需的計數值
tmp = 65536 - tmp; //計算定時器重載值
tmp = tmp + 33; //補償中斷響應延時造成的誤差
T0RH = (unsigned char)(tmp>>8); //定時器重載值拆分為高低字節
T0RL = (unsigned char)tmp;
TMOD &= 0xF0; //清零T0的控制位
TMOD |= 0x01; //配置T0為模式1
TH0 = T0RH; //加載T0重載值
TL0 = T0RL;
ET0 = 1; //使能T0中斷
TR0 = 1; //啟動T0
}
/* T0中斷服務函數，執行按鍵掃描和200ms定時 */
void InterruptTimer0() interrupt 1
{
static unsigned char tmr200ms = 0;
TH0 = T0RH; //重新加載重載值
TL0 = T0RL;
UartRxMonitor(1); //串口接收監控
tmr200ms++;
if (tmr200ms >= 200) //定時200ms
{
tmr200ms = 0;
flag200ms = 1;
}
}

復制代碼

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