AT89C52就是個常用的8位單片機，低電壓還高性能，用的是CMOS工藝。片子里有8KB的Flash程序存儲器，能擦寫上千次，還有256字節的RAM。這玩意是ATMEL家出的，技術靠譜，和標準的MCS-51指令集兼容，內部有個8位CPU加Flash存儲，所以在電子圈里應用挺廣的。
主要特點也簡單：
1. 兼容MCS-51指令系統
2. 8KB可反復擦寫Flash（能寫1000次以上）
3. 32個雙向I/O口
4. 內置256字節RAM
5. 3個16位定時/計數器，支持中斷
6. 時鐘頻率支持0到24MHz
7. 2個串行中斷，帶可編程UART
8. 2個外部中斷，總共支持8個中斷源
9. 2條可編程讀寫控制線，支持3級加密
10. 支持低功耗空閑和掉電模式，能用軟件睡覺和喚醒
11. 封裝有PDIP、PQFP、TQFP、PLCC這些，方便各種板子用
引腳方面，AT89C52是標準的C51內核，封裝常見的有PDIP，跟普通8xC52差不多。主要管腳包括：
- XTAL1（19腳）和XTAL2（18腳）接晶振，一般外接12MHz
- RST/Vpd（9腳）是復位腳，靠電阻電容電路復位
- VCC（40腳）接+5V，VSS（20腳）接地
- P0到P3是通用I/O口，功能靠代碼定
比如在這個設計里：
- P0口（32~39腳）當N1控制口，連對應功能腳
- 13腳是IR接收輸入
- 10腳和11腳是I2C總線，連N1的SDAS和SCLS
- 12、27、28腳做握手信號，跟主板CPU通信，用來檢測制式和進入會聚調整狀態
P0口是8位漏極開路雙向口，可以當地址/數據復用總線。當輸出時，每個口能驅動8個TTL門電路；寫1時可作高阻輸入。訪問外部存儲器時，它會分時做低8位地址和數據總線，這時候內部上拉電阻會啟用。燒錄Flash時，P0負責接收指令字節；校驗時則輸出字節，但得外加上拉電阻。
P1口……

比如用1ms寬高電平作為“0”，2ms寬高電平作為“1”，低電平全為1ms就可以用來做單線通信。

/*合泰單片機*/
#define DATA _pa6
unsigned char nub[5]={0x01,0x0b,0xfe,0xcd,0xee};
unsigned char Receive[10]={0x00};
unsigned char Receivetime;
unsigned char ReceiveBF=0x00;
unsigned char Receivecount=0x00;
unsigned char ReceiveC=0x00;
void __attribute((interrupt(0x10))) isr_time(void)//100us 定時器中斷函數
{
_ptma0f=0;
switch(ReceiveBF)
{
case 0x00://引導碼低
{
if(DATA)
{
if(Receivetime>85)
{
if(Receivetime<100)
{
ReceiveBF=0x01;
Receivetime=0x00;
}
else
{
ReceiveBF=0x00;
Receivetime=0x00;
}
}
else
{
ReceiveBF=0x00;
Receivetime=0x00;
}
}
else
{
Receivetime++;
}
break;
}
case 0x01://引導碼高
{
if(DATA)
{
Receivetime++;
}
else
{
if(Receivetime>40)
{
if(Receivetime<55)
{
ReceiveBF=0x02;
Receivetime=0x00;
Receivecount=0x00;
ReceiveC=0x00;
}
else
{
ReceiveBF=0x00;
Receivetime=0x00;
}
}
else
{
ReceiveBF=0x00;
Receivetime=0x00;
}
}
break;
}
case 0x02://低電平
{
if(DATA)
{
if(Receivetime>10)//數據
{
if(Receivetime<25)
{
ReceiveBF=0x03;
Receivetime=0x00;
}
else
if(Receivetime<55)
{
ReceiveBF=0x04;
Receivetime=0x00;
}
}
}
else
{
Receivetime++;
}
break;
}
case 0x03://數據碼
{
if(DATA)
{
Receivetime++;
}
else
{
if(Receivetime>25)//1
{
Receive[ReceiveC]=Receive[ReceiveC]<<1;
Receive[ReceiveC]=Receive[ReceiveC]|0x01;
Receivecount++;
if(Receivecount==8)
{
Receivecount=0x00;
ReceiveC++;
}
ReceiveBF=0x02;
Receivetime=0x00;
}
else//0
{
Receive[ReceiveC]=Receive[ReceiveC]<<1;
Receive[ReceiveC]=Receive[ReceiveC]&0xfe;
Receivecount++;
if(Receivecount==8)
{
Receivecount=0x00;
ReceiveC++;
}
ReceiveBF=0x02;
Receivetime=0x00;
}
}
break;
}
case 0x04://結束碼
{
ReceiveBF=0x00;
Receivetime=0x00;
break;
}
}
}
void Send()
{
volatile unsigned char count=0x05;
volatile unsigned char datanub;
volatile unsigned char datacount;
//引導碼
DATA=0;
dly100us(90);
DATA=1;
dly100us(45);
//數據碼
while(count)
{
datanub=nub[5-count];
datacount=0x08;
while(datacount)
{
if(datanub&0x80)
{
DATA=0;
dly100us(15);
DATA=1;
dly100us(30);
}
else
{
DATA=0;
dly100us(15);
DATA=1;
dly100us(15);
}
datanub=datanub<<1;
datacount--;
}
count--;
}
//結束碼
DATA=0;
dly100us(45);
DATA=1;
dly100us(45);
DATA=0;
dly100us(45);
DATA=1;
}