一、红外协议之NEC协议原理
NEC协议格式：
首次发送的是9ms的高电平脉冲，其后是4.5ms的低电平，接下来就是8bit的地址码（从低有效位开始发），而后是8bit的地址码的反码（主要是用于校验是否出错）。然后是8bit 的命令码（也是从低有效位开始发），而后也是8bit 的命令码的反码。
/* 以脉宽为低电平0.565ms、间隔高电平0.56ms、周期为1.125ms的组合表示"0"; */
/* 以脉宽为低电平0.565ms、间隔高电平1.685ms、周期为2.25ms的组合表示"1"。 */
二、解码KM-001红外遥控器
平台：Digispark kickstarter 微型 Arduino usb 开发板 ATTINY85
采集到第17个到第24个高电平的脉冲时间如下：
706
1753
1694
674
1694
639
702
571
01101000=>22
![clip_image002[4]](https://images0.cnblogs.com/blog/742657/201504/260202416974617.jpg "clip_image002[4]")
#include "DigiKeyboard.h" int irPin = 2; //Sensor pin connect to digital pin2 (ATINY85 pin7) int start_bit = 2200; //Start bit threshold (Microseconds) int bin_1 = 1000; //Binary 1 threshold (Microseconds) int bin_0 = 400; //Binary 0 threshold (Microseconds) const byte BIT_PER_BLOCK = 32; void setup() { pinMode(irPin, INPUT); } void loop() { DigiKeyboard.update(); //keep on updating the keyboard // this is generally not necessary but with some older systems it seems to // prevent missing the first character after a delay: DigiKeyboard.sendKeyStroke(0); int key = getIRKey(); //Fetch the key if(key != 0) //Ignore keys that are zero { DigiKeyboard.print("=>"); //uncomment this if you want to DigiKeyboard.println(key); //print out the value of the button } } ///////////////////////////////////////////////////////////// // decode infrared signal ///////////////////////////////////////////////////////////// int getIRKey() { int data[BIT_PER_BLOCK]; int i; while(pulseIn(irPin, HIGH) < start_bit); //Wait for a start bit for(i = 0 ; i < BIT_PER_BLOCK ; i++) data[i] = pulseIn(irPin, HIGH); //Start measuring bits, I only want HIGH pulses delay(100); //add by tingpan /* for(i = 16 ; i < 24; i++) { DigiKeyboard.println(data[i]); //print out the value of button in binary form //if(data[i] == 1) result |= (1<<i-16); } */ for(i = 0 ; i < BIT_PER_BLOCK ; i++) //Parse them { if(data[i] > bin_1) //is it a 1? data[i] = 1; else if(data[i] > bin_0) //is it a 0? data[i] = 0; else return -1; //Flag the data as invalid; Return -1 on invalid data } //based on NEC protocol, command data started from bit 16 //and end with bit 24 (8 bits long) int result = 0; for(i = 16 ; i < 24; i++) { DigiKeyboard.print(data[i]); //print out the value of button in binary form if(data[i] == 1) result |= (1<<i-16); } return result; //Return key number }
三、红外控制电脑键盘相关按钮
平台：平台：Digispark kickstarter 微型 Arduino usb 开发板 ATTINY85
代码：
#include "DigiKeyboard.h" // not all keys are mapped in the DigiKeyboard.h file. // you have to map it here #define KEY_HOME 0x4A #define KEY_PAGE_UP 0x4B #define KEY_PAGE_DOWN 0x4E #define KEY_ESCAPE 0x29 #define KEY_UP_ARROW 0x52 #define KEY_DOWN_ARROW 0x51 #define KEY_LEFT_ARROW 0x50 #define KEY_RIGHT_ARROW 0x4F //defined by tingpan #define KEY_ESC 0x1B #define KEY_UP 0x26 #define KEY_DOWN 0x28 #define KEY_LEFT 0x25 #define KEY_RIGHT 0x27 #define KEY_LEFT_CLIK 0x01 #define KEY_RIGHT_CLIk 0x02 int irPin = 2; //Sensor pin connect to digital pin2 (ATINY85 pin7) int start_bit = 2200; //Start bit threshold (Microseconds) int bin_1 = 1000; //Binary 1 threshold (Microseconds) int bin_0 = 400; //Binary 0 threshold (Microseconds) const byte BIT_PER_BLOCK = 32; void setup() { pinMode(irPin, INPUT); } void loop() { DigiKeyboard.update(); // keep updating the keyboard // this is generally not necessary but with some older systems it seems to // prevent missing the first character after a delay: DigiKeyboard.sendKeyStroke(0); int key = getIRKey(); //Fetch the key if(key != 0) //Ignore keys that are zero { //DigiKeyboard.print("=>"); //uncomment this if you want to //DigiKeyboard.println(key); //print out the value of the button switch(key) { case 12: DigiKeyboard.println("1"); break; case 24: DigiKeyboard.println("2"); break; case 94: DigiKeyboard.println("3"); break; case 8: DigiKeyboard.println("4"); break; case 28: DigiKeyboard.println("5"); break; case 90: DigiKeyboard.println("6"); break; case 66: DigiKeyboard.println("7"); break; case 82: DigiKeyboard.println("8"); break; case 74: DigiKeyboard.println("9"); break; case 22: DigiKeyboard.println("0"); break; case 68: DigiKeyboard.sendKeyStroke(KEY_SPACE); break;//can stop or continue case 7: DigiKeyboard.sendKeyStroke(KEY_ENTER); break; // enter case 69: DigiKeyboard.sendKeyStroke(KEY_ESC); break; //can't use case 70: DigiKeyboard.sendKeyStroke(KEY_HOME); break; //Mode case 64: DigiKeyboard.sendKeyStroke(KEY_LEFT_ARROW); break;// <-- case 67: DigiKeyboard.sendKeyStroke(KEY_RIGHT_ARROW); break;//--> case 21: DigiKeyboard.sendKeyStroke(KEY_DOWN_ARROW); break; //down case 9: DigiKeyboard.sendKeyStroke(KEY_UP_ARROW); break; //up case 25: DigiKeyboard.sendKeyStroke(KEY_LEFT_CLIK); break; //can't use case 13: DigiKeyboard.sendKeyStroke(KEY_RIGHT_CLIk); break; //can't use } } } ///////////////////////////////////////////////////////////// // decode infrared signal ///////////////////////////////////////////////////////////// int getIRKey() { int data[BIT_PER_BLOCK]; int i; while(pulseIn(irPin, HIGH) < start_bit); //Wait for a start bit for(i = 0 ; i < BIT_PER_BLOCK ; i++) data[i] = pulseIn(irPin, HIGH); //Start measuring bits, I only want HIGH pulses delay(100); for(i = 0 ; i < BIT_PER_BLOCK ; i++) //Parse them { if(data[i] > bin_1) //is it a 1? data[i] = 1; else if(data[i] > bin_0) //is it a 0? data[i] = 0; else return -1; //Flag the data as invalid; Return -1 on invalid data } //based on NEC protocol, command data started from bit 16 //and end with bit 24 (8 bits long) int result = 0; for(i = 16 ; i < 24; i++) { //DigiKeyboard.print(data[i]); //print out the value of button in binary form if(data[i] == 1) result |= (1<<i-16);// convert="" data="" bits="" to="" integer } return result; //Return key number }
参考：
STC的51单片机红外遥控器读码、发射程序，已试成功 - 第1页 - wxleasyland's Blog - EDN China电子设计技术