Digispark红外接收器

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

#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

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; //
      case  69: DigiKeyboard.sendKeyStroke(KEY_ESCAPE); break; //
      case 81: DigiKeyboard.sendKeyStroke(KEY_HOME); break;
      case 21: DigiKeyboard.sendKeyStroke(KEY_LEFT_ARROW); break;//
      case 9: DigiKeyboard.sendKeyStroke(KEY_RIGHT_ARROW); break;//
      case 64: DigiKeyboard.sendKeyStroke(KEY_DOWN_ARROW); break;  //
      case 67: DigiKeyboard.sendKeyStroke(KEY_UP_ARROW); break;    //
    }
  }
}

/////////////////////////////////////////////////////////////
// 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

红外协议之NEC协议_Linux教程_Linux公社-Linux系统门户网站

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