Introduction: DIY USB IR Receiver

By
About: I'm an embedded ICT student.

In this tutorial, I'm going to show you how to make a small, cheap (less than $5) USB IR receiver.
The microcontroller used acts as a standard keyboard, so it should work on every computer.
With this receiver you can use a remote control to control things on your computer.

I made this instructables based on one of my previous instructables. The difference is that it's a lot smaller and it acts as a keyboard, so you don't need extra software on your PC.

Let's get started!

Step 1: Parts

For this instructables you'll need a few parts:

A digispark(clone) (gearbest)
A 38kHz IR receiver (ebay)
A remote control

You'll also need some tools:

A soldering Iron
A PC with the arduino software installed

Step 2: Soldering the IR Receiver

First you need to bend one leg (OUT) of the IR receiver so it goes into P2 and the other legs go into 5V and GND.

After that you need to add a little piece of heat shrink (or tape) to the horizontal part of the IR receiver.

Place the IR receiver back on the digispark and solder the three legs together.

The only thing you need to do now is clip of the useless part of each leg.

Now you're done with the hardware part.

Step 3: Getting the Keycodes of the Remote

In this part you need to see what code is "connected" to every button on the Remote control. We need to do this, because every remote uses other codes for every key.

To do this, I used the setup and program of my previous instructables. I just opened the serial monitor to see which code was send. If you don't have an arduino for getting the codes, you can also use the part you just made. This is a little more difficult, but it gives you the same result.

First you need to install the digiusb drivers. Goto this link and on the right click "download zip". After you've downloaded the zip extract all the folder "DigisparkExamplePrograms-master" to any directory you like.

The goto "DigisparkExamplePrograms-master/C++/DigiUSB Windows Driver/" and click "installdriver".

After you've done that, you need to follow these instructions to install the right boards in the arduino IDE.

Now copy this code to a new arduino project and upload it to your digispark.

/*************************************
* This code is written by Laurens Wuyts
* For questions: laurens.wuyts@gmail.com
* 
* 
* Microcontroller: ATtiny85
* Dev board:       Digispark
* 
*************************************/
#include <DigiUSB.h>

uint8_t situation = 0;
uint8_t START = 0;
uint8_t x = 0;
uint8_t BIT = 0;
uint8_t Id = 0;
uint8_t Id_inv = 0;
uint8_t Data = 0;
uint8_t Data_back = 0;
uint8_t Data_inv = 0;
uint8_t Repeat = 0;
uint8_t sended = 0;

uint16_t Time_old = 0;
uint16_t Time = 0;
uint16_t TimeDelta = 0;
 
void setup(void) {
  attachInterrupt(0, IR_Read, FALLING);
  
  pinMode(1,OUTPUT);
  digitalWrite(1,LOW);

  DigiUSB.begin();
}
 
void loop(void) {
  if(sended == 1) {
    DigiUSB.println(Data_back, DEC);
    sended = 0;
  } else {
    DigiUSB.delay(10);
  }
}

void IR_Read(void) {
  digitalWrite(1,HIGH);
  Time = micros();
  if (Time_old != 0) {
    TimeDelta = Time - Time_old;
    if ((TimeDelta > 12000)&&(TimeDelta < 14000)) {
      START = 1;
      x = 0;
      situation = 1;
      Id = 0;
      Id_inv = 0;
      Data = 0;
      Data_inv = 0;
    } else if ((TimeDelta > 10000)&&(TimeDelta < 12000)) {
      situation = 2; // repeat
    } else if ((TimeDelta > 1500)&&(TimeDelta < 2500)) {
      situation = 3; //"1"
      BIT = 1;
    } else if ((TimeDelta > 1000)&&(TimeDelta < 1500)) {
      situation = 3; //"0"
      BIT = 0;
    } else situation = 5; 
    if (situation == 3) {
      if (x < 8) {
        Id |= BIT;
        if (x < 7) Id <<= 1;  
        x++;
      } else if (x < 16) {
        Id_inv |= BIT;
        if (x < 15) Id_inv <<= 1;
        x++;
      } else if (x < 24) {
        Data |= BIT;
        if (x < 23) Data <<= 1;
        x++;
      } else if (x < 32) {
        Data_inv |= BIT;
        if (x < 31) {
          Data_inv <<= 1;
        } else {
          
          /* DO SOMETHING HERE */
          sended = 1;
          
          Data_back = Data;
          Repeat = 0;
        }
        x++;
      }
    } else if (situation == 2) {
      if(Repeat == 1) {
        
        /* DO SOMETHING HERE */
        /*sended = 1;*/
        
      } else {
        Repeat = 1;
      }
    }
  }
  Time_old = Time;
  digitalWrite(1,LOW);
}

After you've done that, goto "DigisparkExamplePrograms-master/Python/DigiUSB/Windows/" and open "monitor.exe". In this window the keycode is printed when you press a button. Just note the button and then the code you see. You'll need them later on.

Attachments

Step 4: Digispark Sketch

Ok now the "real" code for the Digispark.

In this code you need to add the keycodes you got in the previous step. For example if the "mute" key has code 100 you change:

#define mute	240
to 
#define mute	100

!! Attention !!

When you define a new key, you can't use spaces in the name.

And for adding functions go into the loop function and add/change the key you like.

When you have any question at all, feel free to ask!

/*************************************
* This code is written by Laurens Wuyts
* For questions: laurens.wuyts@gmail.com
* 
* 
* Microcontroller: ATtiny85
* Dev board:       Digispark
* 
*************************************/

/**** Define Remote control keys ****/
#define Power     64
#define key_1     32
#define key_2     160
#define key_3     96
#define key_4     16
#define key_5     144
#define key_6     80
#define key_7     48
#define key_8     176
#define key_9     112
#define key_0     136
#define vol_up    224
#define vol_down  208
#define ch_up     72
#define ch_down   8
#define mute      240
#define next      172
#define prev      164
#define up        6
#define down      134
#define left      166
#define right     70
#define playpause 156
#define key_stop  180
/************************************/

#include "TrinketHidCombo.h"

uint8_t situation = 0;
uint8_t START = 0;
uint8_t x = 0;
uint8_t BIT = 0;
uint8_t Id = 0;
uint8_t Id_inv = 0;
uint8_t Data = 0;
uint8_t Data_back = 0;
uint8_t Data_inv = 0;
uint8_t Repeat = 0;
uint8_t sended = 0;

uint16_t Time_old = 0;
uint16_t Time = 0;
uint16_t TimeDelta = 0;
 
void setup(void) {
  /* Use INT0(P2) on the Digispark */
  attachInterrupt(0, IR_Read, FALLING);
  
  pinMode(1,OUTPUT);
  digitalWrite(1,LOW);

  TrinketHidCombo.begin();
}
 
void loop(void) {
  if(sended == 1) {
    /* Assign functions to the buttons */
    if(Data_back == vol_up) {
      TrinketHidCombo.pressMultimediaKey(MMKEY_VOL_UP);
    } else if(Data_back == vol_down) {
      TrinketHidCombo.pressMultimediaKey(MMKEY_VOL_DOWN);
    } else if(Data_back == next) {
      TrinketHidCombo.pressMultimediaKey(MMKEY_SCAN_NEXT_TRACK);
    } else if(Data_back == prev) {
      TrinketHidCombo.pressMultimediaKey(MMKEY_SCAN_PREV_TRACK);
    } else if(Data_back == key_stop) {
      TrinketHidCombo.pressMultimediaKey(MMKEY_STOP);
    } else if(Data_back == playpause) {
      TrinketHidCombo.pressMultimediaKey(MMKEY_PLAYPAUSE);
    } else if(Data_back == mute) {
      TrinketHidCombo.pressMultimediaKey(MMKEY_MUTE);
    } else if(Data_back == Power) {
      TrinketHidCombo.pressSystemCtrlKey(SYSCTRLKEY_SLEEP);
    } else if(Data_back == key_0) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_0);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_1) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_1);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_2) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_2);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_3) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_3);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_4) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_4);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_5) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_5);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_6) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_6);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_7) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_7);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_8) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_8);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == key_9) {
      TrinketHidCombo.pressKey(KEYCODE_MOD_LEFT_SHIFT, KEYCODE_9);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == up) {
      TrinketHidCombo.pressKey(0, KEYCODE_ARROW_UP);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == down) {
      TrinketHidCombo.pressKey(0, KEYCODE_ARROW_DOWN);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == left) {
      TrinketHidCombo.pressKey(0, KEYCODE_ARROW_LEFT);
      TrinketHidCombo.pressKey(0, 0);
    } else if(Data_back == right) {
      TrinketHidCombo.pressKey(0, KEYCODE_ARROW_RIGHT);
      TrinketHidCombo.pressKey(0, 0);
    }
    sended = 0;
  } else {
      TrinketHidCombo.poll();
  }
}

/* Read the IR code */
void IR_Read(void) {
  digitalWrite(1,HIGH);
  Time = micros();
  if (Time_old != 0) {
    TimeDelta = Time - Time_old;
    if ((TimeDelta > 12000)&&(TimeDelta < 14000)) {
      START = 1;
      x = 0;
      situation = 1;
      Id = 0;
      Id_inv = 0;
      Data = 0;
      Data_inv = 0;
    } else if ((TimeDelta > 10000)&&(TimeDelta < 12000)) {
      situation = 2; // repeat
    } else if ((TimeDelta > 1500)&&(TimeDelta < 2500)) {
      situation = 3; //"1"
      BIT = 1;
    } else if ((TimeDelta > 1000)&&(TimeDelta < 1500)) {
      situation = 3; //"0"
      BIT = 0;
    } else situation = 5; 
    if (situation == 3) {
      if (x < 8) {
        Id |= BIT;
        if (x < 7) Id <<= 1;  
        x++;
      } else if (x < 16) {
        Id_inv |= BIT;
        if (x < 15) Id_inv <<= 1;
        x++;
      } else if (x < 24) {
        Data |= BIT;
        if (x < 23) Data <<= 1;
        x++;
      } else if (x < 32) {
        Data_inv |= BIT;
        if (x < 31) {
          Data_inv <<= 1;
        } else {
          
          /* DO SOMETHING HERE */
          sended = 1;
          
          Data_back = Data;
          Repeat = 0;
        }
        x++;
      }
    } else if (situation == 2) {
      if(Repeat == 1) {
        
        /* DO SOMETHING HERE */
        sended = 1;
        
      } else {
        Repeat = 1;
      }
    }
  }
  Time_old = Time;
  digitalWrite(1,LOW);
}

Now upload the sketch to the digispark. Unplug and replug it into your computer, wait ~5sec and enjoy your remote control.

Attachments

Step 5: Resume

In this tutorial, I showed how to make a low cost USB remote control.

I hope you liked it, please add suggestions what you want to see next, questions or improvements below.

Laurens