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Control your computer with an infrared remote control By Tim Blythman Don’t have a “Smart TV”? Even if you do, you may want to connect a computer to your TV for playing videos, music, games, viewing photos, web browsing and so on. This is known as a home theatre PC (HTPC). But operating a keyboard and mouse from the couch is clumsy. Why not use an infrared remote control for important functions like play, pause, next track, etc? It’s surprisingly easy to do! L ike many tech-savvy people, I have a computer hooked up to my TV. I use it mainly for watching DVDs and YouTube videos on the big screen. I can even play games or surf the net. But if I’m sitting back watching a movie and I want to pause it to get a drink, I don’t want to fiddle around with a wireless mouse or keyboard. I have trouble with my wireless mouse since its range is only just good enough to reach from the couch to the TV, so it doesn’t work reliably. And I often forget to turn it off after using it, prematurely flattening its batteries. An infrared remote control is far better suited to that sort of task and you probably already have one (or many!) at hand, which are likely to have some spare buttons which you could re-assign for various purposes. It’s so much easier to just pick it up and press a button. You may already have the parts needed to build this project. There’s hardly any assembly required since it only involves two components. You can use it with a wide range of remote controls, including inexpensive generic programmable remotes. How does it work? If you’re familiar with the Arduino Leonardo’s capabilities, you might You might own a HTPC, like the ASUS PB40, or have built your own to use with a TV. While useful, it can be a pain to control using traditional means. That's why we've come up with a way to use a standard IR remote to control it. 66 Silicon Chip Australia’s electronics magazine have an inkling as to how we achieve the computer interface. The Leonardo has a USB interface and it can be set up to appear, from the computer’s point of view, as a USB keyboard and/ or mouse. This is also true of other ATmega32U4-based Arduino boards; there are a few. So then we just need to arrange to receive infrared commands and we can translate them into keystrokes or mouse movements/clicks. The Leonardo remains attached to the computer’s USB port (you can even use it with a Raspberry Pi) so it doesn’t need any external source of power. The only difficulty is knowing what codes to expect from the remote control. For this, we can temporarily set up the Leonardo to tell us what codes it is receiving. We’ve already done this with a remote control that’s available from Jaycar so you can simply use the codes we provide and get the remote control up and running in minutes. It sounds simple, but the devil is in the detail. What keystrokes do we need to emulate? And how do we send them? Hardware As we mentioned, we can use pretty much any ATmega32U4-based Arduino siliconchip.com.au allow us to emulate a keyboard (github. com/arduino-libraries/Keyboard) and a mouse (github.com/arduino-libraries /Mouse). The only remaining hard part is deciding which infrared code corresponds to which action. With most of the complex function hidden in the libraries, our software sketch mainly deals with reading the codes from the infrared receiver library and then feeding the appropriate actions to the keyboard and mouse emulation libraries. Construction This remote control from Jaycar Electronics (XC3718) has 21 keys, each of which generates a different code based on the NEC IR protocol. These codes are detected and converted into keystrokes or mouse actions. board, including the “Leonardo” or the smaller “Leostick” version that’s available from Jaycar. If space is at a premium, there is a variant known as a “Micro”, and an even smaller (clone) version, which can be found under the name “Beetle”. The Beetle isn’t much bigger than most other USB dongles, so should fit just about anywhere. A 3-pin IR receiver module can then be attached to the Arduino board, so we can now receive the signals from our remote control. Software Fortunately, there are a number of libraries available that already do most of the hard work for us. The first one (IRremote; github.com/z3t0/ArduinoIRremote) is used to receive and decode the infrared signals, giving us a different code for each button that’s pressed on the remote control. This is a great library that can also be used to transmit infrared signals. The two other libraries we’re using The Beetle can just be plugged into a USB type-A port on a computer, as is. siliconchip.com.au There isn’t much to the hardware so it makes sense to assemble it first. The hardware can be used for figuring out what code is generated by each remote control button, and then re-used as the actual IR/keyboard/mouse interface. We built two prototypes using different Arduino modules as follows. A tiny Beetle The Arduino Beetle variant is a minimal ATmega32U4-based board designed by DFRobot. Although it hasn’t been around for long, it has been “cloned” and these clones are available from many online stores. We don’t even need to solder the supplied headers to it. We can simply solder the infrared receiver straight to the pads on the board. When complete, the final unit is smaller than most USB flash drives. The infrared receiver’s GND pin is soldered to the GND pad on the PCB, the Vcc pin to the 5V pad and the DATA pin to digital input D11. The infrared receiver library can use any digital pin as the input but this is the one that we have chosen. Most infrared receiver modules use the same pinout (including those sold by Jaycar and Altronics) so you can most likely solder yours as shown here. But if you're using a receiver from a different source, it would be a There are a few variants of Arduino compatible boards that will work with this project, like the ProMicro pictured. Compatible boards need to be based on the ATmega32U4 processor which has a built-in USB interface. good idea to double-check the data sheet. Looking at the lens from the front with the leads at the bottom, the pins from left-to-right are DATA, GND and Vcc. If you like, you can carefully twist the receiver so that it will face the right way (towards the couch you are comfortably sitting on) when plugged into the computer. As long as the wires don’t touch, you should have no troubles. Use heatshrink insulation if in doubt. A larger variant If you have an Arduino-compatible Leonardo or Micro board lying around for prototyping, it is entirely possible to put this project together without any soldering. Perhaps you just want to test out that it does what you want before assembling something more permanent. In that case, we can use an Arduinocompatible module and some jumper leads to quickly put everything together. It may not be as compact but if your other family members don’t mind bits of electronics sitting near the TV, it will work just as well as the Beetle version. We also happened to have an infrared receiver assembly that includes the actual receiver module plus an onboard LED. This This IR receiver module is a great way to get up and running quickly. It also has an onboard LED to indicate when it is receiving a signal. You can then pair this with the Arduino Leonardo shown right, an Arduino Micro or similar device. Australia’s electronics magazine August 2018  67 spreadsheet or other document for use in our next step. Using a spreadsheet makes it easy to assign a name to each code for later reference. Keep in mind that the buttons you use on the remote shouldn’t be used for anything else, even if the TV is in a different mode. Otherwise, the TV and computer might both respond to the same button press, with unexpected results. Finding out which key codes to generate Finding out the codes that an IR remote control uses is as simple as opening a spreadsheet program and loading our “IR_Code_Typer.ino” sketch, which types the received codes directly into a spreadsheet. means that you can easily see if it’s receiving a signal or not. If using such a module, check the markings on it to see which pins are which. They generally have an “S” to identify the data pin and a “-” for the ground pin, with the unmarked middle pin being positive 5V supply. Run a jumper lead from the “S” pin to D11 on the Leonardo (we’ve used blue), “-” to GND (grey) and the middle pin to 5V (violet). Getting the codes If you aren’t using the Jaycar remote control, you will need to figure out which codes are produced by each button that you intend to use. We’ve written a brief sketch which looks for signals from the infrared receiver and then types that code out on the PC using the emulated keyboard. You can dump the codes into a ◄ 68 Silicon Chip Having determined what button you’ve pressed on the infrared remote, the Arduino code then needs to know which key or button press to generate in turn. This will depend on the software that you’re running on the PC. I use the VLC media player for watching videos on my HTPC. It’s free and for the most part, it just works. If you use a different player, it will probably have a different set of keyboard shortcuts although most seem to use the space bar to play/pause. If in doubt, open your player of choice and mash away at the keyboard until you find out what key does what! The commands that I wanted to use for VLC are: play/pause, toggle fullscreen mode, skip backwards and forwards. There’s a great guide to all the shortcut keys at https://wiki.videolan. org/Hotkeys_table/ The keys I needed are in the first dozen listed, so this information was easy to establish. The Jaycar remote control I used Wiring diagram for the Arduino Leonardo version. We used an IR receiver module for the Leonardo, which can then be hooked up via flying leads or similar. only has a single play/pause toggle button, so I had to settle for using the space key to toggle between play and pause. Toggling fullscreen involves simply pressing the “F” letter key. For skipping forwards and backwards, we have the choice between very short, short, medium and long jumps. According to the application's settings, a short jump is 10 seconds, which sounds like a good amount and is accessed using the Alt-Left Arrow or Alt-Right Arrow key combinations. Sending keystrokes to a PC The Arduino keyboard library is fairly easy to use. For example, to send the “F” keypress for toggling fullscreen mode, we can simply use this line of code: Keyboard.write(‘f’); It’s almost as though we are printing a character to the serial monitor. But for key combinations like Alt-Left Arrow, it’s not quite so easy. There are two catches here. One is that we are sending a non-printing key (ie, the arrow key) and the second is that we’re sending a key modifier (Alt). This web page gives an overview of all the special keys: www.arduino. cc/en/Reference/KeyboardModifiers This tells us that to send a Left Arrow keypress, we can use the following code: Keyboard.write( KEY_LEFT_ARROW); ◄ Wiring diagram for the smaller Arduino Beetle remote receiver. The pins of the IR receiver can just be inserted directly into the Beetle and soldered. The DATA pin on the IR receiver can go to any free digital pin on the Arduino, but you'll need to change the software to match which pin you're using if not D11. Australia’s electronics magazine siliconchip.com.au To send Alt-Left Arrow, we need to send the computer the correct key presses and releases in the correct order, with a slight delay, as that is how the computer is expecting to receive them (as though a real human was pressing the keys): Keyboard.press(KEY_LEFT_ALT); Keyboard.press( KEY_LEFT_ARROW); delay(100); Keyboard.releaseAll(); This is a bit involved but it gives us a lot of flexibility. For example, you could use the following code sequence to run any Windows program (in this case Notepad) using the WIN+R shortcut: Keyboard.press(KEY_LEFT_GUI); Keyboard.press(‘r’); delay(100); Keyboard.releaseAll(); delay(200); Keyboard.print(“notepad”); Keyboard.write(KEY_RETURN); If you’re going to use a sequence like this, it’s a good idea to test it individually before mapping it to an infrared remote button and remember that the computer may respond differently if a different program has the focus (ie, is in the foreground) when the sequence is activated. For sequences which start with a press of the “Windows Key”, like the one immediately above, this should not be a problem as they are captured by the operating system, regardless of which program is in the foreground. But it it’s also worth testing what happens if a certain keystroke occurs under a different program. What about the mouse? As we mentioned, there’s also the possibility of emulating mouse movements and button presses. If you have a spare group of five or even nine buttons on the remote control, it’s possible to use them to move the mouse cursor around and click. The library provides two different functions to control the mouse. The simplest is: Mouse.move(x,y); This simply moves the mouse pointer in the x and y directions by the number of pixels specified. If x is negative, the pointer moves left and if x is positive, the pointer moves right. Up is siliconchip.com.au By changing the value highlighted, we can change which infrared code/button press the Leonardo responds to. For this line of the sketch, if the current code matches, a signal is sent to the computer to move the mouse pointer ten pixels to the right. To manually install the libraries (rather than using the library manager), unzip or copy them into the Arduino libraries folder. This can be found by going to the File → Preferences menu in the Arduino IDE and looking for the "Sketchbook location", as shown above. The libraries are stored in a subfolder at this location. negative on the y-axis. To simulate a left-click, you can use: Mouse.click(); If you want to click a different button, do it like this: Mouse.click(MOUSE_RIGHT); Note that all mouse movements are relative. You can’t send a command to move the pointer to a particular position on the screen. If you have to do this, you might be able to come up with a scheme where you move the mouse into one corner of the screen and then move it relative to that point, but we won’t go into details as we haven’t tried it. In practice, the best way to implement mouse cursor control with an infrared remote is to have a button each for up, down, left, right and click. Extra buttons, if available, can be used for diagonal movements. This makes steering the pointer feel a bit like playing an old video game Australia’s electronics magazine with a joystick but it is fine for some basic screen navigation, eg, to select a video to play. Getting the infrared codes If you are using the suggested Jaycar remote control and already have the Arduino IDE installed, jump ahead to “Uploading the main sketch”. If you have an existing remote control you would like to make work, you will first need to upload the “IR_Code_ Typer” sketch to find out what codes correspond to what keys. To compile and upload the software that runs on the board, we need to have the Arduino IDE (Integrated Development Environment) installed. This can be downloaded from www. arduino.cc/en/main/software for Windows, macOS and Linux. Download and install a version to suit your operating system and start the Arduino IDE. You will need at least version 1.6.4 to use the Library Manager in the next step. August 2018  69 Open the Library Manager by going to the Sketch → Include Library → Manage Libraries menu and search for “irremote”. When you find it, click on the install option that is presented. If the Library Manager is not working or not available, you have the option of installing the IRremote.zip library supplied in our download package using the “Add .ZIP Library” option in that same menu. Now plug the device into a USB port on the computer and select the board’s serial port in the Tools → Port menu. Observe whether the board is seen as a “Leonardo” or “Micro” and based on this, select either “Arduino Leonardo” or “Arduino/Genuino Micro” under the Boards menu. If you choose the wrong option it simply won’t work, so if in doubt try one or the other. Before uploading the code, open a text editor such as Notepad or Leafpad, as the board becomes a keyboard device immediately after the upload completes. Now open the IR_Code_Typer.ino sketch file, which you will have extracted from our download package, then click “Upload” (or press CTRL+U on your keyboard). Assuming the upload completes successfully, switch to the text editor that you opened earlier, then point your infrared remote control at the unit and press one of the buttons. You should see a hexadecimal value appear and pressing a different button should give you a different code. You may also get different codes if you hold the button down. A good way to record the codes is to open a spreadsheet program and create a list with the button names that you want to use in the first column. Then move the cursor to the top of the second column and press each remote control button in turn, corresponding to the names in the first column. The code should appear in that cell and the cursor will move to the next cell below. Uploading the main sketch You might like to try uploading the sketch to the board without making any changes, just to check that everything works as it should. The sketch code we have created will work with the Jaycar XC3718 remote control pictured earlier, but can be supplemented with your own codes. 70 Silicon Chip By default, it uses the numbers 1-9 as a joystick type interface, with the 5 key being the same as a left mouse click and the other numbers moving the pointer in different directions by 10 pixels at a time. For example, number 4 is to the left of centre so it will move the mouse to the left. We’ve also set up the Play/Pause button to emulate a spacebar press and the Previous and Next buttons generate Alt-Left and Alt-Right keypresses respectively. These last two correspond to forward and back on many web browsers too. If you are using a different remote control or want to change what the buttons do, you will need to modify the code. Specifically, you will be modifying the series of “if” statements which check to see which IR code has been received and then perform an appropriate action. Before making any modifications, save the Sketch file under a different name so that you don’t overwrite the original. Using your spreadsheet as a reference, replace the hexadecimal value in each “if” statement with one of the button codes that you noted earlier. Then, inside the braces that follow that if statement, you will need to change or add the code to send the necessary keyboard or mouse events to the computer. For example, let’s say that in response to button code 0xFF1234 being received, you want to generate a keypress equivalent to pressing CTRL+ALT+t on the keyboard. Your new “if” statement would look like: if (code == 0xFF1234) { Keyboard.press( KEY_LEFT_CTRL); Keyboard.press(KEY_LEFT_ALT); Keyboard.press(‘t’); delay(100); Keyboard.releaseAll(); code=0; } The “code=0;” line towards the end should be included if you do not want the action to be repeated if the key is held down. If you do want it to repeat, leave that bit out. Once you have done this with all the buttons you want to use on the remote and removed any extraneous “if” statements which may be left over from the original code, you can Australia’s electronics magazine proceed to upload this sketch to the main board. You can handle codes from multiple remote controls in the same sketch. Having uploaded the sketch, check that it works as expected. If you find any keys are not responding or not doing what you think they should, check the code in the “if” statements. Finalising the code You might notice in the codes that we check for 0xFFFFFFFF. This is a code emitted by remote controls that use the NEC encoding which indicates that the current key is being held down and the effect of that key should be repeated. We implement this by saving the code of whatever key was last pressed and then substituting that code if a repeat code is seen. What next? It’s a very useful device as described, but these Arduino boards have a number of spare pins and you could use these for other tasks that can also be controlled by the remote control. For example, you could wire up some LEDs and arrange for remote buttons to switch them on and off for some instant mood lighting. You could even consider integrating some code to switch remote power points on and off. You could do this using some Arduino code provided by Jaycar which works with the wireless power point switches. This can be downloaded from www.jaycar.com. au/iot-wireless-switch SC Parts List 1 infrared remote control (eg, Jaycar XC3718) 1 infrared receiver module (eg, Jaycar ZD1952, Altronics Z1611A) Beetle-based version 1 DFRobot Beetle or equivalent (ProMicro etc) Leonardo-based version Arduino Leonardo board or equivalent (eg, Jaycar XC4430, Altronics Z6214) 1 set of plug-socket breadboard leads (eg, Jaycar WC6028, Altronics P1017) siliconchip.com.au