Auto-pause your TV

I'm often tired when I sit down to watch TV at the end of a day, so I want the experience to be as easy as possible. One simple improvement I've dreamt about is having the TV notice when I've got up so it can automatically pause the current show, and then resume it when I return. I decided to prototype this using one of our Person Sensors, together with a Circuit Playground Express board from Adafruit. This guide will show you how to build one too, with no soldering required!

The video above shows how the final device works. When no face is detected for five seconds, an IR signal is sent to the TV emulating pressing the pause button on your remote control. When a face is detected again for at least one second, the code for play is sent. It's definitely still a prototype, with lots of rough edges to be smoothed out, but I've had fun playing with it myself and demoing it to other people. I'd love to see a commercial product like this, so I hope it sparks someone's imagination.

Equipment

You need to make sure you get the "Express" version of the Circuit Playground board, because this is the only one with a built-in IR transmitter and receiver. You can probably adapt this to other boards with external IR modules, but you'll need to figure out how to interface them with the Arduino IDE. The slightly more expensive base kit includes a CPX board, and also some nice extras like a battery pack and cable. I also like the official transparent case, you can see it in the photos and videos.

Assembling

Wiring up the sensor requires a cable with a Qwiic/Stemma QT connector on one end, and four alligator clips on the other. These clips connect VDD, GND, SDA and SCL from the sensor to the board. First plug in the connector to the sensor. This should only connect one way round, with the exposed metal facing the board.

The alligator clips then connect to four tabs on the Circuit Playground. If the side with the buttons and components on is facing you, you start at the 11 o'clock position with GND (black), the anti clockwise with SDC (yellow), then SDA (blue), and finally 3.3V (red). Here's a wiring diagram:

Once the Circuit Playground is plugged into USB, you should see the green light on the person sensor glow when a face is visible.

Mounting

The Person Sensor needs to be mounted on the back of the board, on the opposite side to the buttons. This will be looking back at you on the couch, while the IR transmitter on the other side sends commands to the TV to play or pause depending on whether you're around. I bought an enclosure and used Blu Tack to mount the sensor in the right position, but I'm sure those of you more skilled can come up with a more elegant solution.

Arduino Setup

We're going to be using the Arduino IDE to build and flash our program. Download the version for your OS to start. There's an official Adafruit guide to installing what you need for a Circuit Playground Express, but don't followit! It uses the more limited Arduino version of the board package, which doesn't support a lot of the CPX's features. Instead, you'll need to install the Adafruit version of the board package.

To do this, you'll need to first add https://adafruit.github.io/arduino-board-index/package_adafruit_index.json to the Additional Boards Manager URLs field in the Arduino preferences window.

Once this is set, go to Tools->Board->Boards Manager... in the Arduino IDE and search for "Adafruit SAMD". You should see a package called "Adafruit SAMD boards" which includes the Circuit Playground Express in its description.

Make sure that you install the Adafruit version, not the default Arduino package, since only the Adafruit board library has full support for all of the CPX's peripherals.

Next, we'll need to install a library to store information about any recorded IR codes even when the board is powered down. Go to Tools->Manage Libraries and add "FlashStorage" to your Arduino libraries.

Flashing the Code

If you're familiar with git you can download the code in this repository from github.com/usefulsensors/person_sensor_tv_remote but don't worry if not, you can get it all as a ZIP file too. Once you have the code on your local machine, open the person_sensor_tv_remote.ino file in the Arduino IDE. Make sure that your Circuit Playground Express board is connected by USB to your computer, and that you've selected the right port from the Tools->Port menu, and that you have selected "Adafruit Circuit Playground Express" as the board. Once that's all set up, press the upload button (an arrow pointing right in the top left of the IDE) to compile and flash the program.

Setting up the Board

The system is designed to send the same IR code as the play button when it spots a person nearby, and the pause IR code when nobody seems to be around. Because different TVs use different codes, you'll probably need to tell the device what the codes are for your model. The sketch defaults to codes that work with most Samsung TVs when it's first flashed onto the board, but you can record new ones from your own remote.

Testing the Board

Before you try it out on your TV, it's a good idea to make sure the basic functionality is working. You can do this by pointing the person sensor at your face, and making sure the green light on the board comes on. Then point the sensor away from you or cover the lens, watch the green light go off, and wait a few seconds. You should hear the speaker on the board say "Pause", though it is quite quiet and can be hard to understand. If you then point the sensor back at your face for a second or so, you should hear "Play". This shows the device is correctly pausing when nobody is around, and playing when they return.

Recording your Remote

If you're not using a Samsung TV, you'll need to record the correct IR codes for your brand from your existing remote. These days a lot of higher end models are moving towards Bluetooth connections, which I'll cover in a future project, but most at least still understand IR codes. If you find you can't record, it's possible to update the sketch to default to the right codes, if you can find information about them online. Searching can be confusing though, since the codes aren't the same as the ones used to program universal remotes.

If you have an IR remote, you can get started by pressing the left button on the board. You should "Recording, press play", and see the board's LEDs light up in a counter-clockwise pattern. Point your remote at the front of the board and press the play button. Once the board recognizes it, the speaker will say "Press pause", and the LEDs will rotate clockwise. When that code has been recognized, the board will say "Done". These values will be saved in flash, so if you power down and restart the board, they will be remembered. They are reset to the default values if you flash the sketch again though.

Auto-pausing your TV

Now that you've got everything set up, you can sit back, relax, and let the board take care of controlling your TV! The person sensor has a useful range of about two meters, or six feet, so make sure that the sensor is facing you on somewhere like a coffee table, with the front of the board (which has the IR transmitter and receiver) pointing at the screen. You should see the green LED on the sensor light up when it sees you, and if no face is seen for five seconds it will send the pause IR code. Then, when a face is seen continuously for at least a second, the play code will be sent. The idea is that it should pause when you get up off the couch, and play again once you've settled back down.

This is definitely still a prototype though, both the sensor and this sketch are very much works in progress, so you may well want to tweak the code to make it a better fit for you. If you look in the sketch, you can change constants like pauseDelaySeconds and playDelaySeconds to adjust the timing, or get more advanced by altering the logic around what it takes to trigger playing and pausing.

You can also find out more information about how the Person Sensor works from the developer guide, including its facial recognition features, which might be useful for improving how this project works.