Network control of window shades using relays, a Raspberry Pi Zero, and Node JS

At my church, we have a smaller auditorium that has a giant window to let in natural light. We don’t use it much during services because the light can wash out our projection screens, but it’s wonderful to have during the week to let in light. We also like to have it open before services begin and close it right as we get started. It helps to create a nice environment.

These shades came with a very easy to use RF remote. Actually, it came with two remotes. Since we never need or use two, I thought, wouldn’t it be cool to hack one of them and turn it into a network-controlled remote? This would allow us to control the shades from anywhere, not just within the RF range! Plus, I like automation and making things more accessible and efficient and I wanted to try to create something inexpensive rather than just purchasing something already made.

I purchased this USB relay off Amazon:

I figured I could use the relays to electrically “click” the buttons on the remote. So I took the remote apart to see how it looked on the inside. Here is a picture of the remote outside of its shell.

I knew there was probably a way to use the GPIO pins of a Raspberry Pi and transistors to trigger the button presses, but that’s not my forte. I don’t know a lot about circuity and electronics at that level, but I know how to solder (well, sort of. Don’t look too closely at my work.) So I soldered some wires onto the remote buttons.

When I touched the wires together, the remote activated! The concept worked, so I hooked it up to the relay to begin the development and testing.

I knew I wanted to control the remote using Node JS. It’s a great lightweight platform that runs on multiple operating systems, including Raspberry Pi’s with Linux. I found control software written in C, C++, Python, shell scripts, etc. for the USB Relay that I had bought, but nothing in Node JS. At least, nothing native without using DLLs and that sort of thing.

It’s been a long time since I wrote in C++ and I’ve never used Python, but I can read both languages enough to learn about the control protocol. I wanted to keep mine running with the least amount of dependencies so it could work on multiple operating systems (not just on the Raspberry Pi, for example).

In about an hour, using the Node-HID library, I had a working script in Node JS to turn my 2-relay device on and off. I decided to make the control code for the relay into a separate Node JS module so that it can be used in other projects. If you want to use it, I’ve made it available on Github as well as published it in the NPM registry.

Once I had the control of the relay that I needed, I whipped up a quick Node JS project running express to host a simple web server that would accept a “shades up” and a “shades down” HTTP request and then trigger the appropriate relay.

const USBRelay = require("./USBRelay.js");
const relay = new USBRelay();

//express API variables
const express = require('express');
const app = express();

//http server variables
const http = require('http').Server(app);
const listenPort = 4400;

//routes

app.get("/shades_up", function (req, res) {
   ShadesUp();
   res.send({returnStatus: "shades-up"});
});

app.get("/shades_down", function (req, res) {
   ShadesDown();
   res.send({returnStatus: "shades-down"});
});

http.listen(listenPort, function () {
    console.log("listening on *:" + listenPort);
});

function ShadesUp()
{
    relay.setState(1, true);

    setTimeout(function () {
        relay.setState(1, false);
    }, 1000);
}

function ShadesDown()
{
    relay.setState(2, true);

    setTimeout(function () {
        relay.setState(2, false);
    }, 1000);
}

And by making an HTTP request like:

http://ipaddress:4400/shades_up

 

I can trigger Relay 1 on my device to turn on for one second, and then turn off, simulating the button press.

Because we use Ross Dashboard as our go-to production interface, I added Up/Down buttons to our FOH custom panels to send those commands to the relay server.

I then deployed the ShadeController Node JS project to a Raspberry Pi Zero, and put all the parts into my project box. I had our IT department make a DHCP reservation for the Pi so that it would always have the same IP address, making it easier to program around.

So, what does this really gain us, if the remote was already pretty easy to use?

1. We are no longer limited to RF range of the remote to control the shades. We can control it from anywhere on the network, including our control rooms which are located far away from the receiving end of the RF controller for the shades.
2. We can use the URLs in the ShadeController program as hooks in other projects to control the shades through automation. Time for the service to start? Just run the appropriate light cue on the light board and it fires a network midi command to a server that then relays the HTTP request needed.

Overall, this was a fairly inexpensive project.

• Raspberry Pi Zero W ($10): https://www.raspberrypi.org/products/raspberry-pi-zero-w/
• USB Relay ($12): https://www.amazon.com/KNACRO-SRD-05VDC-SL-C-Module-control-intelligent/dp/B071XHF67G
• Project Box ($8): https://www.amazon.com/gp/product/B0002BSRIO/

I ended up spending a little bit more because I bought a Raspberry Pi Zero W kit with a case and some other adapters that I didn’t already have, like a mini HDMI to HDMI connector, but if I end up buying another Zero, I’ll take the Pi case out of this project box and use it. I also bought a pack of project boxes for about $8 that were way too small and didn’t fit my parts, but I plan to use them for some other projects down the road.

I hope this gives you some ideas on ways you could automate or more efficiently control your non-networked equipment through the use of relays! I certainly learned a lot during this process and am looking forward to implementing it in other areas.