Have you ever had to run up to the store right before your spouse or kids were supposed to get home, and felt the need to leave them a message? Like most people, you probably just scribbled a note on the back of an old receipt. You tossed it on the table and simply crossed your fingers and hoped that they’d see it before getting too worried. They, of course, didn’t see it and called you in a panic just as you were trying to swipe your credit card. A far better solution is to build this voice-controlled scrolling message board designed by Rob Latour.
This display resembles the kind you would have seen showing departure times in an airport terminal or train station during the ‘90s, before they were replaced by large flat screen TVs. It’s an LED matrix display with a very wide aspect ratio — perfect for showing a scrolling sentence or two. In this case, it is made up of three 4-in-1 MAX7219 dot matrix modules. Those are constructed from four 8x8 LED matrix modules, so the total resolution of the display is 96x8 pixels. Those modules are made for working with boards like an Arduino Uno, but Latour's hardware makes it far easier to set the current message.
The most important piece of hardware, other than the LED matrix modules themselves, is an ESP32 board. That board was chosen because it has built-in WiFi (and Bluetooth) capabilities that make it ideal for IoT projects. That’s perfect, because it can be integrated with any smart home device running Google Assistant. That’s how the voice control works for this project. Google Assistant accepts the voice command, then that’s sent to your IFTTT account via PushBullet, and finally an IFTTT applet sets the text on the scrolling message board. A 3D-printed enclosure and a red acrylic cover make for a nice enclosure. If you want a better way to leave messages than hastily-scribbled notes, this is a great choice.