Here’s something fun from [Chad Kapper] over on HackMakeMod: Escape Room Lockbox with the Cheap Yellow Display. You may have heard of the “cheap yellow display” (CYD), so-called due to the board’s ...

Default value for maximum measurement distance is 4m, since HC-SR04 sensor can't measure reliably beyond that. However, if you are using another sensor or if you you don't care about distances larger ...