The web app compliment to https://github.com/sk0g/peripheral-emulator-bridge, allowing configuration of Serial connection, and emulation of a hanful of peripherals. See screenshots below.
Uses Web Serial APIs, so broken on Firefox when I was working on this.
Written using Svelte, JavaScript, and lots of spaghetti. Definitely not much of a frontend developer, but Svelte was amazing for productivity!
Ultrasonic sensor, where GPIO 6 is the expected trigger input pin, and GPIO 21 is the output pulse pin.
The figure 5 formed on the emulated seven-segment display, by the input pins on the left -- with their states visible on the fly!