mwiemarc

Update on Nov 30, 2025: This Gist is nearly eight years old! These instructions worked back in 2018 for the Pi 3, but recent comments suggest that they may not be sufficient on more recent Pi models and newer versions of Raspberry Pi OS. Be advised.

Using a rotary encoder as a volume control

On my RetroPie machine I wanted a hardware volume knob — the games I play use a handful of emulators, and there's no unified software interface for controlling the volume. The speakers I got for my cabinet are great, but don't have their own hardware volume knob. So with a bunch of googling and trial and error, I figured out what I need to pull this off: a rotary encoder and a daemon that listens for the signals it sends.

Rotary encoder

Configuring the Digispark ATTINY85 board for Arduino IDE and upgrading the bootloader

Warning: this document has to be updated by pointing to https://github.com/SpenceKonde/ATTinyCore

This note describes the configuration of an ATtiny85 based microcontroller development board named Digispark and similar to the Arduino line. It is available in many online marketplaces for roughly 1 dollar (e.g., Ebay, Amazon, AliExpress) and is shipped fully assembled, including a V-USB interface (a software-only implementation of a low-speed USB device for Atmel's AVR microcontrollers). Coding is similar to Arduino: it uses the familiar Arduino IDE and is already provided with a ready-to-use bootloader (

Exposed headers

Service	SSL	status	Response Type	Allowed methods	Allowed headers

JavaScript GUI libraries

These libraries can be used to quickly create a GUI for configureable parameters using sliders, checkboxes, colors pickers etc

Tweakpane https://github.com/cocopon/tweakpane Demo: https://cocopon.github.io/tweakpane/
control-panel https://github.com/freeman-lab/control-panel
ControlKit https://github.com/automat/controlkit.js
guify https://github.com/colejd/guify Main site is down, here is the demo https://jons.website/projects/guify/index
oui https://github.com/wearekuva/oui
Palette.js https://github.com/lehni/palette.js

	/**
	* Resize the image to a new width and height using nearest neighbor algorithm.
	* To make the image scale proportionally,
	* use 0 as the value for the wide or high parameters.
	* For instance, to make the width of an image 150 pixels,
	* and change the height using the same proportion, use resize(150, 0).
	* Otherwise same usage as the regular resize().
	*
	* Note: Disproportionate resizing squashes "pixels" from squares to rectangles.
	* This works about 10 times slower than the regular resize.

	package main

	import (
	"fmt"
	"net"
	"os"
	"strings"
	)

	func main() {

	<header>
	<h1>Parallax Effect</h1>
	<p>Pure CSS // No JavaScript !</p>

	</header>

	/*
	A worklet for recording in sync with AudioContext.currentTime.

	More info about the API:
	https://developers.google.com/web/updates/2017/12/audio-worklet

	How to use:

	1. Serve this file from your server (e.g. put it in the "public" folder) as is.