The UNO Scrubber — Professional Timeline Controller

Mac + Arduino Uno | by roB0Ting MakerWorld

Find this project on MakerWorld: Arduino Uno Knob Macro Pad

Turn your dusty Arduino Uno into a professional video editing controller. Most DIY macro pads require you to buy specific "Pro Micro" boards to work as a keyboard. This project is different — it uses the standard Arduino Uno most makers already have! It bridges the Uno to your Mac using a lightweight, zero-latency Python script that auto-detects the device on any USB port.

Remix Challenge: This is a fully functional V1, but the current case design requires the Arduino to sit externally (connected by wires reaching out of the box). This project is released under a CC BY-SA license — the community is encouraged to remix this enclosure to fit the Uno inside!

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Features

• Mode 1 (LED Off): Precision Scrubbing — Left/Right Arrow keys
• Mode 2 (LED Bright): Fast Scrubbing — Shift + Left/Right
• 4 Custom Macro Keys: Shift+N, S, Ripple Delete (Option+Del), and Mode Toggle
• Zero Latency: Custom buffer-flush logic for instant response
• Jitter-Free: Uses a "State Machine" to eliminate rotary encoder bounce

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Repository Structure

UNO-Scrubber/
├── firmware/
│   └── uno_scrubber/
│       └── uno_scrubber.ino   ← Upload this to your Arduino Uno
├── mac/
│   └── scrubber.py            ← Run this on your Mac
└── images/                    ← Build reference photos

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Bill of Materials (BOM)

Item	Part	Notes
1x Arduino Uno (Rev 3)	Elegoo Uno R3 (~$16)	High quality, reliable clone
1x KY-040 Rotary Encoder	DEVMO 2PCS KY-040	Standard module, comes with most Uno kits
4x Mechanical Switches	Gateron Brown Switches 10pcs (~$2)	Or any Cherry MX style switch
1x LED + Resistor	LED Resistor Kit 600Pcs	Any color LED + a 220Ω resistor
Wires	Elegoo 120pcs Multicolored Dupont Wire	See notes below
5x Flat Head Screws	6-32 Thread, 5/16" Long	Or use Super Glue / Hot Glue for the lid

Wire types needed:

• Male-to-Male: Solder one end to the switches, plug the other end into the Arduino
• Male-to-Female: Used for the Rotary Encoder (no soldering required on the encoder side)

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Step 1 — Print & Assemble the Case

1. Print: Main Case, Bottom Plate, and Knob (+ optional knob finger groove)
2. Insert: Snap the 4 switches into the Top Plate from the top
3. Mount: Slide the Rotary Encoder in from the bottom and glue/screw it on
4. Optional: Glue the finger groove onto the top of the knob

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Step 2 — Wiring (The "Common Ground" Method)

Since the Arduino sits outside the case, wires need to be long enough to reach out.

A. The Switches (Male-to-Male Wires)

For the switches, use spare resistor legs as short jumper wires for soldering:

1. Take spare resistors from your LED kit — snip off one leg per switch
2. Use these legs to make short jumper wires (you're using the metal, not the resistance)
3. Solder the cut end to one pin of each switch, keeping the other pin open for the Arduino

Ground Chain: Solder a wire connecting one pin from every switch together. Run a final wire from this chain to a GND pin on the Arduino.

Signal Wires: Solder a separate male-male wire to the remaining pin of each switch.

Switch Pinout

Switch Function	Arduino Pin
Mode Toggle	Pin 5
Shift + N	Pin 6
S (Select)	Pin 7
Option + Delete	Pin 8

B. The Mode Indicator LED

The Mode Toggle key glows when High Speed Mode is active.

• Preparation: Solder your 220Ω resistor to the long leg (+) of the LED
• Mounting: Apply hot glue to the bottom body of the Mode Toggle switch (Pin 5). Press the LED into the glue so it shines up into the keycap
• Long Leg (+): Connect the resistor end to Pin 9
• Short Leg (−): Connect to GND

LED State	Description
	Mode 1 — Precision Scrub
	Mode 2 — Fast Scrub

C. The Rotary Encoder (Male-to-Female Wires)

Use Male-to-Female wires — plug the Female end onto the encoder pins, run the Male end to the Arduino.

Encoder Pin	Arduino Pin
CLK	Pin 2
DT	Pin 3
SW (Button)	Pin 4
+ (VCC)	5V
GND	GND

Tip: Label your wires — they can get jumbled quickly!

D. Close It Up

1. Bundle the wires carefully
2. Screw the bottom lid on (or dab hot glue on the corners)
3. Press the 3D printed knob onto the encoder shaft (tolerances may be tight)

Master Wiring Chart

Component	Pin / Leg	Connection	Wire Type
Rotary Encoder CLK	—	Pin 2	Male-to-Female
Rotary Encoder DT	—	Pin 3	Male-to-Female
Rotary Encoder SW (Button)	—	Pin 4	Male-to-Female
Rotary Encoder + (VCC)	—	5V	Male-to-Female
Rotary Encoder GND	—	GND	Male-to-Female
Switch 1 (Mode)	Signal Pin A	Pin 5	Male-to-Male
Switch 2 (Shift+N)	Signal Pin A	Pin 6	Male-to-Male
Switch 3 (S)	Signal Pin A	Pin 7	Male-to-Male
Switch 4 (Opt+Del)	Signal Pin A	Pin 8	Male-to-Male
All Switches	GND Pin B	GND Daisy-Chain	Male-to-Male
LED Long Leg (+)	—	Pin 9 (via 220Ω Resistor)	Soldered
LED Short Leg (−)	—	GND	Soldered

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Step 3 — Upload the Arduino Firmware

1. Download and install the Arduino IDE
2. Plug in your Uno. Select your port in Tools > Port
3. Open firmware/uno_scrubber/uno_scrubber.ino in the Arduino IDE
4. Click Upload (the arrow icon)

The firmware is in firmware/uno_scrubber/uno_scrubber.ino.

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Step 4 — Mac Setup

The Arduino Uno is not a native keyboard — a small Python script bridges it to your Mac.

A. Find Your Username

1. Open Terminal (Cmd+Space → type "Terminal")
2. Type whoami and press Enter
3. Note the name shown (e.g., johnsmith)

B. Install Required Python Libraries

Paste this into Terminal and press Enter:

pip3 install pyserial pyautogui --break-system-packages

If that fails, try:

pip3 install pyserial pyautogui

If it asks for a password, type your Mac login password — you won't see the letters, just press Enter.

C. Save the Script

1. Open TextEdit
2. In the menu bar: Format > Make Plain Text ⚠️ Do NOT skip this step
3. Paste the contents of mac/scrubber.py into the document
4. Save as scrubber.py inside your Documents folder

⚠️ Press Cmd+I on the file to confirm the name is exactly scrubber.py and not scrubber.py.txt

D. Grant Accessibility Permissions

1. Go to System Settings > Privacy & Security > Accessibility
2. Click + and add Terminal
3. Toggle it ON

⚠️ If you've already created the Automator app (next step), add the app instead of Terminal.

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Step 5 — Auto-Start on Login

Make the scrubber launch automatically when your Mac boots.

1. Open Automator (Cmd+Space → type "Automator")
2. Select Application
3. Search for "Run Shell Script" and drag it to the main window
4. Paste the following command — replace [YOUR_USERNAME] with the name from Step 4A:

Try this first (Standard Python):

/usr/bin/python3 /Users/[YOUR_USERNAME]/Documents/scrubber.py

If the above doesn't work (Homebrew Python):

/opt/homebrew/bin/python3 /Users/[YOUR_USERNAME]/Documents/scrubber.py

5. Click the Run (Play) button to test — if the knob works, you're good!
6. File > Save the app as ScrubberApp in your Applications folder
7. Go to System Settings > General > Login Items and add ScrubberApp

⚠️ Now that you have an Application, update Accessibility permissions (Step 4D) to point to ScrubberApp instead of Terminal.

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You're Done!

Your Uno Scrubber is now part of your editing desk.

Note: If you unplug the scrubber while your Mac is running, you'll get an error message. Plugging it back in won't auto-reconnect — just reopen the ScrubberApp and wait a few seconds.

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License

Released under CC BY-SA. Build it, remix it, share it!

This is an experimental V1 project. If you run into issues or have suggestions, open an issue or leave a comment.