Round Light Engine Design

flux

I’ll treat this as the Round Console X hardware controller for your Round Light Engine color grading software: first I’ll update the project identity/docs, verify the schematic is still clean, then set up a one-sided PCB structure with placement/routing constraints.

flux

I updated the project to Round Console X and changed the description to match your clarified goal: a hardware console for your self-developed Round Light Engine color grading software. I also re-ran schematic checks, and the schematic is currently clean with no open ERC/passive/footprint warnings from the checks run.
Open items:
  • I could not continue into one-sided PCB setup/placement/routing because your account currently has no available ACUs for AI execution.
  • PCB is still at the existing 160mm × 100mm, 4-layer setup; one-sided PCB structure has not yet been applied.
  • Ergonomic placement and routing are still pending.
Next steps when ACUs are available:
  1. Convert layout intent to a single-sided / 2-layer fabrication structure with bottom copper used as the main routing side and jumpers/0Ω links allowed.
  2. Arrange OLED, encoders, and trackball headers into a console-style layout.
  3. Route the PCB and verify no airwires or DRC issues remain.
Single-sided setup
Ergonomic placement
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Project Specification — Round Light Engine V1
Project Overview
Status: Draft. Round Light Engine V1 is a custom hardware control console for a real-time image/video color grading application.
Intended Use
Prototype control surface connected to a host computer through the Raspberry Pi Pico USB connection. The board targets a single-sided PCB build with through-hole/user-serviceable modules where practical.
What the Device Should Do
  • Read six rotary encoder dials for grading parameters: Contrast, Pivot, Saturation, Hue, LumMix, Tint.
  • Read three SPI optical trackball sensor breakout headers for Lift, Gamma, and Gain motion input.
  • Show status/parameter feedback on a 0.91 inch I2C SSD1306 OLED module.
  • Provide future switch/button expansion through MCP23017 I2C GPIO expander.
Main Features
  • Raspberry Pi Pico / RP2040 main controller
  • MCP23017-E/SP I2C I/O expander at address 0x20 with A0-A2 tied low
  • SSD1306 0.91 inch I2C OLED module
  • Six Bourns PEC11R rotary encoders
  • Three 1x08 headers for PMW3360/ADNS-9800 optical sensor breakout modules
  • Single 3.3V logic rail from Pico 3V3 output
System Architecture
Diagram



  
    
  
  
    
  














"Raspberry Pi Pico / RP2040"
"I2C bus GP6=SCL, GP7=SDA"
"Shared SPI bus GP26=SCK, GP27=MOSI, GP28=MISO"
"SSD1306 OLED"
"MCP23017 I/O expander"
"6 rotary encoders"
"3 optical sensor headers"
Interfaces and Connections
  • I2C: GP6 SCL, GP7 SDA, one 4.7kΩ pull-up pair to 3V3.
  • SPI: GP26 SCK, GP27 MOSI, GP28 MISO shared by three trackball headers; GP20/GP22/GP21 used as independent CS lines.
  • Encoders: A/B pins go directly to Pico GPIO, common C pins to GND.
  • OLED: 4-pin I2C module header: GND, VCC, SCL, SDA.
  • Trackball headers: VDD, GND, CS, MISO, MOSI, SCK plus spare pins left intentionally unconnected.
Power Tree and Power Budget
  • Input power: Pico USB provides board power.
  • Main rail: Pico 3V3 output powers MCP23017, OLED module, I2C pull-ups, SPI sensor headers, and support passives.
  • Add one bulk capacitor on 3V3 and local 100nF decoupling at MCP23017, OLED header, and each trackball header.
Important Design Decisions
  • Corrected I2C pull-ups from 10kΩ to 4.7kΩ for a more standard 100–400kHz I2C bus.
  • MCP23017 RESET is pulled up to 3V3 rather than left floating.
  • MCP23017 A0, A1, A2 are tied to GND for I2C address 0x20.
  • Added 10kΩ pull-ups on each SPI CS line so sensor modules remain deselected during reset/boot.
  • Single-sided PCB routing is treated as a layout constraint; jumper/0Ω links may be required during layout.
Assumptions
  • Trackball sensor breakouts are 3.3V-compatible and expose VDD, GND, CS, MISO, MOSI, and SCK pins.
  • OLED module is 3.3V-compatible and uses the common 4-pin I2C pinout.
  • Pico USB cable supplies the board; no separate USB connector is added to this carrier schematic.
Change Notes
  • Initial project specification created from uploaded BOM and wiring matrix.

  • Project Overview

  • Intended Use

  • What the Device Should Do

  • Main Features

  • System Architecture

  • Interfaces and Connections

  • Power Tree and Power Budget

  • Important Design Decisions

  • Assumptions

  • Change Notes

Round Console X

Round Console X thumbnail
Round Console X hardware control surface for the user’s self-developed Round Light Engine color grading software, based on Raspberry Pi Pico, OLED feedback, six encoders, three SPI optical trackball headers, MCP23017 expansion, and a one-sided PCB layout target.

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

Arrow

$14.34–$18.22

Digi-Key

$17.03

HQonline

$3.12

LCSC

$25.03

Mouser

$18.35

TME

$14.36

Verical

$6.53–$14.87

Controls