2 layers100 × 100 mm Controller, the printed circuit board in 3D

Controller

Firmware and PCB files for an ESP32-S3 sim-racing button box with five rotary encoders, capacitive touch on encoder/buttons, two ST7789 displays, MCP23017 button/LED expansion, MPR121 touch sensing, WS2812 status LEDs…

Open in PCBKit

Size: 100 × 100 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 66
Nets: 103
Pads: 301
Tracks, vias: 987, 65
Routed: Yes
KiCad: KiCad 9.0 (file 20241229)
Created: 6 Jul 2026
Updated: 6 Jul 2026

Overview

Controller is an open-source printed circuit board by Hartmannlight, from the Hartmannlight/Buttonbox repository on GitHub. It is a 2-layer board of 100 × 100 mm with 66 parts on 103 nets, routed with 987 tracks and 65 vias.

It is built around the ESP32-S3-DEVKITC-1-N8, DS18B20 and MPR121QR2, with the MCP23017-E/SS and PN2222A among its other parts. Its parts include 21 resistors, 7 capacitors, 6 transistors, 5 ICs and 5 switches. It belongs with the ESP32 boards of this library.

Main components

README

README.md

KLX ButtonBox

Repository layout

text

src/
  app/        Firmware application helpers and diagnostics
  config/     Hardware pinout and device addresses
  domain/     Hardware-independent events and device state
  hal/        Arduino/driver-facing hardware adapters
pcb/
  ButtonBox/  Encoder/display board KiCad project
  Controller/ Controller board KiCad project
scratch/      One-off hardware analysis scripts

Firmware status

The firmware is currently a hardware diagnostic build, not a finished sim-racing HID profile. It boots the ESP32-S3, scans I2C, initializes both displays, reads encoders/buttons/touch, drives diagnostic LEDs, and renders current state on the displays.

Known hardware items still need bench verification:

FFC orientation and all 30 continuity mappings.
MPR121 address and touch thresholds for the real metal controls.
MCP23017 button/LED mapping against the assembled PCB.
GPIO0 boot behavior with DS2 backlight.
Buzzer circuit. Firmware intentionally keeps it muted until the hardware is verified.

Build

Install PlatformIO, then run:

powershell

platformio run

Upload to the connected ESP32-S3:

powershell

platformio run --target upload

Open the serial monitor:

powershell

platformio device monitor

Serial speed is 115200.

Hardware notes

The authoritative pin constants live in src/config/HardwareConfig.hpp. The longer hardware handover is in KLX_ButtonBox_Firmware_Handover.md; treat it as a verification log and update it when a measurement on the real device contradicts an assumption.

Parts

Qty	Value	Footprint	References
9	10k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R8, R13, R14, R15, R16, R17, R18, R20, R21
6	100 nF	Capacitor_THT:C_Disc_D3.0mm_W2.0mm_P2.50mm	C1, C2, C3, C4, C5, C7
6	1k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R1, R3, R4, R5, R6, R7
6	PN2222A	Package_TO_SOT_THT:TO-92_Inline	Q1, Q2, Q3, Q4, Q5, Q6
5	SW_MEC_5G_2LED_TOUCH	Connector_Wire:SolderWire-0.5sqmm_1x05_P4.6mm_D0.9mm_OD2.1mm_Relief	SW1, SW2, SW3, SW4, SW5
2	TestPoint	TestPoint:TestPoint_Pad_1.0x1.0mm	TP1, TP2
1	1.5k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R9
1	150	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R11
1	220	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R12
1	3.3V PWR	LED_SMD:LED_Foshan-NTD3528_3.5x2.8mm	D2
1	330	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R19
1	4.7k	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R2
1	5V PWR	LED_SMD:LED_Foshan-NTD3528_3.5x2.8mm	D1
1	680	Resistor_THT:R_Axial_DIN0207_L6.3mm_D2.5mm_P10.16mm_Horizontal	R10
1	A0	Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm	JP6
1	A1	Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm	JP5
1	A2	Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm	JP4
1	ADDR VCC/GND	Jumper:SolderJumper-3_P1.3mm_Open_Pad1.0x1.5mm_NumberLabels	JP2
1	Buzzer	Buzzer_Beeper:Buzzer_TDK_PS1240P02BT_D12.2mm_H6.5mm	BZ1
1	C_Polarized	Capacitor_THT:CP_Radial_D5.0mm_P2.50mm	C6
1	Conn_01x30_MountingPin	Connector_FFC-FPC:Molex_200528-0300_1x30-1MP_P1.00mm_Horizontal	J4
1	DS18B20	Package_TO_SOT_THT:TO-92_Inline	U2
1	ESP32-S3-DevKitC	PCM_Espressif:ESP32-S3-DevKitC	U1
1	I2C	TestPoint:TestPoint_2Pads_Pitch2.54mm_Drill0.8mm	J3
1	IRQ Pullup	Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm	JP7
1	MCP23017	Aliexpress:MCP23017-Breakout	U6
1	MPR121QR2	Aliexpress:MPR121QR2-Breakout	U3
1	Power	Connector_JST:JST_XA_B02B-XASK-1_1x02_P2.50mm_Vertical	J2
1	SCL Pullup	Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm	JP9
1	SDA Pullup	Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm	JP8
1	Status	LED_SMD:LED_Foshan-NTD3528_3.5x2.8mm	D3
1	Use PN222 5V	Jumper:SolderJumper-3_P1.3mm_Bridged12_RoundedPad1.0x1.5mm_NumberLabels	JP1
1	VREF on 3.3V	Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm	JP3
1	~	Connector_JST:JST_XA_B03B-XASK-1_1x03_P2.50mm_Vertical	U4
1	~	Aliexpress:ESP32-JTAG	JTAG

The 63 most common of 66 parts.

Questions

How big is the Controller PCB?

It measures 100 × 100 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Controller use?

66 parts, built around the ESP32-S3-DEVKITC-1-N8, DS18B20, MPR121QR2 and MCP23017-E/SS. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the Controller KiCad files?

From the Hartmannlight/Buttonbox repository on GitHub, at the commit this page was made from: the board is pcb/Controller/Controller.kicad_pcb and its schematic pcb/ButtonBox/ButtonBox.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Controller design in my own project?

Its repository states no licence, so its author keeps all rights: ask Hartmannlight before reusing the design.

Category and platform

ESP32

Project files

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A picture

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A picture that opens the board, for a README

[![Controller](https://pcbkit.io/embed/boards/hartmannlight-buttonbox-controller.jpg?size=s)](https://pcbkit.io/boards/hartmannlight-buttonbox-controller)

Source

Repository: Hartmannlight/Buttonbox
Board file: pcb/Controller/Controller.kicad_pcb
Commit: 2543d5e
Licence: Not stated

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