2 layers60 × 40 mm SPECTRAL, the printed circuit board in 3D

SPECTRAL

Performance line following robot submitted to Southwork Robotics 2026

Size: 60 × 40 mm
Copper layers: 2
Thickness: 1.6 mm
Parts: 56
Nets: 50
Pads: 225
Tracks, vias: 392, 67
Pours: 1
Routed: Yes
KiCad: KiCad 9.0 (file 20241229)
Created: 31 Dec 2025
Updated: 18 Aug 2026

Overview

SPECTRAL is an open-source printed circuit board by VeeT23, from the VeeT23/SPECTRAL repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 60 × 40 mm with 56 parts on 50 nets, routed with 392 tracks and 67 vias.

It is built around the ATA6561-GAQW-N and BSS138. Its parts include 18 resistors, 13 capacitors, 12 connectors, 2 ICs and 2 transistors. It belongs with the robots and motor control boards and the ESP32 boards of this library.

Main components

README

README.md

SPECTRAL

Short description of the embedded system and what it does.

Overview

SPECTRAL is a performance line following robot

Hardware

Main Components

Component	Part Number	Description
MCU	ESP32-WROOM-32UE	Main microcontroller
Orientation Sensor	BNO055	9-DoF absolute orientation sensor with accelerometer, gyroscope, and magnetometer
Motor Controller	ODrive Micro	100 W BLDC motor controller
Motor	Flash Hobby D4215	4215 650 KV BLDC motor, 3S–6S
CAN Transceiver	ATA6561	CAN transceiver for motor controller communication

Pinout

Pin Definitions

GPIO	Function	Interface	Notes
16	A0	Sensor Address	Sensor address select
17	A1	Sensor Address	Sensor address select
18	A2	Sensor Address	Sensor address select
32	S0	Sensor Output	Sensor output
33	S1	Sensor Output	Sensor output
34	S2	Sensor Output	Sensor output
35	S3	Sensor Output	Sensor output
39	S4	Sensor Output	Sensor output
19	CAN_STBY	CAN	CAN transceiver standby control
4	CAN_RX	CAN	CAN receive
5	CAN_TX	CAN	CAN transmit
22	SDA	I2C	I2C data
21	SCL	I2C	I2C clock
25	BUZZER	GPIO	Buzzer control
26	NEOPIXEL	GPIO	Exposed on board; currently unused
27	FAN_PWM	PWM	Exposed on board; currently unused

Software

Toolchain

Platform: Espressif32
MCU: ESP32-WROOM-32UE
Framework: Arduino
Build System: PlatformIO
IDE: Visual Studio Code + PlatformIO

Repository Structure

text

SPECTRAL/
├── firmware/
│   ├── common/
│   ├── control_station_firmware/
│   └── spectral_firmware/
├── hardware/
│   ├── main_board/
│   ├── power_module/
│   └── sensor_module/
├── .gitignore
└── README.md

Configuration

Parameter	Value	Description
Control Frequency	1000 Hz	Main control loop frequency
Display Update Period	40 ms	Period between display updates
Wheel Spacing	104 mm	Distance between drive wheels
Wheel Diameter	60 mm	Drive wheel diameter
Wheel Circumference	0.1885 m	Calculated wheel circumference
Line Following Kp	1.0	Proportional gain
Line Following Ki	0.01	Integral gain
Line Following Kd	0.01	Derivative gain
Number of Sensor Modules	5	Number of IR sensor modules
Sensors per Module	8	Number of sensors on each module
Total IR Sensors	40	Total number of IR sensors
IR Threshold	2000	Sensor threshold used for line detection
Controller MAC	`D8:3B:DA:46:57:80`	MAC address of the remote controller
Radio RX Timeout	1000 ms	Maximum time without receiving controller data
Telemetry Frequency	120 Hz	Telemetry transmission frequency
Radio Debug	Disabled	Enables/disables radio debug output
CAN Bitrate	500 kbit/s	CAN bus communication speed
CAN TX Timeout	40 ms	Maximum time to wait for CAN transmission
Serial Baud Rate	115200	Serial communication baud rate
ODrive Heartbeat Timeout	200 ms	Maximum time without receiving an ODrive heartbeat
Motors Enabled	Yes	Enables motor operation

ODrive Commands

The following CAN command IDs are used to communicate with the ODrive motor controller:

Command	CAN ID	Description
Heartbeat	`0x01`	ODrive heartbeat
Emergency Stop	`0x02`	Trigger emergency stop
Set Axis State	`0x07`	Change ODrive axis state
Get Encoder Estimate	`0x09`	Request encoder position/velocity estimate
Set Input Velocity	`0x0D`	Set motor velocity command
Clear Errors	`0x18`	Clear ODrive errors

ODrive Axis States

State	Value	Description
Idle	`1`	Motor disabled / idle
Closed Loop	`8`	Motor enabled for closed-loop control

Power

Spectral uses a 450 mAh 3s 75C lipo Running power is unknown however the circuit supports up to 10A continous. Idle power is measured to be ~140ma

WARNING: AS IT STANDS CURRENTLY, SPECTRAL LACKS OVER DISCHARGE PROTECTION, MONITOR BATTERY VOLTAGE BETWEEN RUNS TO AVOID DAMAGE TO THE BATTERY

Communication

UART - Serial debugging/flashing
I2C - Display screen
CAN - Motor controllers
ESP-NOW - Base station communication

Known Issues

Dynamic velocity control has no smoothing between setpoints
Power module lacks battery monitoring for undervoltage

Future Work

This project is closed, however I will add documentation/clean up issues on request.

License

This project is licensed under the GNU GENERAL PUBLIC LICENSE.

Author

Veronica Tobias

GitHub

Parts

Qty	Value	Footprint	References
9	100	Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder	R3, R4, R5, R6, R7, R15, R16, R17, R18
9	4.7K	Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder	R1, R2, R8, R9, R10, R11, R12, R13, R14
5	1nf	Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder	C3, C4, C5, C6, C7
3	0.1uf	Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder	C1, C8, C10
3	10uf	Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder	C2, C9, C11
2	100uf	Capacitor_THT:CP_Radial_D5.0mm_P2.00mm	C12, C13
2	BSS138	Package_TO_SOT_SMD:SOT-23	Q1, Q4
1	3V3	TestPoint:TestPoint_Pad_D2.0mm	TP3
1	5V	TestPoint:TestPoint_Pad_D2.0mm	TP4
1	ATA6561-GAQW-N	Package_SO:SOIC-8_3.9x4.9mm_P1.27mm	U2
1	BOOT	SW_PTS636_CNK:SW_PTS636_CNK	SW1
1	BOOT	TestPoint:TestPoint_Pad_D2.0mm	TP1
1	Buzzer	PS1240P02CT3:XDCR_PS1240P02CT3	BZ1
1	CAN	Connector_JST:JST_GH_SM04B-GHS-TB_1x04-1MP_P1.25mm_Horizontal	J6
1	EN	TestPoint:TestPoint_Pad_D2.0mm	TP2
1	ESP32-WROOM-32UE_M113EH6400UH3Q0_	RF_Module:ESP32-WROOM-32UE	U1
1	GND	TestPoint:TestPoint_Keystone_5005-5009_Compact	TP5
1	IMU	Connector_JST:JST_GH_SM04B-GHS-TB_1x04-1MP_P1.25mm_Horizontal	J7
1	NEOPIXEL	Connector_JST:JST_GH_SM03B-GHS-TB_1x03-1MP_P1.25mm_Horizontal	J12
1	OLED	Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical	J8
1	PWM	Connector_JST:JST_GH_SM03B-GHS-TB_1x03-1MP_P1.25mm_Horizontal	J11
1	Power	Connector_JST:JST_GH_BM04B-GHS-TBT_1x04-1MP_P1.25mm_Vertical	J9
1	RED	LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder	D1
1	RESET	SW_PTS636_CNK:SW_PTS636_CNK	SW2
1	Sensor 1	Connector_JST:JST_GH_SM06B-GHS-TB_1x06-1MP_P1.25mm_Horizontal	J1
1	Sensor 2	Connector_JST:JST_GH_SM06B-GHS-TB_1x06-1MP_P1.25mm_Horizontal	J2
1	Sensor 3	Connector_JST:JST_GH_SM06B-GHS-TB_1x06-1MP_P1.25mm_Horizontal	J3
1	Sensor 4	Connector_JST:JST_GH_SM06B-GHS-TB_1x06-1MP_P1.25mm_Horizontal	J4
1	Sensor 5	Connector_JST:JST_GH_SM06B-GHS-TB_1x06-1MP_P1.25mm_Horizontal	J5
1	UART	Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical	J10

Questions

How big is the SPECTRAL PCB?

It measures 60 × 40 mm and has 2 copper layers, 1.6 mm thick.

What parts does the SPECTRAL use?

56 parts, built around the ATA6561-GAQW-N and BSS138. 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 SPECTRAL KiCad files?

From the VeeT23/SPECTRAL repository on GitHub, at the commit this page was made from: the board is hardware/main_board/main.kicad_pcb and its schematic hardware/main_board/main.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the SPECTRAL design in my own project?

Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).

Category and platform

Robots and motor control ESP32

Topics

esp32

Project files

Show this board on your page

A live frame, for any web page

<iframe src="https://pcbkit.io/embed/boards/veet23-spectral-main" title="SPECTRAL in PCBKit" width="100%" height="480" style="border:0;border-radius:12px" allow="fullscreen" loading="lazy"></iframe>

A picture

<img src="https://pcbkit.io/embed/boards/veet23-spectral-main.jpg" alt="SPECTRAL" width="1200" height="900">

A picture that opens the board, for a README

[![SPECTRAL](https://pcbkit.io/embed/boards/veet23-spectral-main.jpg?size=s)](https://pcbkit.io/boards/veet23-spectral-main)

Source

Repository: VeeT23/SPECTRAL
Board file: hardware/main_board/main.kicad_pcb
Commit: 85ace45
Licence: GPL-3.0

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