2 layers60 × 40 mm
SPECTRAL
VeeT23/SPECTRAL
Performance line following robot submitted to Southwork Robotics 2026
56 partsGPL-3.0
2 layers40 × 18 mm
Sensor module
VeeT23/SPECTRALPerformance line following robot submitted to Southwork Robotics 2026
- Size
- 40 × 18 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 20
- Nets
- 27
- Pads
- 114
- Tracks, vias
- 482, 44
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 31 Dec 2025
- Updated
- 18 Aug 2026
Overview
Sensor module 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 40 × 18 mm with 20 parts on 27 nets, routed with 482 tracks and 44 vias.
It is built around the SN74LV4051APWR-M, SMF05C and TCRT5000. Its parts include 4 resistors, 3 ICs, 2 capacitors and 1 connector. It belongs with the robots and motor control and sensors and measurement boards and the ESP32 boards of this library.
Main components
3
SN74LV4051APWR-M
-- Signal Switches, Multiplexers, Decoders ROHSTexas InstrumentsSignal Switches, Multiplexers, Decoders
SMF05C
SC-88-40℃~+125℃ 100W@8/20us 12.5V 5 5V 7.2V 70nA 80pF 8A@8/20us IEC 61000-4-2 TVS SC-88 ESD and Surge Protection (TVS/ESD) ROHSonsemiESD And Surge Protection (TVS/ESD)
TCRT5000
DIP-4-25℃~+85℃ 0.4V 1.25V 100mA 15mm 70V 950nm Phototransistor DIP-4 Reflective Optical Interrupters ROHSVishay IntertechnologyReflective Optical Interrupters
README
README.mdSPECTRAL
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
SPECTRAL/
├── firmware/
│ ├── common/
│ ├── control_station_firmware/
│ └── spectral_firmware/
├── hardware/
│ ├── main_board/
│ ├── power_module/
│ └── sensor_module/
├── .gitignore
└── README.mdConfiguration
| 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
Parts
20| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | TCRT5000 | OptoDevice:TCRT5000-MINI | T1, T2, T3, T4, T5, T6, T7, T8 |
| 3 | 4.7K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2, R3 |
| 2 | 0.1 uf | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C2 |
| 2 | SN74LV4051APWR | SN74LV4051APWR:PW16 | U1, U2 |
| 1 | 100 | Resistor_SMD:R_Array_Convex_4x0612 | RN1 |
| 1 | 56 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R4 |
| 1 | 6p-IDC | SM06B_GHS_TB:CONN_SM06B-GHS-TB_JST | J1 |
| 1 | R_Pack08 | RES_EXB2HV:RES_EXB2HV | RN2 |
| 1 | SMF05C | Package_TO_SOT_SMD:SOT-363_SC-70-6_Handsoldering | U3 |
Questions
How big is the Sensor module PCB?
It measures 40 × 18 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Sensor module use?
20 parts, built around the SN74LV4051APWR-M, SMF05C and TCRT5000. 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 Sensor module KiCad files?
From the VeeT23/SPECTRAL repository on GitHub, at the commit this page was made from: the board is hardware/sensor_module/sensor_module.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 Sensor module 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).
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