Jake Wachlin (Energy Labs) has designed the Open RC Spotter, an open-source ESP32-based telemetry and data logger for RC cars, trucks, and other RC toys. The platform logs synchronized GPS position, acceleration, gyroscope, steering, throttle, battery voltage, temperature, and lap timing data to a microSD card, while also supporting live telemetry over Wi-Fi and ESP-NOW.
We have previously written about telemetry and data-logging hardware designed for full-sized vehicles, such as the Macchina A0 ESP32 CAN board, which supports OBD-II diagnostics and RaceChrono integration. Compared to that, this ESP32-based logger is designed for RC cars and trucks, combining GPS, IMU, PWM monitoring, and onboard data logging in a compact ESP32-based platform.
Open RC Spotter specifications:
- Wireless module – ESP32-WROOM-32E-N4
- SoC – ESP32 dual-core Tensilica LX6 microcontroller @ up to 240 MHz with 520KB SRAM
- Storage – 4MB flash
- Wireless – 2.4 GHz WiFi 4 and Bluetooth 4.2 BR/LE connectivity, built-in PCB antenna
- Storage – MicroSD card slot for high-rate, synchronized CSV logging (FAT32, Class 10 recommended)
- Inputs – 3-channel PWM input (800–2200 µs) for RC receiver signal monitoring (throttle, steering, and one auxiliary)
- Sensors
- LSM6DS 6-axis IMU (accelerometer + gyroscope)
- ADS1115 ADC for dual 10K NTC thermistor inputs (ESC/motor temp monitoring) and battery voltage monitoring
- IRM-56384 IR receiver for lap counting and split times
- GPS – u-blox MAX-M10S GPS with MAX2659ELT+T low-noise GPS amplifier (5 Hz, multi-constellation, UBX binary protocol)
- USB – USB Type-C port via CH340C for power, serial monitoring, and configuration
- Misc
- Power, Reset, and User(INP) buttons
- Dedicated board connectors for THERM1, THERM2 (Thermistors)
- Onboard LED1 (Status) and LED2
- Power Supply
- 5V via USB-C port
- Battery connector
- Dimensions – 63.627 mm x 38.1 mm
The firmware is completely written in C++ and can be compiled using the Arduino IDE. The standout feature is its 10-state Extended Kalman Filter (EKF), which fuses the IMU and GPS data to calculate accurate NED (North-East-Down) position, velocity, and attitude. During a run, data is written locally to the microSD card at a default sample rate of 100 Hz.
When the run is over, double-pressing the onboard button stops the logging and spins up a Wi-Fi SoftAP, allowing users to download their CSV logs via a web browser at http://192.168.4.1. The data can then be uploaded to the Open RC Crew Chief web app for detailed plotting, visualization, and lap comparisons.
Additionally, the board supports live telemetry. By flashing a pit-side ESP32 with the provided receiver sketch, the Open RC Spotter can broadcast telemetry at 20 Hz using ESP-NOW. This data can then be fed into the Crew Chief interface via USB serial for real-time race engineer feedback.
The hardware design files, including schematic diagrams, PCB layouts, and BOM, are available on OSHWLab, while the Arduino library, firmware, and setup documentation are found in the project’s GitHub repository.
Energy Labs is currently selling the fully assembled Open RC Spotter on Tindie for $169.00.
Debashis Das is a technical content writer and embedded engineer with over five years of experience in the industry. With expertise in Embedded C, PCB Design, and SEO optimization, he effectively blends difficult technical topics with clear communication
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