ESP32 Kart Telemetry System

A distributed telemetry and datalogging system for open-track go-karts. The project uses a helmet-mounted logger node paired with an ESP32 display dashboard over ESP-NOW.

System Architecture

The current firmware supports two primary targets:

1. Helmet Logger Node

   • Board: Seeed XIAO ESP32S3
   • Role: GPS acquisition, battery monitoring, audio cues, error logging, and telemetry broadcast.
   • Features:
     • GPS from u-blox (default) or ATGM336.
     • Battery percentage sampling.
     • Audio playback through I2S.
     • Helmet error log capture and transfer.
     • Telemetry packet composition using GPS, IMU feedback, and battery state.

2. Display Dashboard Node

   • Board: ESP32-3248S035C
   • Role: UI dashboard, SD logging, and optional IMU-based speed filtering.
   • Features:
     • Receives telemetry from the helmet logger over ESP-NOW.
     • Displays speed, G-force, GPS satellite count, and helmet battery state.
     • Logs telemetry to SD card.
     • Sends IMU feedback to the helmet logger when ENABLE_IMU is enabled.
     • Receives helmet error logs and writes them to SD.

Build targets in platformio.ini

• env:logger — helmet logger firmware (main_logger.cpp)
• env:display — display dashboard firmware (main_display.cpp)

Key Technical Features

• ESP-NOW telemetry link between the helmet logger and display dashboard.
• Modular GPS provider abstraction in GpsManager.
• fix_stride.py prebuild patch for SquareLine Studio LVGL 9 image exports.
• Helmet error log transport from logger to display via structured ESP-NOW messages.
• Optional wheel IMU support on the display dashboard to improve speed filtering and live telemetry.
• SPI bus arbitration for display rendering and SD card access using a mutex.

Hardware Requirements

• ESP32-3248S035C display board
• Seeed Studio XIAO ESP32S3 logger board
• GPS module (u-blox or ATGM336)
• Optional MPU6050 IMU for wheel/dashboard module
• I2S audio amplifier and speaker
• SD card formatted FAT32 for dashboard logging

Software Dependencies

Built with PlatformIO.

Libraries used by the current configuration:

• lvgl/lvgl (v9.x)
• rzeldent/esp32_smartdisplay
• mikalhart/TinyGPSPlus
• ElectronicCats/MPU6050
• espressif/esp32-audioI2S

GPS Providers

The logger firmware supports two GPS providers through GpsManager.

• u-blox provider (default)
  • No additional build flag required.
  • Update interval: 200ms (5Hz).
• ATGM336 provider
  • Enable with -D GPS_PROVIDER_ATGM336.
  • Update interval: 100ms (10Hz).

Changing the GPS provider

In platformio.ini, under [env:logger] -> build_flags:

• Comment out -D USE_FAKE_GPS to use real GPS hardware.
• Uncomment -D GPS_PROVIDER_ATGM336 to select the ATGM336 provider.
• Leave -D GPS_PROVIDER_ATGM336 commented to use u-blox.

Telemetry timing is derived from GpsManager::getUpdateIntervalMs(), so the logger loop cadence automatically follows the selected GPS provider.

Setup & Installation

1. Clone this repository.
2. Open it in VSCode with PlatformIO.
3. Edit the UI using the SquareLine Studio project files in UIDesign/.
4. Export the UI to /lib/ui/ and let fix_stride.py patch LVGL image metadata during build.
5. Flash the selected firmware:
   • pio run -e logger -t upload
   • pio run -e display -t upload

ESP-NOW Protocol

The telemetry protocol is defined in lib/Shared/EspNowProtocol.h.

• MSG_TELEMETRY — helmet logger broadcast.
• MSG_IMU_FEEDBACK — dashboard IMU uplink to logger.
• MSG_ERROR_LOG_START, MSG_ERROR_LOG_LINE, MSG_ERROR_LOG_END — helmet error log transfer.

The current codebase uses ESPNOW_CHANNEL 1 for all packet exchanges.

Design files

Design files are included under the hardware/ folder.

3D Models

I've used Fusion to design 3D models for the custom enclosures and mounts. These are located in hardware/3d_models/ and exported as .f3d and .3mf files. You can open and modify these in Fusion or any compatible 3D modeling software.

PCB Designs

The PCB design is created in KiCad and located in the hardware/pcb/ folder. The helmet logger PCB is designed to fit within the existing enclosure on the MT Stinger 2 helmet (this enclosure was built to fit Universal Communication Systems hardware and can be found on other helmets).

Visual Reference

The repository includes renderings and module photos in the images/ folder.

Notes

• The display firmware is responsible for UI rendering and SD logging.
• The logger firmware is responsible for GPS, battery, audio, and helmet error captures.
• USE_FAKE_GPS is available for development without real GPS hardware.