GPS-Based Lap Tracker

Live GPS lap tracking and visualization system using a Neo M8N GPS module + Python.

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Requirements

• Hardware

  • Neo M8N GPS Module
  • Microcontroller (e.g., Arduino)

• Python Libraries

  • serialpy
  • matplotlib
  • numpy

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Receiving and Parsing NMEA data

• The microcontroller being used to receive and parse gps data is an STM32F446RE
• USART1 was used to receive NMEA data and USART2 was used to print the latitudes and longitudes to the serial port.

STM Pin	GPS Pin	Function
PA10	TX	RX
PA9	RX	TX

• This code was referred to from micropeta. http://micropeta.com/video122

• *gpsParse(char strParse) -This function parses incoming NMEA GPS sentences ($GPGGA, $GPGLL, or $GPRMC) to extract latitude and longitude data. It converts the NMEA-format coordinates into decimal degrees using nmeaToDecimal() and sends the formatted result over UART.

  How it works:

  Checks which NMEA sentence type is received (GGA, GLL, or RMC).

  -Uses sscanf to extract latitude, longitude, and directional info. -Converts the raw NMEA latitude/longitude to standard decimal degrees. -Formats the result as a comma-separated string. -Transmits the final coordinates over UART2.

• nmeaToDecimal(float coordinate)

  • Converts a GPS coordinate from NMEA format (ddmm.mmmm) to standard decimal degrees (dd.dddddd).

Python Live Tracking Features

• GPS Data Acquisition
  High-accuracy GPS data is received using the NeoGPS library.

• Serial Communication
  Data is transmitted from the microcontroller and read via serialpy on the host PC.

• Real-Time Data Visualization
  GPS coordinates are plotted using matplotlib. The first lap defines the base track layout.

• Lap Detection and Timing
  A lap is considered complete when the current GPS location returns within a 0.00003° threshold of the start point.

• Live Tracking (Lap 2+)
  From the second lap onward, a moving location marker is shown. The base track remains constant.

• RPM Trail Visualization
  RPM is simulated and shown as a color-coded trail:

  • 🟢 Green: < 2000 RPM
  • 🟡 Yellow: 2000–4000 RPM
  • 🔴 Red: > 4000 RPM

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Core Functions

save_first_lap_trajectory()

• Saves latitude/longitude of the first lap into a .npy file.
• Returns the array for use in offset boundary drawing.

draw_virtual_start_line(lat, lon)

• Creates a vertical lime green start/finish line using the first GPS coordinate.
• Only drawn once at initialization.

update_lap_one()

• Called during lap 1.
• Simulates RPM and assigns a trail color.
• Plots GPS path in real-time.
• Updates blue current-location marker.
• Displays point count.

update_plot_lap_two_onwards()

• Called from lap 2 onwards.
• Applies RPM color logic.
• Loads saved first lap and draws offset track boundaries.
• Updates GPS trail and live position.
• Refreshes lap counter and timer.

check_lap_completion(lat, lon)

• Continuously checks proximity to the start line.
• Triggers when:
  • Enough points are recorded.
  • Start point is reached again.
• Actions:
  • Increments lap count.
  • Updates lap time.
  • Saves first lap (if applicable).
  • Clears old data to prep for the next lap.

Main Loop Logic

Continuously:

• Reads GPS data via Arduino serial (e.g., COM3).
• Parses GPS (lat, lon).
• Initializes start line.
• Appends valid coordinates.
• Calls:
  • update_lap_one() during lap 1.
  • update_plot_lap_two_onwards() for lap 2+.
• Handles cleanup on keyboard interrupt.

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Usage

** Hardware Setup**

• Connect your Neo M8N GPS module to your microcontroller (e.g., Arduino).
• Ensure the GPS module has a clear view of the sky for optimal signal.
• Upload your Arduino sketch that outputs GPS NMEA sentences via serial.