Wireless Plotter

Overview

Data visualization is an important tool for drone debugging. In this project, you will learn how to transmit the drone’s flight data back to the computer via Wi-Fi and plot curves in real-time.

What You’ll Learn

• Wi-Fi communication
• UDP protocol
• Data visualization
• Python scripts

Materials Needed

Item	Quantity	Notes
ESP32 Drone	1	-
Computer	1	With Python + Matplotlib installed
plotter.py	1	Data visualization script

Step 1: Open the Project

Extract wifi_telemetry.zip and open with VS Code.

Step 2: Modify Data Sending Function

Open wifilink.c and find the wifilink_send_data function:

void wifilink_send_data(float altitude, float roll, float pitch, float yaw) {
  // 1. Package data in JSON format
  char buffer[256];
  sprintf(buffer, "{\"alt\":%.2f,\"roll\":%.2f,\"pitch\":%.2f,\"yaw\":%.2f}",
          altitude, roll, pitch, yaw);

  // 2. Send to computer via UDP
  struct sockaddr_in dest_addr;
  dest_addr.sin_family = AF_INET;
  dest_addr.sin_port = htons(8888);
  dest_addr.sin_addr.s_addr = inet_addr("192.168.4.2"); // Computer IP

  sendto(sock, buffer, strlen(buffer), 0,
         (struct sockaddr*)&dest_addr, sizeof(dest_addr));
}

Step 3: Compile and Flash

Compile and flash the code, power on the drone (it will create Wi-Fi hotspot: ESP-Drone).

Step 4: Connect Computer to Drone Wi-Fi

Not downloaded yet? Download plotter.py — this is the script you run below.

Run plotter.py:

python plotter.py

Step 5: Control Drone Flight

Observe the altitude and attitude curves plotted in real-time on the computer.

Step 6: Challenge

Modify plotter.py to add “altitude anomaly alert”, displaying red warning in terminal when altitude change exceeds 0.5m/s.

Troubleshooting

Cannot connect to Wi-Fi

• Check if password is correct
• Confirm drone is powered on

Data not displaying

• Check if IP address is correct
• Confirm firewall settings

Achievement

Congratulations! You have implemented the drone’s data visualization function, which is an important tool for debugging!

Next Steps

In the next project, you will learn how to achieve simple communication between two drones.