Drawing Turtlebot

 *** I tried it on my floor, with a pen that washes away with water – works great! :-) 

Part 1: Hardware Setup

Required Components:

- 2 × 28BYJ-48 Stepper Motors (each controlled via a ULN2003 driver)

- 1 × Hobby Servo

- 1 × ESP32-C3 Mini (with development board)

- 1 × O-Ring (~60 mm) – improves wheel traction

- 6 × M3 screws with nuts

- Jumper wires (female-female)

- Small amount of superglue (for mounting standoffs)

- Power supply (e.g., USB power bank)

- USB cable (for programming the ESP32)

Power Connections:

- 5V: Connect the 5V output from the ESP32 dev board to the VCC pin on both ULN2003 driver boards

- Connect the servo’s red (power) wire to 5V.

- GND: Connect the ESP32 GND to both ULN2003 driver boards and the servo’s black (ground) wire.

*** Note: All grounds must be connected (common ground).

Assembly:

- Mount the motors and their drivers on the left and right side.

- Mount the servo in its holder.

- Attach the ESP32-C3 Mini to its mounting bracket.

Wiring Diagram:

Left Wheel Motor → ULN2003 → ESP32-C3 GPIO:

IN1 → GPIO 1

IN2 → GPIO 2

IN3 → GPIO 3

IN4 → GPIO 4

Right Wheel Motor → ULN2003 → ESP32-C3 GPIO:

IN1 → GPIO 8

IN2 → GPIO 7

IN3 → GPIO 6

IN4 → GPIO 5

Servo:

Signal (yellow/orange) → GPIO 10

Power (red) → 5V

Ground (black) → GND

*** Always check polarity ***


 

Part 2: Flashing the Firmware

To flash the firmware.bin file to your ESP32-C3 Mini:

1. Download the flashing tool and compile it using the latest Arduino IDE.

2. Download the firmware.bin file from: 

[https://github.com/mikaelmoran/TurtlebotEsp32/](https://github.com/mikaelmoran/TurtlebotEsp32/)

3. After flashing the flasher tool, connect to the WiFi:

SSID: ESP32-C3-TURTLE-AP-FLASHER

Password: 12345678

4. Open a browser and go to: [http://192.168.4.2](http://192.168.4.2)

- Upload the firmware.bin file

- The device will reboot with the Turtle firmware.

Part 3: Calibration via Web Interface

After flashing the firmware, calibration is required for accurate movement.

1. Connect to the robot’s WiFi (e.g., TurtleRobot-AP).

2. Open a browser and go to: [http://turtlebot.local](http://turtlebot.local) or use the IP shown in the serial monitor.

3. Two calibration steps are needed:

a) Distance Calibration:

- Click "Drive (200 mm) forward"

- Measure how far it actually moved

- Enter the actual distance and click "Save Distance Calibration"

- Repeat until it matches

b) Rotation Calibration:

- Click "Run Rotation Test (360°)"

- Measure the actual angle rotated

- Enter the value and click "Save Rotation Calibration"

- Repeat until accurate

Proper calibration ensures the robot can reproduce drawings correctly.

If you like it, feel free to support me with a coffee :-) 
 

buymeacoffee.com/mikaelmoran