Hardware Components

Overview of the Data Walker hardware components and their specifications.

Core Components

ESP32 Development Board

The brain of the Data Walker. We use the ESP32-2432S028R development board with integrated touchscreen:

• Dual-core 240 MHz processor
• 4MB Flash memory
• 2.8" resistive touchscreen display
• TF (microSD) card slot for data logging
• Micro USB for programming and power
• 1.25mm JST connectors for power, speaker, and extended IO
• Built-in WiFi and Bluetooth (future features)

Hall Effect Sensor

A digital Hall effect sensor detects magnets as the wheel rotates:

• Model: A3144E/A3144
• Type: Digital output
• GPIO: Pin 35
• Trigger: RISING edge
• Debounce: 50ms
• Operating voltage: 3.3V

Wheel Configuration

The wheel and magnet configuration determines measurement resolution:

• Wheel diameter: 125.6mm (4.94")
• Wheel circumference: 394.5mm (15.53")
• Magnets: 3 neodymium (6mm × 3mm disc)
• Magnet spacing: 120° apart
• Distance per rotation: 1.30 feet (394.5mm)
• Resolution per pulse: 131.5mm (5.18")

Display

The integrated 2.8" TFT touchscreen provides the user interface:

• Resolution: 320×240 pixels
• Type: XPT2046 resistive touchscreen
• Interface: SPI with ILI9341 driver
• Update rate: 10 Hz display, 1 Hz speed calculation
• High contrast for clinical visibility
• Touch-based menu navigation

Power

External USB-C power bank provides extended runtime:

• Input: 5V USB-C
• Operating current: 150-200mA typical
• Battery: 5000mAh external power bank
• Runtime: 8-10 hours continuous use

Enclosure

The 3D-printed enclosure protects components and mounts to the walker:

• Material: PETG or ABS for durability
• Mounting: Clip-on design for standard walker frames
• Access: USB port accessible for charging/programming

Connections

The Hall sensor connects to the main unit via an RJ22 (4P4C) cable:

• Pin 1: VCC (3.3V)
• Pin 2: Signal
• Pin 3: Not connected
• Pin 4: GND

Related Pages

• Assembly Instructions
• Wiring Diagram