Week 2 - Bluetooth Connection, HID Control & Motor Optimization & 3D Printed Housing

Week 2 - Bluetooth Connection, HID Control & Motor Optimization & 3D Printed Housing

šŸ“… Date: 2025-02-09 – 2025-02-15
šŸ·️ Tags: Year 2 Project, ESP32-S3, Smart Knob, HID, Bluetooth, FOC

šŸŽÆ This Week's Goals

  1. Implement Bluetooth HID communication so that the ESP32-S3 can act as a wireless input device.
  2. Integrate motor control with force feedback to improve user interaction.
  3. Test and refine the Bluetooth HID response time and stability.
  4. Design a suitable 3D knob housing

šŸ”¹ 1️⃣ Bluetooth HID Integration

To enable wireless control, we implemented Bluetooth HID (Human Interface Device) on the ESP32-S3, allowing the knob to function as a mouse, keyboard, and Surface Dial alternative.

šŸ“Œ Key Features Implemented

✅ Rotational input for scrolling (mapped to arrow keys or volume control).
✅ Short press for click-like actions (e.g., Enter, Ctrl + Z).
✅ Long press and hold for function switching (e.g., toggle between scrolling & zooming).
✅ Bluetooth auto-reconnect support for seamless operation.

šŸ“Œ Code Implementation - BLE HID Setup

The following code initializes ESP32-S3 as a Bluetooth HID keyboard and sends keypress events based on knob rotation.

šŸ“Œ How This Works

  1. ESP32-S3 registers as a Bluetooth keyboard.
  2. Knob rotation is mapped to arrow keys (for scrolling).
  3. Knob press sends a key command (e.g., Ctrl, Enter).

✅ This allows the knob to function as a wireless input device for various applications.


šŸ”¹ 2️⃣ Motor Control Optimization

To provide force feedback and improve rotation feel, we integrated Field-Oriented Control (FOC) for smoother motor control.

šŸ“Œ Challenges Faced

❌ Initial motor response was inconsistent, leading to jitter.
❌ Resistance wasn't dynamically adjusted based on rotation speed.
❌ Torque control needed real-time feedback adjustments.

šŸ“Œ Code Implementation - FOC Motor Control

We used the SimpleFOC library to control the motor’s torque and improve force feedback.


šŸ“Œ How This Works
  1. Uses FOC (Field-Oriented Control) for smooth motor feedback.
  2. Adjusts torque dynamically to provide different levels of resistance.
  3. Prevents unnecessary jitter and sudden torque changes.
✅ This ensures a more natural rotational feel for the knob.

šŸ”¹ 3️⃣ Designing a 3D-Printed Housing

šŸ“Œ Issues with the Initial Design

We identified several problems with our initial 3D-printed design:

  • Insufficient support structure, leading to flexing under pressure.
  • Motor misalignment, causing uneven rotation.
  • Loose fit between components, leading to vibrations.

šŸ“Œ Improvements & New Design Features

✅ Reinforced internal structure to prevent bending.
✅ Added motor mounting points for better alignment.
✅ Redesigned PCB mounting slots for secure connections.
✅ Integrated cable management system to reduce wire clutter.

šŸ“Œ 3D Printing & Testing

  • Printed the new housing using PLA material for initial testing.
  • Checked component alignment and made small adjustments.
  • Tested real-world usability and ergonomics.


First version of 3D printing kit


Several test 3D printed bases (the bottom one worked best)

šŸ”„ Challenges & Team Collaboration

IssueSolution
Bluetooth connection dropped frequentlyAdjusted BLE power settings & optimized pairing process
HID input lagTweaked BLE polling rate and input event timing
Motor response was inconsistentTested FOC implementation
Housing was unstableAdded reinforcements & improved design fit

Through effective teamwork, we quickly resolved issues, improved design efficiency, and optimized motor control.

šŸ“Œ Next Week's Plan

  • Enhance HID control: Add gesture-based inputs & configurable modes.
  • Improve FOC performance: Further optimize motor torque & speed control.

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