ESP32-S3 USB to BLE Keyboard Bridge

Transform any USB keyboard into a Bluetooth wireless keyboard using ESP32-S3's native USB-OTG hardware.

What This Does

┌─────────────┐     USB-C OTG     ┌────────────┐     Bluetooth     ┌──────────────┐
│ USB Keyboard│ ◄──────────────►  │ ESP32-S3   │ ◄───────────────► │ PC / Phone   │
└─────────────┘                   └────────────┘                   └──────────────┘

Plug a USB keyboard into ESP32-S3's USB-C port and it becomes a Bluetooth keyboard that can connect to any BLE-compatible device (Windows, macOS, Linux, iOS, Android).

Features

• Native USB Host - Uses ESP32-S3's hardware USB-OTG (no software emulation)
• Multi-Device Support - Switch between 3 paired devices with a key combo
• Low Latency - Direct HID report forwarding
• Universal Compatibility - Works with Windows, macOS, Linux, iOS, Android, Smart TVs

Multi-Device Switching

You can pair with up to 3 different devices (e.g., PC, Laptop, Tablet) and switch between them using your keyboard.

Key Combo	Action	Device Name
Scroll Lock + 1	Switch to Device 1	USB-BLE Dev 1
Scroll Lock + 2	Switch to Device 2	USB-BLE Dev 2
Scroll Lock + 3	Switch to Device 3	USB-BLE Dev 3

How it works:

1. Press Scroll Lock + 1. Pair "USB-BLE Dev 1" with your first computer.
2. Press Scroll Lock + 2. The connection drops. Pair "USB-BLE Dev 2" with your second device.
3. Switch back and forth instantly using the key combos!
4. The active slot is saved and restored on reboot.
5. The LED on GPIO 2 blinks to indicate the current slot (1, 2, or 3 blinks).

USB Keyboard Power

The USB-C port on most ESP32-S3 boards does NOT output 5V!

Even if you power the ESP32-S3 from the 5V pin, that power is NOT routed to the USB-C VBUS line.

Solutions

Option 1: Powered USB Hub (Recommended)

Use a powered USB hub between ESP32-S3 and keyboard:

ESP32-S3 USB-C ──► [Powered USB Hub] ──► USB Keyboard
                         ▲
                    External 5V

Option 2: External Power to Keyboard (untested)

Power the keyboard directly, use USB-C only for data:

                      ┌──────────────┐
    5V Power ─────────┤ USB Breakout ├──── USB Keyboard
    Supply    GND ────┤    Board     │
                      └──────┬───────┘
                             │ D+/D- only (data)
                      ┌──────┴───────┐
                      │   ESP32-S3   │
                      │   USB-C port │
                      └──────────────┘

Steps:

1. Cut a USB cable or get a USB breakout board
2. Connect 5V and GND from your power supply directly to keyboard's USB power
3. Connect only D+ and D- (data lines) through the ESP32-S3 USB-C port

Option 3: ESP32-S3-USB-OTG Board

The ESP32-S3-USB-OTG development board has a dedicated USB-A host port with proper 5V output - no modifications needed.

Option 4: Modify DevKit (Advanced)

Some boards have solder pads to enable 5V on USB-C. Check your board's schematic for pads labeled "USB_OTG" or similar.

Quick Start

1. Clone and Build

git clone https://github.com/KoStard/ESP32S3-USB-Keyboard-To-BLE
cd ESP32S3-USB-Keyboard-To-BLE

# Build with PlatformIO
pio run

# Upload to ESP32-S3
pio run -t upload

Configuration

Device Name

Edit src/Config.h:

#define DEVICE_NAME_1 "USB-BLE Dev 1"
#define DEVICE_MANUFACTURER "Custom"

Board Selection

The project is configured for esp32-s3-devkitc-1. For other boards, edit platformio.ini:

board = esp32-s3-devkitc-1  ; Change to your board

Your board needs to have USB-OTG.

Hardware Limitations and Known Issues

USB Host Channel Limits

The ESP32-S3 has a hardware limitation on the number of USB Host channels (pipes).

Consequence: If you connect a complex hub with multiple devices (e.g., a "Gaming" keyboard that shows up as 3-4 different HID interfaces + a mouse + a hub), you may run out of hardware channels.

• Symptoms: You will see No more HCD channels available in the Serial logs, and some devices or interfaces will fail to initialize.
• Recommendation: Use a simple USB hub and avoid devices that present too many virtual interfaces if you plan to use them simultaneously.