Using Raspberry Pi Pico as an HID to Control Mouse Movements and Keyboard Strokes

The Raspberry Pi Pico, a microcontroller based on the RP2040 chip, can emulate a Human Interface Device (HID) like a keyboard or mouse. This tutorial will guide you through setting up your Raspberry Pi Pico as an HID device to send keyboard strokes and control mouse movements.

Prerequisites

Hardware

Software

Flash MicroPython Firmware with HID Support

By default, the official MicroPython firmware does not include HID functionality. We will use a custom MicroPython firmware that supports HID.

1. Download the MicroPython firmware with HID support from a trusted source (e.g., https://github.com/adafruit/circuitpython).
2. Put the Pico in bootloader mode by holding the BOOTSEL button while plugging it into your computer via USB.
3. Drag and drop the downloaded .uf2 file onto the mounted RPI-RP2 drive.

Once the Pico restarts, it is ready to run MicroPython.

Install Required Libraries

To use the HID functions, you need to install the usb_hid library.

1. Open Thonny IDE.
2. Connect your Pico and open a new script.
3. Import the necessary libraries:

import time
import usb_hid
from adafruit_hid.keyboard import Keyboard
from adafruit_hid.keycode import Keycode
from adafruit_hid.mouse import Mouse

Emulating a Keyboard

The following code sends a “Hello, World!” message when the Pico is connected:

kbd = Keyboard(usb_hid.devices)
time.sleep(1)  # Allow time for HID initialization

kbd.send(Keycode.H, Keycode.E, Keycode.L, Keycode.L, Keycode.O, Keycode.COMMA, Keycode.SPACE,
         Keycode.W, Keycode.O, Keycode.R, Keycode.L, Keycode.D, Keycode.EXCLAMATION)

This script mimics pressing the keys HELLO, WORLD! on a standard keyboard.

Controlling Mouse Movements

To control the mouse, use the Mouse class:

mouse = Mouse(usb_hid.devices)
time.sleep(1)

# Move the mouse to the right
mouse.move(x=50)
time.sleep(1)

# Move the mouse down
mouse.move(y=50)
time.sleep(1)

# Perform a left-click
mouse.click(Mouse.LEFT_BUTTON)

This code moves the mouse cursor and performs a left-click action.

Automating Keyboard and Mouse Actions

You can create automation scripts, such as making the Pico send keystrokes when a button is pressed. Here’s an example:

import machine
button = machine.Pin(2, machine.Pin.IN, machine.Pin.PULL_UP)

while True:
    if not button.value():  # When button is pressed
        kbd.send(Keycode.A)  # Simulate pressing 'A'
        time.sleep(0.5)  # Prevent spamming

Conclusion

With these steps, you can turn your Raspberry Pi Pico into a powerful HID device. You can use it for automation, accessibility solutions, or even creative input devices. Experiment with different key sequences and mouse movements to build your custom HID solutions!