The USB-HID Library is built into Arduino, there is no external installation required. Verify that you have a Metro Express, then copy and paste the code below into the Arduino Editor. Then, compile and upload.
/*
* USB Blog Buddy
* a USB-HID Scroll Wheel for Metro Express
*
* by Brent Rubell for Adafruit Industries. Support Open Source, buy Adafruit!
*/
// include the mouse library
#include <Mouse.h>
// trimpot pin
const int trimPin = A0;
// button pin
const int buttonPin = 2;
// reduces scrolling speed (ms)
const int scrollDelay = 100;
// trimpot value
int trimValue = 0;
// button state
int buttonState = 0;
void setup() {
// start serial monitor at 9600 baud
Serial.begin(9600);
// start the mouse
Mouse.begin();
}
void loop() {
// read the button state
buttonState = digitalRead(buttonPin);
if (buttonState == HIGH) {
// stop the mouse if button not pressed
Mouse.end();
}
else {
// start the mouse (if stopped)
Mouse.begin();
// read the trimpot value
trimValue = analogRead(trimPin);
// map the trimValues to scroll wheel down (-neg values) and up (+pos values)
trimValue = map(trimValue, 0, 1023, -5, 5);
// move the mouse wheel (dont change cursor position)
Mouse.move(0, 0, trimValue);
// reduce the scrolling speed
delay(scrollDelay);
}
}
When you press the push button, the Metro Express will take control of your mouse and start scrolling the mouse wheel.
Scroll Page Up: Move the potentiometer such that the arrow on it faces towards the top of the breadboard
Scroll Page Down: Move the potentiometer such that the arrow on it faces towards the bottom of the breadboard
I don't see anything moving on my screen
Check your wiring, the library for USB interfacing is built into Arduino and should automatically start when you upload this code.
Page last edited January 22, 2025
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