In this example, you'll upload the sketch to turn your QT Py into a simple four key keyboard.
- Button 1 input to board A0 (blue wire)
- Button 1 ground to board GND (black wire)
- Button 2 input to board A1 (green wire)
- Button 2 ground to board GND (black wire)
- Button 3 input to board A2 (yellow wire)
- Button 3 ground to board GND (black wire)
- Button 4 input to board A3 (orange wire)
- Button 4 ground to board GND (black wire)
Library Installation
You can install the Adafruit_NeoPixel library for Arduino using the Library Manager in the Arduino IDE.
Click the Manage Libraries ... menu item, search for Adafruit_NeoPixel, and select the Adafruit NeoPixel library:
There are no additional dependencies for this library.
This example also requires the Adafruit TinyUSB library. You should already have this library installed after following the steps on the Arduino IDE setup page.
// SPDX-FileCopyrightText: 2024 Ha Thach for Adafruit Industries
//
// SPDX-License-Identifier: MIT
/*********************************************************************
Adafruit invests time and resources providing this open source code,
please support Adafruit and open-source hardware by purchasing
products from Adafruit!
MIT license, check LICENSE for more information
Copyright (c) 2019 Ha Thach for Adafruit Industries
All text above, and the splash screen below must be included in
any redistribution
*********************************************************************/
#include <Arduino.h>
#include "Adafruit_TinyUSB.h"
#include <Adafruit_NeoPixel.h>
const int neopixel_pin = PA4;
#define LED_COUNT 1
Adafruit_NeoPixel pixels(LED_COUNT, neopixel_pin, NEO_GRB + NEO_KHZ800);
//------------- Input Pins -------------//
// Array of pins and its keycode.
// Notes: these pins can be replaced by PIN_BUTTONn if defined in setup()
uint8_t pins[] = {PB1, PB0, PA1, PA0}; //A0, A1, A2, A3
// HID report descriptor using TinyUSB's template
// Single Report (no ID) descriptor
uint8_t const desc_hid_report[] = {
TUD_HID_REPORT_DESC_KEYBOARD()
};
// USB HID object. For ESP32 these values cannot be changed after this declaration
// desc report, desc len, protocol, interval, use out endpoint
Adafruit_USBD_HID usb_hid;
// number of pins
uint8_t pincount = sizeof(pins) / sizeof(pins[0]);
// For keycode definition check out https://github.com/hathach/tinyusb/blob/master/src/class/hid/hid.h
uint8_t hidcode[] = {HID_KEY_0, HID_KEY_1, HID_KEY_2, HID_KEY_3};
bool activeState = false;
// the setup function runs once when you press reset or power the board
void setup() {
pixels.begin();
// Manual begin() is required on core without built-in support e.g. mbed rp2040
if (!TinyUSBDevice.isInitialized()) {
TinyUSBDevice.begin(0);
}
// Setup HID
usb_hid.setBootProtocol(HID_ITF_PROTOCOL_KEYBOARD);
usb_hid.setPollInterval(2);
usb_hid.setReportDescriptor(desc_hid_report, sizeof(desc_hid_report));
usb_hid.setStringDescriptor("TinyUSB Keyboard");
// Set up output report (on control endpoint) for Capslock indicator
usb_hid.setReportCallback(NULL, hid_report_callback);
usb_hid.begin();
// overwrite input pin with PIN_BUTTONx
#ifdef PIN_BUTTON1
pins[0] = PIN_BUTTON1;
#endif
#ifdef PIN_BUTTON2
pins[1] = PIN_BUTTON2;
#endif
#ifdef PIN_BUTTON3
pins[2] = PIN_BUTTON3;
#endif
#ifdef PIN_BUTTON4
pins[3] = PIN_BUTTON4;
#endif
// Set up pin as input
for (uint8_t i = 0; i < pincount; i++) {
pinMode(pins[i], activeState ? INPUT_PULLDOWN : INPUT_PULLUP);
}
}
void process_hid() {
// used to avoid send multiple consecutive zero report for keyboard
static bool keyPressedPreviously = false;
uint8_t count = 0;
uint8_t keycode[6] = {0};
// scan normal key and send report
for (uint8_t i = 0; i < pincount; i++) {
if (activeState == digitalRead(pins[i])) {
// if pin is active (low), add its hid code to key report
keycode[count++] = hidcode[i];
// 6 is max keycode per report
if (count == 6) break;
}
}
if (TinyUSBDevice.suspended() && count) {
// Wake up host if we are in suspend mode
// and REMOTE_WAKEUP feature is enabled by host
TinyUSBDevice.remoteWakeup();
}
// skip if hid is not ready e.g still transferring previous report
if (!usb_hid.ready()) return;
if (count) {
// Send report if there is key pressed
uint8_t const report_id = 0;
uint8_t const modifier = 0;
keyPressedPreviously = true;
usb_hid.keyboardReport(report_id, modifier, keycode);
} else {
// Send All-zero report to indicate there is no keys pressed
// Most of the time, it is, though we don't need to send zero report
// every loop(), only a key is pressed in previous loop()
if (keyPressedPreviously) {
keyPressedPreviously = false;
usb_hid.keyboardRelease(0);
}
}
}
void loop() {
#ifdef TINYUSB_NEED_POLLING_TASK
// Manual call tud_task since it isn't called by Core's background
TinyUSBDevice.task();
#endif
// not enumerated()/mounted() yet: nothing to do
if (!TinyUSBDevice.mounted()) {
return;
}
// poll gpio once each 2 ms
static uint32_t ms = 0;
if (millis() - ms > 2) {
ms = millis();
process_hid();
}
}
void setLED(bool state) {
pixels.setPixelColor(0, pixels.Color(0, state ? 150 : 0, 0));
pixels.show();
}
// Output report callback for LED indicator such as Caplocks
void hid_report_callback(uint8_t report_id, hid_report_type_t report_type, uint8_t const* buffer, uint16_t bufsize) {
(void) report_id;
(void) bufsize;
// LED indicator is output report with only 1 byte length
if (report_type != HID_REPORT_TYPE_OUTPUT) return;
// The LED bit map is as follows: (also defined by KEYBOARD_LED_* )
// Kana (4) | Compose (3) | ScrollLock (2) | CapsLock (1) | Numlock (0)
uint8_t ledIndicator = buffer[0];
// turn on LED if capslock is set
setLED(ledIndicator & KEYBOARD_LED_CAPSLOCK);
}
Confirm that your upload settings match the settings listed here under Tools:
- Board: CH32V20x
- Board Select: Adafruit QTPy CH32V203G6
- USB support: Adafruit TinyUSB with USBD
For the port, select the COM port that matches your QT Py. It will not be labeled like you may be used to with other boards in the Arduino IDE.
Upload the sketch to your board. When you press the buttons connected to pins A0-A3, you'll type 0, 1, 2 or 3.
You can customize the code to send different keycodes. Edit the hidcode[] with the keycodes of your choice.
// For keycode definition check out https://github.com/hathach/tinyusb/blob/master/src/class/hid/hid.h
uint8_t hidcode[] = {HID_KEY_0, HID_KEY_1, HID_KEY_2, HID_KEY_3};
Page last edited January 22, 2025
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