KEYBOARD.ino

#include <M5Stack.h>

#define KEYBOARD_I2C_ADDR 0X08
#define KEYBOARD_INT      5

void setup() {
    M5.begin();
    M5.Power.begin();
    Wire.begin();
    M5.Lcd.setTextFont(2);
    M5.Lcd.println("FACES Keyboard I2C Read Example");
    pinMode(KEYBOARD_INT, INPUT_PULLUP);
}

void loop() {
    if (digitalRead(KEYBOARD_INT) == LOW) {
        Wire.requestFrom(KEYBOARD_I2C_ADDR, 1);  // request 1 byte from keyboard
        while (Wire.available()) {
            uint8_t key_val = Wire.read();  // receive a byte as character
            if (key_val != 0) {
                if (key_val >= 0x20 && key_val < 0x7F) {  // ASCII String
                    Serial.print((char)key_val);
                    M5.Lcd.print((char)key_val);
                } else {
                    Serial.printf("0x%02X ", key_val);
                    M5.Lcd.printf("0x%02X ", key_val);
                }
            }
        }
    }
}