こんなんでどうでしょう？

[kbtest.ino]

#include <TFT_eSPI.h>
#include <SPI.h>
#include <KeyboardController.h>

// TFT 制御用
TFT_eSPI tft;

// USB 制御用
USBHost usb;

// キーボード制御用
KeyboardController keyboard(usb);

uint32_t lastUSBstate = 0;

void setup() {
  // TFT の初期化
  tft.init();
  tft.begin();
  tft.setRotation(3);

  // キーボードの初期化
  if (usb.Init())
    tft.println(F("USB host did not start."));
  delay( 20 );
  digitalWrite(PIN_USB_HOST_ENABLE, LOW);
  digitalWrite(OUTPUT_CTR_5V, HIGH);
}

void keyReleased() {
  char c = keyboard.getKey();
  tft.println(c);
}

void loop() {
  usb.Task();
  uint32_t currentUSBstate = usb.getUsbTaskState();
  if (lastUSBstate != currentUSBstate) {
    tft.print("USB state changed: 0x"); 
    tft.print(lastUSBstate, HEX); 
    tft.print(" -> 0x"); 
    tft.println(currentUSBstate, HEX);
    switch (currentUSBstate) {
      case USB_ATTACHED_SUBSTATE_SETTLE: tft.println("Device Attached"); break;
      case USB_DETACHED_SUBSTATE_WAIT_FOR_DEVICE: tft.println("Detached, waiting for Device"); break;
      case USB_ATTACHED_SUBSTATE_RESET_DEVICE: tft.println("Resetting Device"); break;
      case USB_ATTACHED_SUBSTATE_WAIT_RESET_COMPLETE: tft.println("Reset complete"); break;
      case USB_STATE_CONFIGURING: tft.println("USB Configuring"); break;
      case USB_STATE_RUNNING: tft.println("USB Running"); break;
    }
    lastUSBstate = currentUSBstate;
  }
}