csudtest.c

  // initialize usb
  UsbInitialise();

  while (1) {
      unsigned int kbd_addr;
      unsigned int keys[6];
      unsigned int key;

      if (kbd_addr == 0) {
          // Is there a keyboard ?
          while(KeyboardCount() == 0) {
              UsbCheckForChange();
              delay_ms(100);
          }
          println("Found: keyboard");
          kbd_addr = KeyboardGetAddress(0);
      }

      if (kbd_addr != 0) {
          for(int i = 0; i < 6; i++) {
              // Read and print each keycode of pressed keys
              key = KeyboardGetKeyDown(kbd_addr, i);
              if (key != keys[0] && key != keys[1] && key != keys[2] && \
                  key != keys[3] && key != keys[4] && key != keys[5] && key) {
                  uart_puthex(key);
                  uart_putchar(' ');
              }
              keys[i] = key;
          }

          if (KeyboardPoll(kbd_addr) != 0) {
              kbd_addr = 0;
              println("Lost: keyboard");
          }
      }
  }