Merge pull request #73 from henrygab/patch-1

Use only unsigned value for array access

Author: hathach

src/Adafruit_USBD_HID.cpp

@@ -177,10 +177,11 @@ bool Adafruit_USBD_HID::keyboardReport(uint8_t report_id, uint8_t modifier,
 bool Adafruit_USBD_HID::keyboardPress(uint8_t report_id, char ch) {
   uint8_t keycode[6] = {0};
   uint8_t modifier = 0;
+  uint8_t uch = (uint8_t)ch;
 
-  if (_ascii2keycode[ch][0])
+  if (_ascii2keycode[uch][0])
     modifier = KEYBOARD_MODIFIER_LEFTSHIFT;
-  keycode[0] = _ascii2keycode[ch][1];
+  keycode[0] = _ascii2keycode[uch][1];
 
   return tud_hid_keyboard_report(report_id, modifier, keycode);
 }