$ vcgencmd get_throttled
throttled=0x50005

 05   00   00   00   05
0101 0000 0000 0000 0101
                       ^	(0x000001)  0: under-voltage
					  ^     (0x000002)  1: arm frequency capped
                     ^      (0x000004)  2: currently throttled
   ^                        (0x010000) 16: under-voltage has occurred
  ^                         (0x020000) 17: arm frequency capped has occurred
 ^                          (0x040000) 18: throttling has occurred