DFRobot Fermion: ADKey Board-10 Keys (Breakout) drives DFPlayer pro, DFPlayer mini, and voice recorder module without programming or using various resistors. This board offers 20 delicate button caps with a comfortable hand feel and is easy to be integrated into projects. The ADkey board features a welding pad on both sides that offer a connection to the favorite keys to the board. This board can be used as the ADkey input of the main controller that allows the expansion of 10 keys of the mainboard via only one analog port. The ADkey board operates at the 3.3V to 5V voltage range.