The Dutch company DGT manufactures a wide variety of electronic chessboards.
Since v5.7, Chess for Android can connect to a DGT chessboard over bluetooth or USB (including older DGT models that use the RS-232 connector) on devices with Android 6.0 and up. Long press the notation window in Chess for Android to open the extended menu. Then select "Connect to EBoard", pick either the DGT bluetooth or DGT USB, choose an initial orientation (white at bottom when checked) and LED function (enabled when checked, but disabled by default, since most DGT chessboards do not support LEDs), press "OK", and select the right device.
Setting up the start position with white on either the bottom or top of the electronic chessboard will start a new game with Chess for Android using that orientation. Move a piece to make a move, and follow the computer's response shown by the GUI. To capture, remove the opponent's piece from the chessboard. To castle, move the king first two squares to the left or right. To capture en-passant, move your own pawn first before removing the opponent's pawn. To promote, move your own pawn to the last rank, select the promotion piece on Chess for Android, and then replace the pawn with that piece on the electronic chessboard. To set up a position, long press the notation window, pick "Position Setup", after which Chess for Android continuously syncs its internal chessboard with the electronic chessboard. After pressing "OK", the game can proceed from the given position (if valid).
When LEDs are enabled in the dialog and available on the DGT chessboard, such as on the Revelation II, the computer move is indicated with LEDs. Similarly, if an illegal move is made, or the electronic chessboard is somehow out-of-sync with Chess for Android, the LEDs are used to indicate the difference. Correct all differences before proceeding with the game. Likewise, if the game navigation buttons are used to go backward or forward in a game, the LEDs indicate how to resolve differences. Without LEDs, the GUI appears unresponsive when an illegal move is made or the electronic and GUI's chessboards are out-of-sync. In such cases, carefully match the position on the electronic chessboard with the GUI's chessboard before proceeding, or use the position setup to correct the difference (this may break the game flow, however).
Other features, including playing against third party chess engines, are explained in the Chess for Android Manual and the instructional video below.