Analog differential output (RP, RN, LP, LN). 3034 supports , AAC, , APTXHD. When is used with a box: the highest protocol is . Clear pairing information: the highest protocol is APTXHD (default for 3034). Supports serial port AT commands, 115200, N, 8, 1, supports Android APP to modify Bluetooth name (supports any language), pairing password, custom EQ, switch prompt tone, with call (select in category) Function keys: KCOM, PLAY, VOL+, VOL-, P/V-, +, MODE, high level 3V3 is effective. Control external amplifier mute foot MUTE (with sound: output high 3V3, no sound: output 0V), Bluetooth connection status output foot BT_HL (Bluetooth connected: output high 3V3, Bluetooth disconnected: output 0V) Button Description: "VOL+": short to increase volume, long to increase volume; "VOL-": short to decrease volume, long to decrease volume; "+": short to play next song, long to increase volume; "P/V-": short to play previous song, long to decrease volume; "PLAY": short to play/pause/answer/hang up, long to reject Special Function Description: "PLAY": long for 3 seconds and release to force pairing mode, long for 6 seconds and release to clear pairing list; "PLAY" + "VOL+": long for 1 second at the same time to enter host mode and search ; "PLAY" + "VOL-": and hold for 1 second to enter slave mode and is searched; "VOL+" + "VOL-": and hold for 1 second to disconnect ; "+" + "P/V-": and hold for 6 seconds and release at the same time to clear pairing information and pairing password, and reset MODE/ key: Bluetooth is not connected to the mobile phone: Short , host mode search (with prompt sound); Double click, slave mode is searched (with prompt sound); and hold for 6 secon and release, clear pairing information, clear pairing password, and reset (with prompt sound). After Bluetooth is connected to the mobile phone: Short : play pause; Double click: next song; and hold for 3 seconds and release, disconnect