1. Analog output (RP, RN, LP, LN), I2S output (BCK, LRCK, DATA), SPDIF output (DATA)2. Function keys: KEYCOM, PLAY, VOL+, VOL -, PREV, NEXT, high level 3.3V is valid.Key functions are described as follows:PLAY: play/pause (short press); Re pair (long press 2.5S); Clear pairing list (long press 5S)VOL+: volume increase (short press, long press and continuous volume increase)VOL -: Volume decrease (short press, long press, continuous volume decrease)PREV: Previous song (short press)NEXT: Next song (short press)KEYCOM: key common terminalLED lamp: in pairing state, two lamps flash alternately; Pair successfully, single lamp flashesAlways paired when there is no connection, no standbyControl the mute pin MUTE of the external power amplifier (with sound: output high 3.3V)Support decoding format:Single output: support /AAC//APTXLLDual output: support /AAC//APTXLLSingle output with prompt tone, some external DACs do not play prompt tone, but do not affect music playing; Dual output without prompt toneNote:due to different production batches, the appearance printing is different, which does not affect the use.Specification:A:Analog Single OutputColour:As ShownMaterial:PlasticPackage Contents:1 * Audio moduleOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.