1. Use KTC2700H Bluetooth module (BES2700H Bluetooth chip). 2. The pinholes are standard 2.54MM spacing, which is convenient for welding and debugging! 3. The board has integrated LEDO and LED1 indicators! 4. Integrated MFB power-on delay circuit, can be used after power on! 5. VDD supply voltage is 3.3V-5V, the voltage cannot exceed 6V! 6. When SPDIF is output, DATA is SPDIF OUT output pin! 7. Board size: 24 x 36.5MM Button: PI00: short press to pause, long press for 3 seconds to enter pairing, Long press for 5 seconds to clear pairing record [PLAY] PIO1: short press to reduce volume [VOL-] PIO2: short press to increase volume [VOL+] PI03: short press to play the previous song [PREV] PI04: short press to play the next song [INEXT] PI05: Bluetooth connection high level (output high level 3.3V) Bluetooth name: KTC2700H 1. Power-on method: power on Power on automatically enters back connection, and automatically enters pairing mode if back connection fails 2. Button PI00: short press to pause, long press for 3 seconds to pair, long press for 5 seconds to clear pairing record Pin definition: 1: DATA: IIS data output 2: BCK: IIS serial clock 3: LRCILK: IIS clock 4: VDD-IN: Power input 5V 5: GND: Power ground 6: SPK-R+: Differential analog signal output 7: SPKR-: Differential analog signal output 8: SPK-L+: Differential analog signal output 9: SPK-L-: Differential analog signal output 10: SPK-EN: Amplifier enable, pull high when there is audio 11: NEXT: Next song button 12: PREV: Previous song button 13: VOL+: Volume plus button 14: VOL-: Volume plus button 15: PLAY: Play/pause button 16: 33-0UT: 3.3V output, used for button common pin 17: LED1: Blue light 18: LEDO: Red light Color: Black Material: PCB Package Contents: 1 * Audio Module Only 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 +/-