Default firmware:

1. Support SBC and AAC decoding, no call function, optional I2S and analog output

2. Key Description:

● SYS_ CTRL: high-level startup, low-level shutdown, startup will automatically enter the pairing mode

● pio2: short press to pause the playback, long press for 3 seconds to enter the pairing, and long press for 5 seconds to clear the pairing record

● pio3: short press the previous song and long press the volume to decrease

● Pio4: press one song for a short time and press the volume for a long time

● pi5: connected, not connected

● pio19: audio output high level, no audio low level

3. Description of indicator light:

● Bluetooth not connected: LED0 LED1 alternate flash

● Bluetooth connected: LED1 is always on

● Bluetooth audio playback: LED1 is always on

Note: the use of USB sound card must be connected to four wires of the module, usbdp, usbdn, vchg and GND