● Module model: SJR-BTM331

● Bluetooth chip: QCC3031, the module built-in 32M SPI FLASH

● Bluetooth version: 5.1

● Module size: 13mm x 18mm x 2.5mm

● Power supply voltage: 3.0-4.3v

Default firmware:

1. Support sbc, aac, aptx, aptx-HD decoding, no call function, optional I2S, analog output

2. Button description:

● SYS_CTRL: power on at high level, power off at low level, and automatically enter pairing mode after power on

● PIO2: Short press to play and pause, long press for 3 seconds to enter pairing, long press for 5 seconds to clear the pairing record

● PIO3: Short press the previous song, long press the volume to decrease

● PIO4: Short press a song, long press the volume to increase

● PIO5: connected to high level, not connected to low level

● PIO19: There is audio output high level, no audio low level

● PIO20: SPDIF output port

3. Indicator light description:

● Bluetooth is not connected: LED0 and LED1 flash alternately

● Bluetooth is connected: LED1 is always on

● Bluetooth audio playback: LED1 is always on