AC6921A is a stereo 5.0 Bluetooth, which supports multi-function chips such as SD card, U disk, FM, etc.As a single-chip Bluetooth solution, it is widely used in Bluetooth speakers, Bluetooth pair box, dot matrix screen and LED digital tube speakers.

1. Support Bluetooth, USB device, TF card, FM, AUX, call

2. Support 10 AD buttons, support multiple I/O buttons

3. Fewer peripheral components, chip on all sides, is conducive to production

4. Support remote control function

5. Support the display function of dot matrix screen, digital screen, LCD screen

6. Support IIS output

7. Support optical fiber signal input

8. Bluetooth version: compatible with Bluetooth V5.0+BR+EDR+BLE

AC6921A has flexible I/O settings:

33 GPIO pins

All GPIO pins can be individually programmed as input or output

All GPIO pins can be individually selected for internal pull-up/pull-down

External wake-up/interrupt can be performed on all GPIO pins

Support CMOS/TTL level Schmitt trigger input

Design considerations:

1. In the soft switch scheme, the main control VBAT is continuously connected to the battery, and the minimum standby power consumption is about 2uA or less.

2, RTCVDD is the internal RTC module power supply, continuous power in sleep mode, this pin must be connected to 105 capacitors,

3. The PR port is used to wake up IO, both high and low levels can wake up. To wake up the key switch, please use the PR2 port low level to wake up. Because PR2 long press has a reset function (low level reset is effective), it can solve the problem of crashing and not booting under special circumstances.

4. If the solution only needs a soft switch machine and no RTC is required, the 32K crystal oscillator can be saved.

5. The decoupling capacitors of the main power supply must be placed close to the chip, and the loop ground of the decoupling capacitor must be returned to the power supply ground as short as possible.

6. For customers with high FM requirements, please reserve FM amplifier circuit, the sensitivity can be increased by more than 2dBu. The ground spacing of FM signal lines is at least 0.6MM.

7. To ensure the safety and reliability of the product, the battery must use a battery with a protective plate.