Instructions for GYBT321F Bluetooth audio host to transmit and connect TWS headset back connection and active connection

Many Bluetooth headset display rack applications require a Bluetooth transmitter module to send input audio to the Bluetooth headset. Based on the Bluetooth transmission solution GYBT321F, the application of being connected back to TWS headsets or other Bluetooth headsets is added.

Solve the tedious operation of entering pairing mode every time for many Bluetooth headsets or TWS wireless Bluetooth headsets.

Here are a few concepts: [Mobile phone = host] [Bluetooth headset = slave] [GYBT321F Bluetooth audio transmitter = host].

Function Description

Conventional Bluetooth headsets are basically the same. There are two logics for powering on:

Logic 1

1. When booting, it will automatically “reconnect” to the last connected main device. If there is a main device, it will actively initiate “reconnection”. If there is no main device, it will stop there.
2. If you need to enter pairing mode, press and hold a button to enter pairing mode.
3. This way other main devices can search for it.

For example: the entire series of airpods follows this logic, and Bose’s headphones also follow this logic.

Logic 2

1. When the device is turned on, it will automatically “reconnect” to the last connected master device. If there is a master device, it will actively initiate a “reconnection”.
2. If not, wait for about a few seconds and automatically enter pairing mode, no need to press buttons to intervene.
3. This logic is not mainstream and is mainly used in some Bluetooth speaker applications.

For example: small speakers that cost tens of dollars all have this logic, so this brings challenges to our Bluetooth transmission, because the Bluetooth transmitter host actively connects to the slave device when it is powered on, and cannot be connected back, requiring a “slave device” Enter pairing mode to find the slave device = headset

Therefore, it is very painful to face Logic 1 products. You have to press the slave button every time to enter pairing mode. Logic 2 product types are relatively okay. Anyway, waiting for the slave to connect back timeout and automatically enter pairing, and then connect again. That’s it, it’s not troublesome to operate.

The new firmware here is to solve the problem of reconnection. The logic is as follows:

1. When GYBT321F is powered on, it automatically enters the “reconnected” state. If you need to connect to the slave, initiate a search AT command, or press the button 0 ohm to initiate a connection. For details, see the “silk screen PP” button on the test demo board of GYBT321F.
2. After the connection is successful, if the slave device returns to the charging compartment, the GYBT321F will be disconnected. It will also be in the connected state and will not actively initiate the connection. In this case, once the headset is taken out of the compartment, it can be returned to the charging station. Connect to GYBT321F.
3. If GYBT321F is powered on again, it will actively connect to the last connected “slave” device. Note that this is not just connecting the last device, it will not look for a new device again. If it cannot be found, it will also be in a waiting state.

Instructions

Taking the GYBT321F test board as an example, the firmware must be updated to “updata_0157_No active search at boot_Button 0 ohm to start search_Support headphone reconnection 20231228.zip”.

1. The chip adds log printing operation, as shown below. Note that the log output of the chip is the TX of the serial port, using pin 1 of the chip = PC5, and does not support the TF card interface. Adding this log output is to facilitate customers to find problems and facilitate debugging. After all, this is more complicated and there may be various other problems. You need to consult this log to judge the problem. It is just a debugging method and has no other functionality. role.
2. The indicator light pin of the chip is pin 15. It flashes slowly when it is turned on. Press the 0 ohm button of adkey = [silk screen PP button], and the indicator light will flash quickly, which means searching for peripheral devices = random search to connect to whom. That’s who it is and save it.
3. The chip always flashes slowly when it is powered on, waiting for the slave device to connect.
4. When using it, the user can bind it to the TWS headset during the sample stage. In the later stage, there is no need to press the button to search for the device. If an abnormality occurs, the user can press the button and repeat the second step.

Dongguan Geyuan Electronics Co., Ltd. is a high-tech company specializing in the research and development and sales of voice chips. All personnel have profound industry backgrounds. The company is engaged in voice chip research and peripheral circuit development; at the same time, we formulate voice product development plans for customers with special needs, and implement the plans to complete product development, testing, sound processing, and a series of services including product practical application guidance. . The business scope involves automotive electronics (such as reversing radar\anti-theft devices), multimedia (such as advertising machines), home anti-theft (such as voice prompts), toys, electronic products, etc.