Bluetooth audio transmitter module: How to connect Bluetooth headset

How does the Bluetooth headset connection in the Bluetooth transmitter module operate?

Take the GYBT321F module of Geyuan Electronics as an example.

Because Bluetooth audio products are basically divided into three categories:

The first category: Bluetooth headsets, including: tws wireless headsets, such as airpods, headsets such as Bose qc35 series, etc.

The second category: Bluetooth speakers, conventional large speakers above 20W, and small speakers around 5W.

The third category: car Bluetooth, including after-installed Bluetooth modules, original Bluetooth, etc.

These three types of products are different in terms of Bluetooth connection mechanism.

A detailed description

Category 1: Basic operating logic of Bluetooth headsets:

1. When turning on the device, it will automatically “reconnect” to the last connected main device. If there is a main device, it will actively initiate a “reconnect”. If there is no main device, it will stop there. After timeout, it will automatically shut down.
2. If you need to enter pairing mode, long press a button to enter pairing mode, so that the new main device can find it and initiate a connection.

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

Category 2: Basic operating logic of Bluetooth speakers:

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 it will automatically enter pairing mode. No need to press buttons to intervene. Other hosts can search for connections.
3. This logic is not mainstream. It is mainly used in some Bluetooth speaker applications. For example, small speakers that cost dozens of yuan all have this logic.

Category 3: Basic operating logic of in-vehicle Bluetooth

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, it will stop there and will not automatically enter pairing mode.
3. If you click on the display to enter pairing mode, and the host connects at this time, there will be a 6-digit password for interaction and confirmation. This is also a major feature of car Bluetooth. This leads to the fact that many Bluetooth transmitting modules have no way to connect to car Bluetooth.

Introduction to Bluetooth transmitter module

1. Support Bluetooth audio stereo transmitting and receiving, two-in-one. Bluetooth transmitter supports connecting Bluetooth headsets, Bluetooth speakers and other slave devices.
2. Bluetooth reception: supports connection to main devices such as mobile phones, tablets, computers, etc. And some commonly used control functions.
3. Audio sources supported by Bluetooth transmission: AUX input, U disk, TF card, computer PC sound card, SPIFLASH memory.
4. Bluetooth emission sound delay: less than 300ms. Supports serial port AT command control.
5. Rich usage information, refer to PCB, usage video tutorials, mobile phone transparent transmission video tutorials, and serial AT video tutorials.
6. Ultra-low cost, large quantity and good price, super simple peripherals, only 5 capacitors are needed.
7. Bluetooth transmission support: random search after power-on, list search [same effect as mobile phone], specify address or name to connect.
8. We develop the functional firmware ourselves and it is very flexible. Even if there are needs that cannot be met, we can communicate and develop them.
9. Wireless serial port data can be transparently transmitted between master and slave, and the baud rate can be set. It also supports serial port AT command control.

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.