Popularization of Bluetooth knowledge    earbuds with active noise cancellation

It is necessary to familiarize yourself with several common nouns.
BLE (Bluetooth Low Energy), a subset of the Bluetooth 40 standard, Bluetooth 40 is divided into two parts, one is the high-speed part that is compatible with traditional Bluetooth, and the other is the BLE here, the two major features of BLE: low power consumption, rate is low. So you don't plan to use BLE for audio transmission or file transmission. At present, the maximum transmission rate of BLE can only reach 4~5K bytes/second. www.bjbjaudio.com

The BLE protocol stack, BLE in Bluetooth 40, is just a protocol specification, and the BLE protocol stack is the code implementation of the protocol. The Bluetooth organization SIG is only responsible for formulating the protocol, and how the protocol is implemented needs to be completed by each chip company. It can be understood in this way that the BLE protocol stack is the source code or library pre-compiled by the chip company. www.bjbjaudio.com

CC2540/CC2541, the BLE chip of Texas Instruments Semiconductor Corporation (TI), the BLE protocol stack implemented by TI is also the code implementation of the ble protocol. These BLE codes are running on the CC2540/CC2541 chip. Simply speaking, CC254x is a A 51 single-chip microcomputer with bluetooth function, other microcontrollers have resources. For example, timer, UART, SPI, ADC, GPIO, USB (proprietary to CC2540), 12C (proprietary to CC2541), etc. CC254x also has it, and the BLE protocol stack is also some complicated c language source code (in fact, most of the It is a lib library, and the core source code is not allowed to be disclosed for policy reasons). There is another question, how do we developers develop? www.bjbjaudio.com

The BLE protocol stack implements complex underlying communication, and what data the upper layer wants to send is our developer's business. What we need to do is to modify a lot of code given by others according to a certain format, and then To achieve the functions we want, whether to actively send data to the mobile phone, or receive data from the mobile phone, etc., are all things that our developers need to learn and do. Final question: How to get started? www.bjbjaudio.com 

The ble protocol stack of the IAR for 8051 development environment T is based on the IAR compilation software, and can only use AR. People who learn MCU seem to have more affection for keil, don't worry, the development software is similar, his biggest role is to compile, download, Debugging, as long as these steps are familiar.
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Meet our BLE (CC254x) development devices
Consider a question: why are there so many devices?
Our explanation: The application of CC254x is very wide, and there are three golden applications: 1 serial port transparent transmission, 2 wearable devices, 3 BLE adapter on PC, which corresponds to three devices, with a SmartRF development board with serial port (for Development of most applications), Keyfob anti-lost device development board with three-axis accelerometer (used to develop wearable devices), and finally CC2540USBdongle, which can be directly plugged into the USB port (development of BLE adapter or virtual serial port and other applications). And TI's BLE protocol stack routines are also built on these three devices. The application field is clear. Finally, when everyone is doing product design, the development board circuit is more reference. www.bjbjaudio.com