Introduction

HLK-B20 is an new low-consumption Bluetooth BLE 4.2 control module made by Hi-Link. This product is a Bluetooth-compliant module based on universal serial interface. It has built-in BLE 4.2 protocol stack, which can realize data conversion between user serial port and Bluetooth interface. 

Product features

High-speed ARM9E core MCU 

2.4G/1T1R, BLE 4.2 

160k programming space, 20KB RAM 

Power supply voltage 0.9-3.6v 

Ultra low supply voltage, low power consumption 

Built-in crystal, high stability 

Small chip package 4x4 

Rich peripheral interface, SPI, I2C, ADC, UART, PWM, GPIO 

Widely used in the Internet of Things 

High-speed 10-bit multi-channel ADC with internal filtering 

Easy to connect, fast speed

Function description

The module function is mainly to realize the mutual conversion of Bluetooth data and serial data.

                                                           Figure: Serial to BLE mode

In this mode, the BLE Bluetooth device transmits the data to the HLK-B20 module via Bluetooth, and the HLK-B20 module sends the received data from the serial port. When the serial port gets data, the HLK- B20 sends the serial port data from the Bluetooth terminal to realize the conversion of serial data and Bluetooth data. When the HLK-B20 has a Bluetooth device connected, the HLK-B20 will turn off the broadcast of the Bluetooth name, and other Bluetooth devices will no longer be able to connect to the HLK- B20.

Serial port working state conversion

                    Figure: Serial port working state transition

The module defines the working state of the serial port as two modes: transparent transmission mode and AT command mode.

After normal power-on, the module directly enters the transparent mode. If Bluetooth is not connected, the data will not be sent out from Bluetooth. If Bluetooth is connected, the data will be sent out from Bluetooth. In any state, keeping the ES0 pin low for longer than Tes and less than Trst will immediately enter the AT command mode