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Shenzhen Hi-Link Electronic Co., Ltd.
Manual
HLK-B20
4. Function description
The module function is mainly to realize the mutual conversion of Bluetooth data and serial data.
HLK-B20
SERIAL
BLE
COM1
MCU
Bluetooth
device
Figure 4 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.
5. Serial port working state conversion
The module defines the working state of the serial port as two modes: transparent transmission mode
and AT command mode.
Power on
Yes
No
Normal configur.?
Transparent
mode
1.
ES0(PIN5) pin
AT
command
mode
1.at+reconn=0
Figure 5 . Serial port working state transition
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.
