User's Manual

HF-BL100-CU Low Energy Bluetooh（BLE 4.0）Module User Manual
Shanghai High Flying Electronics Technology Co., Ltd www.hi-flying.com - 19
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After receive data from MCU serial, module will judge if it is AT command, if it is, module
will execute the command, if not, module will transmit the data to APP under BLE connection and
notify mode enabled status.
After module receive APP data, output the data to MCU via serial interface.
If module system status changed, module will send status notification character to MCU,
such as disconnect, connect, broadcast.
Bluetooth protocol require that the minimum connect interval is 7.5ms. Default connect
interval is 20ms (comply with IOS regulation), if need to save power and apply low speed
transmit mode, user can adjust connect interval through AT command ( the maximum connect
interval is 2000ms, comply with IOS regulation)
The calculation of transmit speed : the data packet of each connect interval from APP to
module is 1 packet, max 4 packet can be transmit from module to APP in each interval (the
packet qty is related to module CPU capacity) . There is max 20 bytes in each packet, if connect
interval is T (unit :ms), then max transmit speed V (unit is byte/s) is :
Vmodule = 20*4*1000/T (V only related T )
Vapp=20*1000/T (V only related T )
Vapp： if module connect interval is 20ms, then each interval can transmit max 20 bytes, so
theoretically the max speed is 20x50 =1k byte/s. Test shows the transmit from APP to
module is stable and reliable.
Vmodule： if module connect interval is 20ms, then each interval can transmit max 80 bytes,
so theoretically the max speed is 80x 50=4k byte/s. Test shows that if transmit speed under
2kbyte/s, there is few chances of leaking packet. For safety consideration, it is recommended
to do verification and re-transmit at up level whatever it is low speed or high speed application.
In Android application, it is recommended to lower connect interval to increase speed.
Below is the example of 20ms connect interval communication mode, user can self-configure.
The lower the Speed, the lower the packet lost ratio.