In this example we will connect an Android device to an Arduino using class Bluetooth with the HC 05 module. Working with this module is simple. Connect the power and gnd pins and connect the HC05 RX pin to an Arduino TX pin and the HC05 TX pin to an Arduino RX pin. The HC05 RX pin expects 3.3...
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Data freezing after period of time when turned on and off
You should have a look at the messages received at both ends, BT doesn't always send them as a contiguous series, they get broken up and you need to collect them(usually by knowing the number of bytes being sent or having an end character)
Had this issue myself where BT sent one byte and then the rest... I still don't understand this behavior)