HC-05 troubleshooting
Some HC-05 modules are more equal than others I've been playing with some cheap HC-05 bluetooth modules I picked up off Amazon. They are a very convenient and easy way to add remote control to a project, using two wire UART (RX/TX) in the usual way, so can replace an existing serial connection to a PC for example. They work pretty much out the box and there are loads of guides to using them. I thought I would share a few thoughts on using these modules though as I've come to realise that all HC-05s are not created equal... There are some visual clues. On the back of my modules I have an "EN" pin whereas some other HC-05 modules have a "KEY" pin. The KEY pin is used to place the module into "AT command mode", by putting it high (3.3V) before powering up the module. I initially thought that the EN pin was analogous to the KEY pin (a different name perhaps), but the EN pin can be used to disable the bluetooth module , which I guess is