I'm buiding a project with the Arduino and Bluetooth HC-05 module that receives the MACs of Bluetooth devices around (does not connect, just inquiry). It works, but I want a better performance in detecting devices, because it doesn't find devices that stay less than 2 seconds in the area. So, I want it to work faster, detecting even if the device stays for 1 second (or maybe less) in the range of the HC-05.

-First, I tried to select the baud-rate (from 9600 to 1382400) of USART, but I tested it, and it did not change anything.

-Then, I tried to config the period and the duration of the inquiry process by "AT+IPSCAN", but, for any value I adjust, also results in anything.

Thought maybe I did not configure parameters, but I tested "AT + IPSCAN?" and "AT + UART?" and the values are those that I set.

This is strange, but I could not find a solution. Does anyone know what it could be?


You can't change how fast Bluetooth devices report their presence.

Bluetooth works the opposite way that you expect. An inquiry doesn't actively request what devices are there. Instead it sits and listens passively for devices to announce that they are there.

If a device enters the target zone and then leaves again before it has broadcast it's "I am here" signal there is nothing you can do.

That is why inquiries take so long. They wait enough time for devices nearby to announce that they are here.

I am not familiar with that specific module, so I don't know if it is always listening in the background and maintaining a list, or just listening during and enquiry, but either way the onus is on the remote device to announce that it is there.

  • The config "AT + IPSCAN", according to the datasheet of HC-05, sets the time and duration that the device do an inquiry (if is listening) or scan (if is sending "I am here"). So, I understood that if I change these parametres, I'm doing exactly what you said thats it's not adjustable. I can maybe be wrong, but it's make sense in my mind and it's consistent with my previous research of this topic. The problem is that, in practice, it doesn'st really change anything, but would not make sense it has this configuration – TuLiO Aug 17 '18 at 16:39

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