开云体育

OK, this is the problem with Chinese cloned parts, anything popular is going to get ripped off, cloned till it's no longer recognizable, and sold for one cent less than the other guys, which is going to drive a race to the bottom (of quality, documentation, repeatability, everything else). Welcome to the world of $10 parts. Not being snarky, but if you want to pay $50 for a BlueTooth interface, it'll come with support, documentation, etc. [I don't want to pay $50 either, and I'm comfortable with the 'self-support' options, which include community support forums like this one.]

As a zeroth step, please tell us exactly which device you have, where you bought it, and when. These things change all the time, but at least we'll have a starting point for helping you. There are dozens of HC05 devices just on Amazon, some of which have buttons and some of which don't. Saying "This one, the one I'm holding in my hand" is less useful to us than a URL.

First, take a step back and take one piece at a time.

You have a nanoVNA, which works. Put it aside for now, that's not your problem.

Power up the BT module and see what it does. While the difference between 1Hz and 2Hz might be difficult to distinguish, try counting off seconds (traditionally "one one thousand, two one thousand, three one thousand") and see how many flashes you get in one second. It'll be close to one or close to two.

For your given OS (Ubuntu?), figure out how BT works. Get a BT device (fully functional button or headset or something) and figure out how to discover it, then pair it, then use it, then unpair it, and see if it's discoverable again.

Then for this device, discover it, pair it, and see if the flashing changes from fast to slow. If so, it means the flashing tells you your paired state.

I'm looking at one device on Amazon that goes into AT mode when you push the button, if yours is the same, don't do that. Most BT devices go into pairing mode on a long press of the one true button, if yours is one of those, then try that.

Connect Tx to Rx on the BT device, and see if sending ASCII characters at it causes them to be echoed back to you. This has been previously suggested on this list.

Connect a USB to TTL Serial adapter to the Tx and Rx pins, press the button to put it in AT mode (if applicable), and change the baud rate to something compatible with your nanoVNA.

Etc, etc, etc. One step at a time, make sure it's working and you understand it's operation at each step before proceeding.

73, Willie N1JBJ