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Topic: JY-MCU Pairing but can't get it to work (Read 1 time) previous topic - next topic


I recently bought a jy mcu from ebay. I upload the code onto my nano via usb first, then plug bt module on. The module starts flashing.
I managed to pair it and it shows up to be linvor on COM9.

However, when I go to device manager, there are two COM ports that are bluetooth. COM9 and COM10.

When I use the arduino ide to use the serial monitor, I can only see COM10 and COM10 doesn't work.
I've tried using putty, and putty CANNOT CONNECT TO COM9!

What's wrong?



For starters, don't try using the IDE serial monitor for bluetooth.  You might try RealTerm instead of Putty. I find it works fine

I have noticed that when I pair it to the pc, the module still flashes.
Is that supposed to happen?


The manuals are unintelligible.

No action = fast flash
Programme mode = slow flash c. 1Hz (I think)
Kosher connection = steady 

My bluetooths do exactly what I want, and reliably, which is send data to my laptop. Having said that, my desktop can't see them, and my tablet can but refuses to listen.

Note that JY-MCU only refers to the backplane. The actual modules are HC-05 and HC-06 they are difficult, or impossible, to tell apart.

I have managed to get it to have a steady light now. However, I can't send any data to or from.


OK, a steady light implies a kosher connection. I don't know what your problems are but they are probably not serious and there are a couple of (linked) traps for young players you might not be aware of.

1. The serial monitor clashes with bluetooth i.e. the operations for both are the same. If you are using the USB cable for power, get rid of it and use the wall wart. If you haven't got a wall wart, aquire one immediately, you can be sure you will need it more and more. While you are waiting, get your USB power from another computer.

2.   Because the operations are the same, so is the programming. Specifically, if you can send data to the serial monitor, you have done all you need at the Arduino end to send data via Bluetooth. Serial.print.  No more programming, all the work is now at the  Windows end. You need to trawl for bluetooth, I guess you have done that, identify the COM port, and advise RealTerm of the port and rate. I have those parameters saved in RealTerm and simply start it from a desktop icon.

I am only interested in one-way traffic but I understand sending commands to Arduino via Bluetooth is the same as doing it from serial monitor and there is a facility in RealTerm for that purpose.

Note that, despite the clash, or because of it, you can send identical information simultaneously via serial to one computer and via Bluetooth to another, which can be quite useful!

Also note that it is possible to have a device pair but refuse to communicate. I have had this happen with my Android tablet but I'm afraid I can't recall what the LED does. I have never pursued this as I have a real computer that is just about as convenient, and works.

I have tried all you said. However, I was using a nano. I'm now using a mega to see if there's any difference.

My power does not come from a usb and I've tried putty, realterm and hyperterminal. All of these can connect and results in a constant light but none show and thing that I send.

my program:

void setup()
void loop()

I have got it. Connected tx rx wrong way round.



Aha, LoL.

I believe the common third trap for young players is that the Bluetooth can pair and connect once the power is up.  No connection, kosher or otherwise, to your Arduino  is actually needed for this. The Arduino merely sends or acquires data through it.

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