Blynk App and HM-10 are connected but it doesn't turn on LED


I have connected my HM-10 with the Blynk app but when I press the button the LED doesn’t turn on.

I’m using the default Blynk Example HM-10 and HC08.

Button #: D13

What could I try to do to make it work?


You could supply us more details to go on :stuck_out_tongue_winking_eye: e.g. Full code; Clarity of how you have wired the two devices; Confirmation of BT/BLE module using correct BAUD rate and being properly connected in the App, and so on…

Hi Gunner,

Thanks for your support.

I have to mention that the MH-10 is currently not connecting with Blynk anymore. It happened yesterday too, but today it connected right away and 15 min later it disconnected after I wrote to the Blynk Community. Is there a problem with the app?

The set up is:

  1. Arduino Uno
  2. YwRobot voltage converter
  3. Breadboard
  4. DSD Tech MH10
  5. I have also the HC-05 Bluetooth Board (brand new from today) but my Iphone does not seem to connect to it. Would the HC-05 work better? Can it be connected to my Iphone via Blynk app?
  6. LED light.


  1. MH-10:
  • GND to GND
  • VCC to 5V
    -TXD to D3
    -RXD to D2 note* (I have interchanged TXD and RXD but still does not work, and I have used TX-0 and RX-1 pins too but it didn’t work either)
    -LED to Pin D13 and GND



// You could use a spare Hardware Serial on boards that have it (like Mega)
#include <SoftwareSerial.h>
SoftwareSerial DebugSerial(2, 3); // RX, TX

#define BLYNK_PRINT DebugSerial
#include <BlynkSimpleSerialBLE.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "c1086626xxxxxxxxxxce193ab8675f";

void setup()
  // Debug console

  DebugSerial.println("Waiting for connections...");

  // Blynk will work through Serial
  // Do not read or write this serial manually in your sketch
  Blynk.begin(Serial, auth);

void loop()

Looking forward to some answers. Thanks again for the help.



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I suspect this is the root of your issue… as an Android user I can’t be positive, but I believe the iPhone only supports BLE, not BT.

And again!!! as has been mentioned to you in prior posts… the proper way to post code here is in the Welcome Topic (read the included link above) and was also described in the instructions you deleted when posting your topic… :wink: I have corrected your post.

Blynk - FTFC

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OK, I found more info on the other module you are using.

This should work… but I recommend you test it and your iPhone with some other non-Blynk app and process to be sure.

Definitely need to confirm that TX on one side goes to RX on the other, and vice versa… think from mouth to ear.

If you do this, then you need to use Serial, and not SoftwareSerial… changing all the code accordingly.

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OK, I think I see your other issue… you are not using the proper serial port for the proper uses at all :stuck_out_tongue:

The SoftwareSerial is the port for your Blynk connection… leaving the Serial port for Debug and programming.

Switch it around and try again… use this example to see how to do it.

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Thank you so much, you ppl are awesome.

I will let you know how it goes .



the problem came from the serial port. Now is working properly.

thank you for your help