I have a U80 Smartwatch from Bluetooth Watch International, which has bluetooth function. It is meant to be connected via to my smartphone (and it works perfectly).

I also have an Arduino Uno board and a corresponding BLE ZS-040 bluetooth chip.

I need for my smartphone to be able to detect my Arduino board, so I can send data from a simple circuit connected to the Arduino board to the smartphone.

Basically, my circuit is meant to be a simple push button. When the button is pushed, and the circuit is closed, the Arduino board will send a signal to the smartwatch. This will cause the smartwatch to ring and vibrate, as if it is receiving a call. Then to turn off the ringing and vibrating, the user can simply 'answer the phone call', and it will stop.

From what I understand, (I'm very new to Arduino) I have to connect the Arduino board to the smartwatch first, which means I have to somehow get the board to be detected by my watch, which it's not doing yet, eventhough the bluetooth module is connected to the board.

Then the push button needs to send a signal to the watch. Which means the command {if buttonpush='1', send (receiving call)}, so when the button is pushed, the signal is sent and the watch acts as if it is receiving a call. Basically showing all the physical signs (eg. vibrating and/or ringing based on the watch's setting, showing 'answer/deny call', etc.). Btw, the push button is not to be held down. As long is the button is pushed and released once, the signal should be sent, and the watch will buzz until the 'phone call' is answered or denied.

  1. I have absolutely no idea how to get the board connected to the smartwatch via bluetooth.
  2. And while I have a rough idea on the push button circuit I need, I also need to send the signal for the watch to act like it has received a call.

Mainly, I'm looking for any help with coding here. If anyone can help with the physical circuit connections, that would be awesome too.

  • What is your "corresponding bluetooth chip"?
    – Majenko
    Aug 29, 2017 at 11:58
  • Sorry, I have edited to add in the information. HC 05
    – ASH-Aisyah
    Aug 29, 2017 at 12:02
  • 2
    Unless the watch has a developer API for bluetooth (master) you can not use anything else than the Android app to connect to it properly even assuming you have a BTLE module.
    – Avamander
    Aug 31, 2017 at 13:23

2 Answers 2


HC-05 is a Bluetooth 2.1 SPP only chip (BR/EDR). Your bluetooth watch will be Bluetooth Low Energy 4.x (BLE Single Mode).

The two are not compatible.

You will need a BLE module for the Arduino which is capable of running as a "Central Device".

  • Thank you. I was a bit confused between the two, but I managed to confirm that mine is ZS-040 which is the BLE chip I think ><?
    – ASH-Aisyah
    Aug 29, 2017 at 12:15

This isn't exactly an answer but I will like to share my experience after attempting a similar project for the past week.

I have an Arduino UNO and a HM-10 Bluetooth module that is capable of functioning in central mode. I referred to http://www.martyncurrey.com/hm-10-bluetooth-4ble-modules to setup.

I am trying to connect the Arduino UNO/HM-10 with a Hexiwear (http://www.hexiwear.com) bluetooth IoT development smartwatch that is capable of sending sensor data such as steps, heartrate, temperature etc. via bluetooth to a BLE central device.

The Hexiwear will generate a random 6 digit pin when you attempt to connect to it. It works with its own companion Android app and reads sensor data perfectly. Someone managed to pull in the hexiwear's sensor data to a Raspberri Pi via BLE here: https://mcuoneclipse.com/2016/12/19/tutorial-ble-pairing-the-raspberry-pi-3-model-b-with-hexiwear/comment-page-1/#comment-97375.

With my Arduino UNO, I managed up to the point were I could connect the hexiwear and it pops up to ask for the random 6 digit pin so that it could pair to my Ardunio.

And then I am stuck, because I know nothing about the Arduino UNO and HM-10 that can send the pin code back to the Hexiwear.

Here's where I thought might be useful:

1) Do you have the U80's BLE specifications. This is how much hexiwear's BLE specification looks like https://github.com/MikroElektronika/HEXIWEAR/blob/master/documentation/HEXIWEAR%20Bluetooth%20Specifications.pdf.

My Hexiwear wearable comes with source code. If I try hard enough I can probably hack it to make what I want to do possible.

2) Does U80 require pairing with pin code? I am stuck here in my project.

3) Is the library for your BLE chip capable to sending said BLE requests and responses to communicate with the U80? This is where I believe I am going to be stuck further.

Hope this helps in some ways.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.