Long story short: I need to pair these devices:

  • Arduino UNO with Seeed BLE Shield
  • Adafruit Feather 32u4 Bluefruit LE.

The Seeed shield is configured and able to connect and communicate via the UART to an Android phone by HM BLE Terminal app from Google Play Store.

I can also connect the phone and Feather. The two independent connections work really well but a problem occurs when connecting the Seeed shield with Feather. Connection isn't troubling No errors are reported but I can't send/receive any data via the serial monitor (I'm using bleuart_cmdmode or bleuart_datamode from the Adafruit examples).

Basically my question is how to make them work: HM-11 module with BLE and the Adafruit board (nRF51822 chipset from Nordic).

1 Answer 1


Although the nRF51822 supports Central (master) mode, the Adafruit Feather's firmware only support's Peripheral (slave) mode.

The Bluefruit LE firmware from Adafruit is currently peripheral only, and doesn't run in Central mode, which would cause the module to behave similar to your mobile phone or BLE enabled laptop.

At some point we might consider a new firmware image offering this, but since 98% of the uses cases for BLE involved running as a peripheral we've concentrated all of our development effort there for now.


The HM-11 on your Seeed shield is capable of Central (master) mode though. This means your Uno will play the part that your Android phone was playing when you connected the Feather to the terminal app.

To set your HM-11 to Central mode, run the following AT command.


Example code for the HM-11

Alternatively, you could burn the S120 Soft Device and your own custom firmware onto the Feather's nRF51822. You can find all the docs, tools, and Soft Device images on Nordic's website.

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