Arduino Nano 33 BLE

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This article describes how a J-Link probe can be used together with an Arduino Nano 33 BLE board.

Minimum requirements

Preparing for J-Link

The Arduino Nano 33 BLE board does not come with an external debug interface connector, but the required connections are exposed on the back side on test points as follows:

Nano33 BLE Close.png

To these test points flying wires can be soldered which then can be connected to the J-Link input pins. For this example we used the .1" 20-pin ribbon cable that is shipped with each J-Link that offers that 20 pin input type and cut it in half. Now the necessary cables just need to be stripped and can be soldered to the test points. The following table describes the pinning and how it should be connected to the J-Link 20-pin input.

Arduino Board J-Link 20-pin input
1 nRESET (pin 15)
2 GND (pin 4)
3 SWCLK (pin 9)
4 VTREF (pin 1)
5 SWDIO (pin 7)

In this example we are using a J-Link Plus Compact. The resulting connection will then look like this:

Nanoe33 BLE Wired.png

  • Power the board via the USB-Mini port
  • Verify the Connection with e.g. J-Link Commander. The output should look as follows:

nano33 BLE Connect.png

Debugging with Arduino tool chain

Generally there is two ways to debug a Arduino sketch with J-Link. Both variants are explained below.

Direct debugging of the Arduino sketch

How to debug your Arduino sketch directly is explained here: How_to_debug_an_Arduino_Sketch_with_Ozone_and_J-Link

Indirect debugging of the Arduino sketch

Generally we recommend the direct debug approach as shown above. But if for some reason you can't use that method you can still debug as follows.

  • Connect your board to a J-Link as explained above and test the connection with J-Link Commander.
  • Download your Arduino Sketch with e.g. Arduino IDE via the USB-Interface as usual.
  • Now you can launch your favorite debugger with J-Link and attach to the running application and debug your system.

We recommend using Ozone, the J-Link debugger as it offers the best debug experience with SEGGER debug probes. You can set Ozone to attach to the target device via Debug->Start Debug Session->Attach to Running Program.

Bare-metal Debugging

Example project for SEGGER Embedded Studio

The following example project was created with the SEGGER Embedded Studio project wizard and runs out-of-the-box on the Arduino Nano 33 BLE board. It is a simple Hello World sample and can be downloaded here: Hello World sample

Note: Using this example project will erase the Arduino bootloader and allow bare-metal debugging of the target device. If you want to revert the Arduino board to its original state you need to flash the Arduino bootloader of the corresponding board you are using. For this the now established connection between your J-Link and the board can be used.

Bootloader sources can be found here:

As a tool we recommend using J-Link Commander where you can use commands loadfile/loadbin to flash the bootloader file. If the bootloader for your board should not be available you can simply dump it into a binary file also using the J-Link Commander and the command savebin. For more information see our J-Link user manual.