BBC micro:bit J-Link OB firmware for micro:bit v2.2

[NTNU_TTK4235]

Hello,

I am a research assistant at the Norwegian University of Science and Technology. We have in the past been using the micro:bit v1 and v2 for our practical labs which purpose is to introduce the students to basic C programming. For that, we have been using GCC ARM as our compiler, nrfjprog to flash compiled code to the micro:bit, and lastly JLink to communicate with the micro:bit. The latter removes the DAL by just simply drag and drop of the hex file from Segger.com.

Our problem is that for this year, we have received the second version of the micro:bit v2, namely the v2.2. I was therefore wondering if there is someone who could help or had experience with JLink on the new hardware. I tried to download the .hex file from https://www.segger.com/downloads/jlink/#BBC_microbit but I suspect that there is some hardware/software incompabilities from micro:bit v2 to v2.2.

Thank you so much in advance,

Best,

Kiet

[Hieu]

Hi Kiet,

I am not very familiar with the micro:bit boards, but I will try to support you. Could you please tell me more details? What are the symptoms that make you think there are some incompatibilities?

BR,

Hieu

[NTNU_TTK4235]

Hi Hieu,

Thank you so much in advance already!

In the past micro:bit (V1 and V2), JLink could be downloaded and installed on the board by simply downloading the .hex file from segger's website, and then drag-and-drop onto the board while it is in MAINTAINCE mode. Shortly afterwards, the board would reformat itself with JLink. This allowed us and the students to flash over .hex files to the micro:bit using .c code. A very quick method for verifying that JLink was successfully installed is through the commando 'nrfjprog -f nrf52 -e' which will prompt the micro:bit to rest by turning of the lights.

The main symptoms that make me suspect that there are incompatibilities are that dragging the JLink .hex file do not result in a restart when using the commando 'nrfjprog -f nrf52 -e'. Instead, we get something like this:

ERROR: No debuggers were discovered.

Best wishes,

Kiet

[Hieu]

Hi Kiet,

I think I get what is going on. To be completely sure, by JLink .hex from Segger's website, do you mean the firmware on this page?
www.segger.com/.../

I look into micro:bit schematic and interface documentation. There is a change in the interface MCU choice between V2.2, V2.0 and V1.x. The interface could be broken if you somehow flash the interface MCU with an incompatible firmware.

Looking at the download list on Segger's website, it is likely that they currently only have firmware for micro:bit V1.x, which uses a Freescale KL26, and for micro:bit V2.0, which uses a Freescale KL27.

Perhaps you could double check with Segger if that is correct? If so, you will need to wait for them to release a firmware for V2.2. 

Best regards,

Hieu