Micro:bit v2 support

[heharkon]

Hi!

I purchased couple of BBC Micro:bits and seems that there's a new version, v2 of it, which I got then. It uses nrf52 instead of nrf51, so the existing board info for micro:bit doesn't match, I get

Board ID 9904 is not recognised, using generic cortex_m target. and then fail...

9900 and 9901 seem to be in the list for the first generation of Micro:bit.

I'm humbly asking would it be possible to support this version also? And if there's something I could help with, there might be a possibility to help. 😃 I do python, but I'm a total beginner with the boards etc. 😄

[flit]

Sorry… I have a partially implemented change but haven't had time to finish it. It's on my list.

Here's the branch: https://github.com/flit/pyOCD/tree/feature/microbit_v2
This has the board ID and a test binary.

The main thing missing is a built-in target for the nRF52833. If you'd like to help, you could duplicate the built-in nRF52840 target support and correct the memory map.

There is some general guidance for adding a new built-in target in adding_new_targets.md.

[heharkon]

Ok, and thanks for the quick reply!

Great to hear that it's cooking! I can take a look at that memory map, just not sure if I understand any of it, but otoh, I'm here to learn, so... 😄

[flit]

I'm happy to help with any questions you have.

[flit]

@heharkon Fyi, I added micro:bit v2 and builtin nRF52833 support on this branch of my fork: feature/microbit_v2.

If you have a chance, would you mind testing it?

You can install directly from this branch: pip install -U --pre git+https://github.com/flit/pyOCD.git@feature/microbit_v2

Thanks!

[flit]

Thanks!

[flit]

It looks like the failure is related to the Nordic SoftDevice and its protection.

First, I'm able to reproduce the failure you see with the firmware you attached above using pyocd flash -u9904 main.elf (I added the .elf extension myself).

Yet, I can successfully first perform a chip erase (pyocd erase -u9904 --chip) and then program the test binary at ./test/data/binaries/microbitv2.bin with default settings: pyocd flash -u9904 main.elf. However, the flash command after chip erase reports 34 pages skipped—this only happens when the data already in flash is the same as that being programmed. That should never be the case just after a chip erase (unless you are programming blank data, which is not the case here, double checked by examining the test file).

Those 34 pages that weren't erased almost certainly contain the SoftDevice.

When I either force pyocd to use sector erase, or use chip erase when I turn off the smart_flash option that controls the skipping of programming the same data, it fails as expected.

► pyocd flash -u9904 test/data/binaries/microbitv2.bin -esector -Osmart_flash=0 -Okeep_unwritten=0 -Odebug.traceback=0
[                    ]   1%0013955:CRITICAL:__main__:('erase_sector(0x0) error: 103', 0, 103)

► pyocd flash -u9904 test/data/binaries/microbitv2.bin -echip -Osmart_flash=0 -Okeep_unwritten=0 -Odebug.traceback=0
[                    ]   1%0013955:CRITICAL:__main__:('program_page(0x0) error: 103', 0, 103)

Right now I don't know how to work around it. The answer will require some investigation and reading of the nRF52 reference manual. It might require a mass erase using the nRF52's CTRL-AP, which will require some additions to pyocd (fortunately that I've already started).

[flit]

Umm, actually… I completely forgot that nRF52 mass erase is already supported in pyocd!

I was able to successfully program your test image by performing a mass erase (pyocd erase --mass) to wipe the SoftDevice, then programming as usual.

► pyocd erase -u9904 --mass
0005466:INFO:eraser:Mass erasing device...
0005676:INFO:eraser:Successfully erased.
► pyocd flash -u9904 var/devs/nrf52833/main.elf 
[====================] 100%
0005944:INFO:loader:Erased 4096 bytes (1 sector), programmed 4096 bytes (1 page), skipped 0 bytes (0 pages) at 10.44 kB/s

Once you remove the SoftDevice with the mass erase, you can program flash normally, until and unless you program an image that contains a SoftDevice.

[heharkon]

That worked, thank you very much!! 😃

[flit]

Glad to hear it. Thanks for helping me test!

[flit]

fyi: #1177

[flit]

micro:bit v2 support is integrated into version 0.31.0 of pyocd.