PyOCD Hardware Reset

jfc

Hi,
I’m working on a provisioning script that loads a piece of firmware and then interacts with it over a UART. I am using the PyOCD API and the firmware load works just fine. However, I need to reset the MCU before starting the serial port interaction. My tests show that I need to get the same effect as pushing the RST button on the Feather before proceeding with the serial port part of the system.

I have tried several reset types from both from the command line and the provisioning script (API):
API: target.reset(target.ResetType.HW)
and
command line: pyocd reset -m hw -t nrf91

If I reset the Feather manually, all is good. But I need to do it via the API.

FWIW I’m using the Raspberry Pi debug probe for both SWD and UART and so far, so good, except for this reset issue.

I’m sure I have not provided all the key details but thanks for any help!
Jim

jaredwolff

Have you tried it with probe-rs / nrfjprog / jlinkexe to see if you get a difference?

You may some helpful info in the programming guidelines: https://docs.nordicsemi.com/bundle/nan_041/page/APP/nan_production_programming/intro.html

jfc

Hi Jared,
Thanks for the reply. Have not installed probe-rs. nrfjprog does not see the probe and don’t seem to have jlinkexe.

After some dinking this morning I was able to reliably reset via pyocd:

$ pyocd commander -c “set reset-type system ; reset” -t nrf91
0001274 W Skipping CoreSight discovery for AHB-AP#1 because it is disabled [ap]
Resetting target

But multiple efforts with the API failed, including
target.reset(target.ResetType.SW_SYSTEM)
target.reset(target.ResetType.SW_SYSRESETREQ)

and
session.options[‘reset_type’] = ‘system’
target.reset()

One of them actually hangs indefinitely.
So for now, I’m doing this:
result = subprocess.run([“pyocd”, “commander”, “-x”, “reset.cmd”, “-t”, “nrf91”], capture_output=True, text=True)
Which is working.

Would be nice to keep this with the API, consistent with all the other interactions with the device.
Jim