nRF52840 pin reset behaviour

[MKJ]

The datasheet appears to say that a pin_reset does not completely reset the chip:

in particular it does not reset the SWJ-DP interface which, I believe, in some circumstances leaves the debugger running and causes excessive current. This is referred to in this case:

https://devzone.nordicsemi.com/f/nordic-q-a/73447/the-nrf52832-did-not-halt-after-hardware-reset-pin-reset/303788

and this case:

https://devzone.nordicsemi.com/f/nordic-q-a/77812/nrf52840-current-consumption-increases-by-more-than-1ma-after-pin-reset-with-nrfjprog--p

I have two questions:

1) Is the table above correct because when we issue a soft reset from nrfjprog we do not get the extra 1ma which implies that SWJ-DP is being reset

2) Is it possible for the firmware to determine the state of SWJ-DP and, if necessary, disable it

Thank you,

Martin

[Simonr]

Hi again

Okay, so the current stays at the 1mA (debug current) after you call --pinreset, but not when --reset is called? A pin reset is not a "hard reset" per se. Only the power-on and brownout resets are considered "hard resets" as they reset all the target registers. --reset is also a soft reset that sets the SysResetReq bit of the AIRCR register of the core. The core will run after the operation.

Best regards,

Simon