minimum Pin requirement for KL03Z

[benoitverdin]

Hi, I'm using the KL03Z MCU for one of my project. As space is very limited on the board, i want to keep pin count to a minimum.

So my question : is it possible to program the MCU using only VCC, GND, SWDIO and SWCLK pins? I have seen that FRDM boards and OpenSDA use reset line for Debug and does not seem to work without it connected. Any idea which debugger i could use working with the minimal SWD configuration specified in de documentation : "2-pin serial wire debug (SWD) provides external debugger interface" found here

regards,

Ben

[BlackNight]

Hi Ben,

the reset is needed to my understanding to halt the CPU and to talk to it out of power-on reset. Otherwise the debug interface might not be able to halt the core our of reset and talk to it. That's especially a need if going into low power mode or if you decide later to use the SWD pins for other purposes.

Erich

[benoitverdin]

Hi Erich,

Thank you for your reply. So debug is not possible without reset line... I don't get why they call SWD "two-pin serial wire debug"...

But is flash programming with Seger/PE/Cyclone/etc possible if SWD are no used for other purpose?

regards,

Ben

[BlackNight]

Hi Ben,

it *is* possible to debug the device with SWD only. All what I say that without the reset line you might be able to halt the processor through the debug interface to stop it in order to talk to it.

Erich

[BlackNight]

Hi Ben,

to add this this, you might fine Bricking and Recovering FRDM-KL25Z Boards: Reset, SWD Clock and Low Power | MCU on Eclipse  useful in that context. That's why in my board designs I always make the reset pin available to the debug interface.

Erich