topic Re: S32K146 RCM_SRS Register value for SWD reset in S32K

S32K146 RCM_SRS Register value for SWD reset

adria — Fri, 15 Nov 2019 16:16:03 GMT

Hello,

When I perform a software reset by calling "SystemSoftwareReset()" I read SW (bit 10) as reset cause int the RCM_SRS register. That is perfect.

But when I perform a reset through SWD from the IDE (S32 Design Studio) I am getting the same reset cause.

Is that the correct behaviour?

I can see there is a bit field in the RCM_SRS register for a reset caused by JTAG, shouldn't this be the one active when the reset is caused by SWD?

Thanks in advance!

Best regards,

Adria

Re: S32K146 RCM_SRS Register value for SWD reset

danielmartynek — Tue, 19 Nov 2019 14:51:11 GMT

Hello Adria,

What debugger are you using?

Have you tried resetting the MCU while running an empty project?

The JTAG flag is set only if the debugger selects a certain IR codes.

But the debugger can reset the MCU using external reset pin as well.

BR, Daniel

Re: S32K146 RCM_SRS Register value for SWD reset

adria — Tue, 26 Nov 2019 19:11:37 GMT

Hi Daniel,

I am using Segger J-Link. When I perform the reset through the IDE (S32 Design Studio) I get a Software reset, and this bit says:

"Software
Indicates a reset has been caused by software setting of SYSRESETREQ bit in Application Interrupt and
Reset Control Register in the Arm core.
0 Reset not caused by software setting of SYSRESETREQ bit
1 Reset caused by software setting of SYSRESETREQ bit"

Instead, when I use PE Micro Multilink Universal as debugger, I get External Reset Pin, and this bit says:

"External Reset Pin
Indicates a reset has been caused by an active-low level on the external RESET (RESET_b) pin.
0 Reset not caused by external reset pin
1 Reset caused by external reset pin"

This last one (with Multilink debugger) makes more sense for me because the debugger can write on the MCU reset pin and so cause a reset through that pin. But in the case of the J-Link debugger, it just felt weird that a reset cause by a user through the debugger triggers a Software reset, which normally is done programmatically from the code.

The only thing I would like to know if it all makes sense?

Best regards,

Adria

Re: S32K146 RCM_SRS Register value for SWD reset

danielmartynek — Wed, 27 Nov 2019 15:03:16 GMT

Hi Adria,

Yes, it makes sense.

Please refer to J-Link / J-Trace User Guide

https://www.segger.com/downloads/jlink/UM08001

7.10 Reset strategies

7.10.2 Strategies for Cortex-M devices

Thanks,

BR, Daniel

Re: S32K146 RCM_SRS Register value for SWD reset

adria — Wed, 27 Nov 2019 16:31:55 GMT

Hi Daniel,

Thanks!

Best regards,

Adria