Kinetis MicrocontrollersのトピックRe: Decode BusFault address for k82

Decode BusFault address for k82

EugeneHiihtaja — Thu, 21 Jun 2018 17:30:37 GMT

Hello !

I have used sysmpu example for investigate how MPU detect acceses to protected area.

I can see BusFault handler code is detect exact address, access to what cause fault and from what slave it arrive.

But if access issued for peripheral area (0x40000000 - 0xFFFFFFFF), BusFault is occurs but code is show that no any slave errors at all.

How to detect exact fault address in case when wrong access is issued to peripheral area ?

MPU in K82 covers real memory and partially ( or all ?) peripheral area but ecat address are not decoded.

By the way could you recommend some guide/app note where explained how-to detect information from major ARM fault exeptions ?

Regards,

Eugene

Re: Decode BusFault address for k82

jingpan — Tue, 26 Jun 2018 06:30:12 GMT

Hi,

peripheral space(from 0x40000000) is not protected by MPU. It is protected by AIPS-Lite itself. The default setting of AIPS-lite prevent unprevilege access. Unlike MPU, AIPS-Lite does not record exact fault address. If you have an operation system, you can know which process/thread cause BusFault. Then you have to check the current stack to get the exact address. If you only want to know the address during debug, you can see it in debug window.

It seems there is not any application notes for MPU and AIPS-Lite. If you want to know more detail about ARM's exception mechanism, please see DDI0403D_arm_architecture_v7m_reference_manual and DDI0439B_cortex_m4_r0p0_trm.

Regards,

Jing