MPC5746R User Mode Machine Check Exception on Accessing SIUL2 ports

[David_Swain]

Good Afternoon

I am attempting to run application code in USER mode but every time I attempt to write to an SIUL2 port register I get a machine check error. 

The OS is relatively simple and accesses the application through a jump block after setting up the base system for the application to run (I hope). No memory protection blocks are changed from their default values except the AIPS which (for now) I have set to maximum permissions (everything is usable by everyone) but I still get a machine check exception each time I try to initialise an SIUL2 port. I have no issues with the DSPI block or the TPU blocks so I don't think it is a general peripheral issue.

I have attached what I hope are the relevant parts of the OS and application, I apologise it is so little but I had to fight to be able to send this.

The two OS files attached are the relevant startup code and the OS code is the first file the application runs when initialising.

Any suggestions or better yet absolute answers would be much appreciated.

[petervlna]

Hello,

I expect that the issue is in register protection. As you can see SIUL is protected, but DSPI or eTPU are not.

You need to allow access in user mode to SIUL module registers in register protection.

Set UAA bit for SIUL to 1.

Best regards,

Peter

[David_Swain · Accepted solution]

Peter

Thanks for the quick response. Chapter 80 took some figuring out but in the end I managed to get my head around what it was saying and implemented you suggestion and this works fine.

Regards

David