RE: RM48 FreeRTOS, taskDelay() SCI DMA problem

FinleyQ

Other Parts Discussed in Thread: RM57L843

Dear Anthony,

I have some problrm at using FreeRTOS with SCI DMA.

I use RM57L843.

When I not use RTOS, I can use DMA send or receive SCI data very well. But when I use FreeRTOS, there goes a problem. I have two tasks in my system, when I call function dmaSetChEnable(DMA_CH2, DMA_HW) in my task , the system stoped at HL_sys_intvecs.asm -> interrupt vectors -> dataEntry . It seems cannot write to DMA register HWCHENAS. I cannot understand this problem.

Can you give me some suggest for this? I am anticipating your reply. Thank you.

Best Regards,

Finley Quan

over 9 years ago

0 Anthony F. Seely over 9 years ago

TI__Guru 68950 points

Finley,

Hi. Sorry for the delay, just saw your post.

I split this to a separate thread. If you post a question on a thread already answered/closed it can get lost so it's better to post to a new thread. You can always paste a hyperlink to the other thread and say you think you have the same issue.

This register only be written if the CPU is in privilege mode. Notice the (-WP-) type in the bit description.

You are likely trying to access this bit from a task that is not running with privilege (in user mode) and this is causing the data abort.

In that case the solution is to create a privileged task that manages the DMA controller.

0 FinleyQ over 9 years ago in reply to Anthony F. Seely

Prodigy 80 points

Hi Anthony,

Thanks of your answer and suggestion.
Um...But how can I creat a privileged task, I have no idea about this. Any instruct from you may be helpful.
Thanks a lot.

Best Regards,
Finley Quan.

0 Anthony F. Seely over 9 years ago in reply to FinleyQ

TI__Guru 68950 points

Hi Finley,

You have to read the FreeRTOS manual, there is a new version of the task create function that allows you to create a task with privilege.

0 Anthony F. Seely over 9 years ago in reply to Anthony F. Seely

TI__Guru 68950 points

See www.freertos.org/FreeRTOS-MPU-memory-protection-unit.html

"Tasks created using xTaskCreateRestricted() can also be created to execute in either Privileged mode or User mode - but this time User mode tasks have access to their user defined memory regions in addition to their stack. A Privileged mode task can call portSWITCH_TO_USER_MODE() to set itself into User mode. A task that is running in User mode cannot set itself into Privileged mode."

0 FinleyQ over 9 years ago in reply to Anthony F. Seely

Prodigy 80 points

Hi Anthony,

I will read this part later, and create a task with privileged mode.
Thank you!

Best Regards,
Finley Quan.

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RE: RM48 FreeRTOS, taskDelay() SCI DMA problem