AM2434: MCU-PLUS-SDK-AM243X: R5F Interrupt priorities and interrupt nesting

Johannes von Löwis

Part Number: AM2434
Other Parts Discussed in Thread: SYSCONFIG

In my application running on R5F_0_0 I have two interrupts:

One 16 kHz interrupt triggered by ADC0 (which is started by an EPWM-SOC) and a 1 kHz interrupt from TIMER0.

I wish the TIMER0 ISR to be interruptable by the ADC ISR. How would I achieve that?

It seems that interrupt priorities (given in Sysconfig for TIMER0 ISR and passed to HwiP_construct() for the ADC ISR) don't do the job no matter how I set them.

My application is using RTOS but for now I'm not making much use of RTOS functionality. It is essentially using freertos_main() task from the hello world example to execute the former bare metal code that initializes peripherals and interrupts and eventually enters a main-loop.

Best regards,

Johannes

over 3 years ago

0 Frank Livingston over 3 years ago

TI__Mastermind 29338 points

Hi Johannes,

For FreeRTOS, nested interrupts are disabled. Please see Please see "Features Not Supported" here: https://software-dl.ti.com/mcu-plus-sdk/esd/AM243X/08_02_00_31/exports/docs/api_guide_am243x/KERNEL_FREERTOS_PAGE.html#autotoc_md324

Regards,
Frank

0 Johannes von Löwis over 3 years ago in reply to Frank Livingston

Expert 1806 points

Hi Frank,

thank you for your response. Is there hope that the mentioned "issues in some corner cases" that appear to prevent interrupt nesting to work will be fixed in the not so far future?

BTW, in many of the example linker command files the comment

/* This is the size of stack when R5 is in IRQ mode
* In NORTOS,
* - Here interrupt nesting is disabled as of now
* - This is the stack used by ISRs registered as type IRQ
* In FreeRTOS,
* - Here interrupt nesting is enabled
* - This is stack that is used initally when a IRQ is received
* - But then the mode is switched to SVC mode and SVC stack is used for all user ISR callbacks
* - Hence in FreeRTOS, IRQ stack size is less and SVC stack size is more
*/

indicates that interrupt nesting is enabled in FreeRTOS.

Best regards,

Johannes

0 Frank Livingston over 3 years ago in reply to Johannes von Löwis

TI__Mastermind 29338 points

Hi Johannes,

Johannes von Löwis said:
Is there hope that the mentioned "issues in some corner cases" that appear to prevent interrupt nesting to work will be fixed in the not so far future?

I'm following up with internal experts on this. I'll get back with you when I know more.

Johannes von Löwis said:
BTW, in many of the example linker command files the comment

Thanks for the feedback. This directly contradicts the documentation! I'll file a bug to have this corrected.

Regards,
Frank

0 Frank Livingston over 3 years ago in reply to Johannes von Löwis

TI__Mastermind 29338 points

Hi Johannes,

I consulted internally, and was informed there is currently no plan to add support for R5F nested IRQs for FreeRTOS.

I've filed a request to have the feature added, and to add more explanation for the "corner cases" mentioned in the documentation.

Regards,
Frank

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AM2434: MCU-PLUS-SDK-AM243X: R5F Interrupt priorities and interrupt nesting