xQueueReceive failing with corruption

[blondguy (Alan Nilsson)]

@jefftenney

I think I found the problem. In your FreeRTOSConfig.h, configLIBRARY_LOWEST_INTERRUPT_PRIORITY is set to 8. It should be 7. It should always be (1 << configPRIO_BITS) - 1.

Using 8 is causing the PendSV interrupt to have priority 0, the highest priority in the system. To work correctly, PendSV must be configured for the lowest priority in the system.

I think we have a winner here. Going on 2 hours of run time, I’ll check back in the AM

[rtel (Richard Barry)]

Nice one @jefftenney - I looked and didn’t even notice that.

@blondguy - please let me know if configLIBRARY_LOWEST_INTERRUPT_PRIORITY was something you set manually, or if it was set automatically by the tools. Thanks.

[blondguy (Alan Nilsson)]

We do indeed have a winner. Thank you Jeff & Richard, the level of support you gave me surpassed what I expected. It gives me confidence in my choice of FreeRTOS!

As to your last question Richard, I think that value came from an example blinky project from NXP that an intern used for the initial creation of this code.

Once again, thank you both!

[blondguy (Alan Nilsson)]

@jefftenney

I think I found the problem. In your FreeRTOSConfig.h, configLIBRARY_LOWEST_INTERRUPT_PRIORITY is set to 8. It should be 7. It should always be (1 << configPRIO_BITS) - 1.

Using 8 is causing the PendSV interrupt to have priority 0, the highest priority in the system. To work correctly, PendSV must be configured for the lowest priority in the system.

Question: Is there a reason to even offer this configuration if should always be based off of configPRIO_BITS?

[jefftenney (Jeff)]

Seems to me that both configLIBRARY_LOWEST_INTERRUPT_PRIORITY and configPRIO_BITS are useful symbols, and FreeRTOSConfig.h is a good home for them. That leaves the application developer responsible for making sure they agree with each other, with help from sample applications and/or tool-generated projects.

However, configKERNEL_INTERRUPT_PRIORITY (another symbol from FreeRTOSConfig.h) should maybe not control the PendSV priority after all. It should probably control the Systick priority only.