task is blocked

[aslansq]

introduction-to-rtos/11-priority-inversion/esp32-freertos-11-solution-critical-section/esp32-freertos-11-solution-critical-section.ino

Line 102 in f2ae379

while ( (xTaskGetTickCount() * portTICK_PERIOD_MS) - timestamp < cs_wait);

Hello
Thank you very much for all these great tutorials. Maybe this stupid question but here it goes:

I thought OS systick also interrupt based. When I run this code in QEMU, ofc it stops in this line forever since systick is never increased. Is this a bug? Sorry I dont have hardware to test it.

[aslansq]

https://github.com/aslansq/freertos_intro_qemu

I dunno if you care to look at it :) but I implement all of your tutorials in qemu vanilla freertos.

[ShawnHymel]

Awesome work! I linked to your repo from the README to hopefully help people who don't have the hardware.

I don't know QEMU, but my guess is that the appropriate ISR is not implemented. In your code xPortSysTickHandler is declared but never defined (from what I can tell).

It also might be related to the SysTick_Handler vs. xPortSysTickHandler naming issue in ARM CMSIS: FreeRTOS/FreeRTOS-Kernel#511

Sorry I don't have more info...maybe those links are helpful?

[aslansq]

Ah thank you! I ll put some more effort to clean it up
I am confused now though. If there is no 'taskENTER_CRITICAL', ISR gets called.

When there is 'taskENTER_CRITICAL', ISR does not get called. xTickCount is always 25.

Isn't 'taskENTER_CRITICAL' should disable all interrupts?

[ShawnHymel]

That is weird it is stuck at 25. You are correct: taskENTER_CRITICAL should disable interrupts: https://www.freertos.org/Documentation/02-Kernel/04-API-references/04-RTOS-kernel-control/01-taskENTER_CRITICAL_taskEXIT_CRITICAL

[aslansq]

Anyways, I am surprised it worked for you.
aslansq/freertos_intro_qemu#27
I fixed mine like this.
since it works for you, I am closing the issue.

[ShawnHymel]

I actually haven't had a chance to try it yet. Did you manage to get it working?

[aslansq]

Yes but in a different way. I described below how. I hope it is clear and helps :)

Description of the bug at my setup:

xTaskGetTickCount returns xTickCount. xTickCount is increased by systick timer interrupt. Since we disabled all interrupts, xTickCount never changes.

My workaround:

I have setup a new timer with huge prescaler and does not depend on interrupt.

Instead of xTaskGetTickCount I use: