Become a leader in the IoT community!

New DevHeads get a 320-point leaderboard boost when joining the DevHeads IoT Integration Community. In addition to learning and advising, active community leaders are rewarded with community recognition and free tech stuff. Start your Legendary Collaboration now!

Step 1 of 5

CREATE YOUR PROFILE *Required

OR
Step 2 of 5

WHAT BRINGS YOU TO DEVHEADS? *Choose 1 or more

Collaboration & Work 🤝
Learn & Grow 📚
Contribute Experience & Expertise 🔧
Step 3 of 5

WHAT'S YOUR INTEREST OR EXPERTISE? *Choose 1 or more

Hardware & Design 💡
Embedded Software 💻
Edge Networking
Step 4 of 5

Personalize your profile

Step 5 of 5

Read & agree to our COMMUNITY RULES

  1. We want this server to be a welcoming space! Treat everyone with respect. Absolutely no harassment, witch hunting, sexism, racism, or hate speech will be tolerated.
  2. If you see something against the rules or something that makes you feel unsafe, let staff know by messaging @admin in the "support-tickets" tab in the Live DevChat menu.
  3. No age-restricted, obscene or NSFW content. This includes text, images, or links featuring nudity, sex, hard violence, or other graphically disturbing content.
  4. No spam. This includes DMing fellow members.
  5. You must be over the age of 18 years old to participate in our community.
  6. Our community uses Answer Overflow to index content on the web. By posting in this channel your messages will be indexed on the worldwide web to help others find answers.
  7. You agree to our Terms of Service (https://www.devheads.io/terms-of-service/) and Privacy Policy (https://www.devheads.io/privacy-policy)
By clicking "Finish", you have read and agreed to the our Terms of Service and Privacy Policy.

Modifying FreeRTOS Interrupt Priorities After Scheduler Initialization

Hey everyone @Middleware & OS , I’m neck-deep in an RTOS project using FreeRTOS. I need to read and potentially modify interrupt priorities after the FreeRTOS scheduler has been kicked off with `vTaskStartScheduler()`. The issue is, `NVIC_GetPriority(DMA1_Channel4_IRQn)` seems to behave differently depending on when I call it.

#include <FreeRTOS.h>
#include <queue.h>
#include <task.h>
#include "stm32f4xx_hal.h" 

static void vTest_NVIC(void *pvParameters) {
    tprintf("rnTask Started...");

    while (1) {
        taskENTER_CRITICAL(); 
        uint32_t priority = NVIC_GetPendingIRQ(DMA1_Channel4_IRQn) ?
                             NVIC_GetPriority(DMA1_Channel4_IRQn) : portMAX_DELAY;
        tprintf("rnCurrent priority (if pending): %d", (int)priority);
        taskEXIT_CRITICAL();
        vTaskDelay(pdMS_TO_ICKS(3000)); 
    }
}

int main(void) {
    portBASE_TYPE xReturn;
    HAL_NVIC_SetPriorityGrouping(NVIC_PRIORITYGROUP_4); 
    HAL_NVIC_SetPriority(DMA1_Channel4_IRQn, 11, 0); 
    tprintf("rnInitial priority: %d", (int)NVIC_GetPendingIRQ(DMA1_Channel4_IRQn) ?
    NVIC_GetPriority(DMA1_Channel4_IRQn) : portMAX_DELAY);
    vTaskStartScheduler();
}

– Before calling `vTaskStartScheduler()`, `NVIC_GetPriority(DMA1_Channel4_IRQn)` works as expected and reflects the configured priority (11).
– However, after the scheduler starts, the function consistently returns 11, regardless of any changes I try to make within the `vTest_NVIC` task.
I’ve tried using `taskENTER_CRITICAL()` and `taskEXIT_CRITICAL()` to ensure thread safety, but it doesn’t seem to resolve the issue.
What am I missing here? Why does the behavior differ before and after the scheduler starts?

Browse other Product Reviews tagged

Leaderboard

RANKED BY XP

All time
  • 1.
    Avatar
    @Nayel115
    1620 XP
  • 2.
    Avatar
    @UcGee
    650 XP
  • 3.
    Avatar
    @melta101
    600 XP
  • 4.
    Avatar
    @lifegochi
    250 XP
  • 5.
    Avatar
    @Youuce
    180 XP
  • 6.
    Avatar
    @hemalchevli
    170 XP