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This article mainly explains "the method of judging the interrupt state of FreeRTOS software timer apollo". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Next let the editor to take you to learn the "FreeRTOS software timer apollo interrupt state judgment method"!

Problem scenario

In the development, it is found that the FreeRTOS software timer does not work, which is specifically reflected in the fact that the software timer can not be interrupted.

Analyze the problem

It is found that only during the execution of a task, the software timer of FreeRTOS will not work, and other tasks will be executed normally. After troubleshooting, the priority of this task is higher than that of the timer task, and it takes a long time, so that the task can not be cut out.

Solve the problem

Modify timer task priority to the highest priority in FreeRTOSConfig.h to solve the problem

Apollo interrupt state judgment

When I look at the apollo3 code, I find the following function

Void WsfSetOsSpecificEvent (void) {if (xRadioTaskEventObject! = NULL) {BaseType_t xHigherPriorityTaskWoken, xResult; if (xPortIsInsideInterrupt () = = pdTRUE) {/ / Send an event to the main radio task xHigherPriorityTaskWoken = pdFALSE; xResult = xEventGroupSetBitsFromISR (xRadioTaskEventObject, 1, & xHigherPriorityTaskWoken) / / If the radio task is higher-priority than the context we're currently / / running from, we should yield now and run the radio task. / / if (xResult! = pdFAIL) {portYIELD_FROM_ISR (xHigherPriorityTaskWoken);}} else {xResult = xEventGroupSetBits (xRadioTaskEventObject, 1); / If the radio task is higher priority than the context we're currently / / running from, we should yield now and run the radio task. / / if (xResult! = pdFAIL) {portYIELD ();}

This is FreeRTOS sends an event flag group, xPortIsInsideInterrupt this function to determine whether the interrupt, and then call to determine whether to call api at the end of FromISR, let's take a look at the principle

Static portFORCE_INLINE BaseType_t xPortIsInsideInterrupt (void) {uint32_t ulCurrentInterrupt;BaseType_t xReturn; / * Obtain the number of the currently executing interrupt. * / _ _ asm {mrs ulCurrentInterrupt, ipsr} if (ulCurrentInterrupt = = 0) {xReturn = pdFALSE;} else {xReturn = pdTRUE;} return xReturn;}

Read the IPSR register, 0 indicates that there is no interrupt running, and non-0 indicates the running interrupt number, that is, it is in the interrupt, so use the api ending with FromISR

At this point, I believe that everyone on the "FreeRTOS software timer apollo interrupt state judgment method" have a deeper understanding, might as well to the actual operation of it! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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