FreeRTOS - Interrupt Management
You have two ISRs: ISR_A (priority 3) and ISR_B (priority 5). ISR_A uses a FreeRTOS API function that disables interrupts up to priority 4. What happens if ISR_B triggers while ISR_A is running?
You have two ISRs: ISR_A (priority 3) and ISR_B (priority 5). ISR_A uses a FreeRTOS API function that disables interrupts up to priority 4. What happens if ISR_B triggers while ISR_A is running?
hard📝 Application Q8 of 15
Step-by-Step Solution
Solution:
Step 1: Understand interrupt masking by FreeRTOS API
FreeRTOS disables interrupts up to priority 4 during some API calls, blocking lower priority interrupts.Step 2: Analyze ISR priorities
ISR_B has priority 5, which is lower than 4, so it is masked and delayed until ISR_A finishes.Final Answer:
ISR_B will be delayed until ISR_A finishes -> Option BQuick Check:
Interrupts below mask priority are delayed [OK]
Quick Trick: FreeRTOS masks interrupts below certain priority during API calls [OK]
Common Mistakes:
- Assuming lower priority ISR preempts higher priority ISR
- Thinking ISRs run simultaneously
- Believing ISR_B disables ISR_A
Master "Interrupt Management" in FreeRTOS
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