I am writing a program for the nRF52805 for use in a battery-operated remote. It needs to wake up from sleep when any button is pressed, perform the interrupt (blinking an LED initially for debugging), and then go back to sleep. I'm trying to use a semaphore to control the flow of my interrupts and to tell when they are down so it can be put back to sleep. After performing the interrupt work, the program is intended to put the device to sleep using "sys_powroff()". When a button is pressed, an interrupt occurs, and it blinks an LED a number of times corresponding to the button number. When the part is asleep and a button is pressed, it gets to the k_sem_take function arrowed in the pic and halts, even though the interrupt should have run and performed a k_sem_give to release it past this line of code. If I press the button again while it is still hung up at the k_sem_take function, it then executes the interrupt work and shuts down as it should. Basically, if I hit a button twice in a row, then it blinks as it should.
Perhaps semaphores are not the best choice for this task? From what I've read, I can use one of these four methods:
1) Atomic Variable for Event Flag: Instead of relying on a semaphore, use an atomic variable as an event flag. The ISR can set this flag when a button is pressed, and the main loop can poll this flag to handle the event.
2) Interrupt-Driven State Machine: Design a state machine where the MCU transitions between states (e.g., IDLE, PROCESSING, SLEEP) based on events like button presses or timer expirations. The ISR updates the state, and the main loop processes the state changes.
3) k_poll Event Waiting Mechanism: Zephyr provides a k_poll API for event-driven programming. You can configure a k_poll_event structure to wait for an event (e.g., button press) and handle it in the main loop.
4) Use Direct Wake-Up and Sleep Logic: Use the wake-up configuration of the GPIO to handle sleep transitions directly. This can simplify the logic for entering and exiting sleep mode.
Which approach is recommended?
