Hello, I am currently trying to implement os_tick_idle for the pic32mz2048efg100 of the wifire board.
I looked at other implementations, especially the one for nrf51xxx. It seems that on ARM cortex M processors, interrupts are still able to wake up the cpu even if the "cspid i" instruction (disabling interrupts in OS_ENTER_CRITICAL) was executed before (source: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka16222.html) However this approach does not work on PIC32. Interrupts cannot wake up the CPU if they are disabled. Hence, the CPU would be stuck in idle mode until the watchdog resets the device. The only solution would be to re-enable interrupts just before halting the CPU and disabling interrupts once the CPU woke up. Here is the pseudo-code of what would os_tick_idle look like: void os_tick_idle(uint32_t ticks) { OS_ASSERT_CRITICAL(); setup_timer(ticks); OS_EXIT_CRITICAL(); asm volatile ("wait"); // Halt CPU (idle mode) OS_ENTER_CRITICAL(); stop timer advance_time setup_timer(1) // timer is setup to generate interrupt for every tick } Do you think that would be acceptable ? Let me know if you have suggestions how to handle this case. Best Regards, François
