Hello there,
I'm relatively new to STM32- and RL-ARM-Programming. I'm using Keil, the STM32F107VC-controller, the standard peripheral library and the RTX-Kernel.
I am developing a device, which will work user driven: Only when the user pushs a button, the system has to work a short time. Beside that, every 10 to 20 seconds some device states (e.g.: battery status) have to be checked.
So the device will mostly wait for user input in the os_idle_demon()-task. To save power, I want to put the controller into sleep-mode. Therefore, I'm calling __WFI() in the endless loop of the os_idle_demon()-task.
My problem is, that __WFI() returns immediately and doesn't wait for any interrupt. I assume, that some OS-timer generate interrupts, so that __WFI() returns immediately. Does anybody has an idea, how I can put the device to sleep reliably? I can't use a stop mode, because I also want to be able to use timer-interrupts.
I wrote a similar code, where I called __WFI() from the main loop (without RTX-support) and it worked fine. So the structure of my code doesn't seem to have failures.
Greetings, Hardy
Now I've found a soulution for my problem:
I've enclosed the __WFI()-command between the calls of "tsk_lock()" and "tsk_unlock()".
tsk_lock(); //Disable RTX System Tick Timer interrupts __WFI(); tsk_unlock(); //Enable RTX System Tick Timer Interrupts.
According to the documentation, these calls disable/enable the system tick timer interrupts. So, during the call of __WFI(), no task switch is possible. But external interrupts or internal (timer-)interrupts still work and wake up the controller.
Do you think, this is a good solution?