Am 27.04.19 um 16:40 schrieb Christian Mauderer:
> Am 24.04.19 um 10:00 schrieb Jython:
>> HI, ALL!
>> why the code stuck in wakeup handler while the RTC gets time work fine
>> i have checked some days, but no register error found, i suspect that
>> the handler function is the issue
>>
>>
>> // code
>> rtems_isr rtc_wakeup_handler(rtems_vector_number vector)
>> {
>>
>> uint32_t STM32F4_RTC_ISR = (*(volatile uint32_t *)(0x4000280C));
>>
>> // clear 10bit
>> if(STM32F4_RTC_ISR & (1<<10))
>> {
>> //printk("wak\n");
>> STM32F4_RTC_ISR &= ~(1<<10);
>> STM32F4_RTC_ISR &= 0xfffffbff;
>> }
>>
>> volatile uint32_t EXIT_PR = *(volatile uint32_t*)0x40013C14;
>> printk("before clr %08x\n", EXIT_PR);
>> EXIT_PR |= 1<<22;
>>
>> int i;
>> for(i = 0; i < 1000; i++) i = i + 1 - 1;
>> printk(" %08x\n", EXIT_PR);
>> }
>>
>>
>> the printed log attached, why the EXIT_PR bit22 not cleared
>>
>>
>
> Hello Jython,
>
> your EXIT_PR seems to be slightly odd. What you do:
>
> volatile uint32_t EXIT_PR = *(volatile uint32_t*)0x40013C14;
>
> This means you read the content of 0x40013C14 and write it to a 32 bit
> value.
>
> Later you do
>
> EXIT_PR |= 1<<22;
>
> This changes the _copy_ of the value.
>
> What you most likely want to do is the following:
>
> volatile uint32_t *EXIT_PR = (volatile uint32_t*)0x40013C14;
> *EXIT_PR |= 1<<22;
>
> This would change the value at 0x40013C14 and not only your copy.
>
> By the way: You tried to do a busy wait. That's not a good idea in an
> interrupt. The way you implemented it, the compiler most likely even
> just removes it:
>
> int i;
> for(i = 0; i < 1000; i++) i = i + 1 - 1;
>
> The compiler most likely notices that this statement has no effect. If
> you would like to implement a busy wait that way, you should use a
> volatile int.
>
> Note that RTEMS has a rtems_counter_delay_nanoseconds() function. That
> is a busy wait loop. It is based on the CPU counter and provides a
> method for short busy waits for example during driver initialization.
> But again: Please don't use busy waits in Interrupts. It's not a good
> idea and will lead to problems sooner or later.
>
> Best regards
>
> Christian Mauderer
Oh, and I just noted: You are writing a one to the register but expect
the bit to be cleared. So it is most likely a "write one to clear"
register (which is quite common for interrupt flags). In that case you
maybe don't want to use a
*EXIT_PR |= 1<<22;
but a
*EXIT_PR = 1<<22;
Otherwise you clear other flags in that register too. Please have a look
at the reference manual of your chip to decide that.
Best regards
Christian
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