Re: [avr-chat] when is loop_until_bit_is_set/clear required after setting a bit?

[Ormund Williams]

On Wed, 2016-09-07 at 14:19 -0800, Britton Kerin wrote:
> I remember reading somewhere in avr libc docs to do e.g. this:
> 
>     PCIFR = _BV (some_bit)
>     loop_until_bit_is_clear (PCIFR, some_bit);
> 
> This may be a bad example becuase of the odd write-one-to-clear
> semantics.  That isn't the point here, I don't remember which
> registers this advice applied to.  And I can't find it now.
> 
> 
> The only thing I could find in the datasheet that related to this was
> in section 13.2.4 of ATMega328P datasheet, where it says that you
> have to wait a cycle after assigning an output pin value before
> reading it back in.
> 
> Are there other cases where loop_until_* or a nop is required?
> 
The only thing I can think of is writing to the EEPROM.  You can also
use that function to block waiting for a flag to be set by a timer,
interrupt or other peripheral.

__
Ormund