saunj:
3. It is a HD44780 character display, so great speed is not needed - there are only 40 characters and the user must read it.
It kind of depends on what is being done in the rest of the code and how it is being done.
There is the refresh rate and then there is the latency.
The refresh rate is the rate at which the LCD is updated or changed.
The latency is the amount of time it takes to get the information to the display
once the display needs to be updated.
In a shift register implementation like these 100% of the latency is processing
time that is robbed from the CPU.
So even though the refresh may not need to very high say as low as a few times a second,
there may be some critical realtime needs that do not allow a particular amount of latency
when updating the LCD.
Normally for such instances, the overall code would use interrupts to yank the CPU away from something like
the LCD library into the more critical code.
But in some cases the code may not be using interrupts, in that case,
as long as the LCD code is fast enough to meet the minimum latency,
all the code could be done in the foreground without having to use interrupts.
---- bill