Re: LCD display Busy Flag
- From: cbarn24050@xxxxxxx
- Date: 31 Dec 2006 03:56:29 -0800
Arlet wrote:
cbarn24050@xxxxxxx wrote:
Sagaert Johan wrote:
Hi
Can i check the busy flag of the display while continously keeping the
Enable high or should i pulse the enable ?
Johan
You need to strobe the enable. Someone else has mentioned that you dont
need to use it if you use a timer, this is fine for small displays (up
to 16 chars for a 2mS timer) or if you can accept a short delay in
updating. If you need a fast update on a larger display, say if you
were editing text or monitoring real time data, you need to reduce the
timer to 50uS and use the busy flag with a character buffer.
Strobing the enable isn't such a big deal anyway, if you intend to busy
wait. No need to optimize a delay loop :)
I agree that a timer based solution is best suited to smaller displays,
although with a suitably fast processor, bigger sized displays can be
handled fine. Right now, I'm working with a 4x20 character display.
Using a 2kHz timer interrupt, I get 25 screen updates/second, which is
plenty for the slow LCD. Interrupt overhead is about 2
usecs/character,resulting in 0.4% CPU utilization.
Why would you want to busy wait? If busy just exit, try again on next
timer interrupt. You should use the busy flag at 2kHz since some
intructions take 1.6mS. 25 screen updates is fine I have found that 10
per second is fine as well, its just noticable when editing or
scrolling through a menu.
.
- References:
- LCD display Busy Flag
- From: Sagaert Johan
- Re: LCD display Busy Flag
- From: cbarn24050
- Re: LCD display Busy Flag
- From: Arlet
- LCD display Busy Flag
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