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Re: [avr-gcc-list] How to (efficeiently !!!) test a bitwithinamulti-byte

From: Vincent Trouilliez
Subject: Re: [avr-gcc-list] How to (efficeiently !!!) test a bitwithinamulti-byte intege
Date: Sat, 05 Nov 2005 20:05:43 +0100

> Didn't I tell you to poll the LCD's busy bit in the first place?  
> Wouldn't have had the above problem if you had.  :-)
> --
> David Kelly N4HHE, address@hidden

Yes yes, you did ;-)
So I decided to tackle it last night, and I wired the LCD R/W line.
I now poll the Busy Flag successfully, but I am a bit confused about how
it really works. The data sheet of the LCD module doesn't give much
detail about this particular point. All it says is to read a byte, and
that the BF is bit 7. But I use the 4 bit interface and somehow, I
couldn't get it to work. I now wonder if it's possible to read the LCD
in 4-bit mode at all ?! The data sheet is completely mute about this
point, they don't even give timing diagrams for the 4 bit mode, so I had
to improvise.
In despair, I tried to simply read bit 7 without pulsing the 'Enable'
line at all, and well, it happened to work. But had it not worked, I
would have been completely in the dark and would have had to give up on
polling, because of the lack of reference information in the datasheet !
What's that for a datasheet...pfff....


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