Question about "Slow HD44780" option


New member
Hi all,

Just got my CFAH2004A-TMI-JP wired up and working. I love this thing!

Anyway, I'm using the excellent CrystalControl software, and have noticed a little problem. When ever the screen updates sometimes an entire line of text will shift over to the left one character. On the right a random character will appear. Sometimes, if I switch the screen, then switch it back, the text is properly aligned.

I noticed that if I check the "Slow HD44780" option, the problem goes away.

What makes my display a slow hd44780? Is there a problem with my hookup that's making it respond slowly? Thanks for the info.

Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.

CF Mark

Slow HD44780 just increases the timing used between sending signals to the parallel LCDs.

Having a long cable to the LCD could cause you to need this option, as could odd timings within CrystalControl or Windows.

Not much you can do about it.


New member
Thanks for the info. That makes sense, seeing as how I have a 3' parallel cable.

It's nice that you thought to include that option, since my display wouldn't be working correctly without it.