Questions:

Application

Do I have to check the busy flag of my display controller?

In my application after a power on the LCD voltage is present long before the logic supply voltage of my display. Can this cause any trouble?

My application used to work OK with the HD44780 controller on my display, but with the new controller replacement I run into trouble. What is the reason for that?

What means DVI ?



Answers:

Do I have to check the busy flag of my display controller?
No, you don´t have to. If you don´t do so, the waiting time between instructions should be longer than the execution instructon time. 50us are recommended. Refer to the specification of your controller.

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In my application after a power on the LCD voltage is present long before the logic supply voltage of my display. Can this cause any trouble?
Yes, the controller provides a AC signal (M-signal) to the LCD that prevents the LCD to accumulate DC voltage which can reduce the lifetime of your LCD. The controller may also run into troubble if the logic supply voltage rises to slowly. In worst case the internal drivers of the display hook into a socalled latch-up effect and the display is damaged totally. Refer also to our application notes.

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My application used to work OK with the HD44780 controller on my display, but with the new controller replacement I run into trouble. What is the reason for that?
Check your bus timing. The HD44780 used to be much more tolerant agaist timing violations than the new controllers are. (SPLC780, KS-0066, ST-7066....) Somtimes it can be helpful to set the enable after the data are valid and to reset it again before the data get invalid.

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What means DVI ?
DVI is the short cut for Digital Visual Interface and stands for an international standard supported by VESA and DDWG. This standard describes a fully digital interface for TFT displays and monitors to a PC. There is no costly conversion of analogue RGB ro digital TFT necessary.

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