Clearing a LCD-area as soon as possible

[CS]

Hi all,

I have build a schematic for a VU-Meter with a PIC and a LCD. It works great but it is a little bit slow. May be someone is able to help me.

Here is the code to build the bargraph:

Code: Select all

......
Dim ADVUL as byte
Dim ADVUR as byte

....

Sub ADInAsVURect(value,sline,eline As Byte)
 Dim x As Integer

 For x = 1 To value
     Rectangle (3*x+14,sline,3*x+15,eline)    
 Next

End Sub


Repeat

ADVUL = (ADC.Read(2)+1)/32 
ADVUR = (ADC.Read(3)+1)/32

ADInAsVURect(ADVUL,17,20)
ADInAsVURect(ADVUL,24,27)

Until False

The code reads the values from the ADC channel 2 and 3 and divide it with 32. The maximal bars are 32 (1024/32 = 32).
Until here it works great! But before I have to show new bars, I have to clear the area, and here is my problem. When I use for example Pen.Color = 0 and a For - Next to clear the area then the VU-Meter is very slow and doesn't look nice.

Can anybody give me a hint, how to clear the area as soon as possible?

Thanks in advance

Christian

[johngb]

Why not clear or draw just the difference between last sample and this sample. If its going up you only have to draw the increase, if its going down you only have to clear the decrease.

[Doj]

Can you up the speed of the micro, does it have a pll?
If you use the pll it will refresh 4 times as quickly.

[Steven]

Which GLCD are you using?

[CS]

Hi all,

@ johngb: Yes, thats what I'm thinking of, but I don't have the right idea.

@ Doj: I use the PIC 18F4620. This MCU have a PLL. At this time I use him with 20MHz. When I use the PLL I can have 40MHz.

@ Steven: I use my favorite display type EA-DIP with the SED 1520 Controller.

Christian

[Jon Chandler]

An easy way to clear the screen or invert the screen is to create a screen-size graphic and use the setimage command. If the screen has static information (like a title and boxes for example), creating a graphic with everything on it may be faster than redrawing the screen each time it's cleared.

Jon

[CS]

Hallo all again,

I'm back with no success.

@ Jon Candler: The command 'setimage' was so slow, that it wasn't useful.

Now I'm trying to convert johngb's tip!?

Christian

[CS]

Hi all,

thanks for the hints. Now I have solved the problem.

The best solution is the hint from johngb! Thanks again for that!

Reguards

Christian