Is LCD fading via code possible?

[pichutch]

Hi, well the question's in the title really. I'd like to fade a sentence onto the AXE033 screen and wondered if it was possible.

Cheers.... Ben

 

[Andrew Cowan]

I can only think of replacing the contrast pot with a digital pot...

In other words, not be software with the axe033. However, scrolling is possible.

On backlit LCDs, you can slowly turn the backlight on/off to simulate fading.

Andrew

 

[hippy]

In theory you could repeatedly rewrite the display switching between spaces and the text, a sort of PWM, but the PICAXE/AXE033 probably isn't quick enough for that, but it could be worth a try via I2C

 

[Andrew Cowan]

Expanding on Hippy's idea - you could switch between clear the screen and display preset message as quickly as you can. See what happens when you do this:

init: pause 500
main: serout 7,N2400,(253,1,”Fading LCD test.”)
pause 1000
serout,7,N2400,(254,1)
pause 30
serout,7,N2400,(235,1)
goto fade

Fade:
serout,7,N2400,(254,8)     ;hide display
pause 1
serout,7,N2400,(254,12)   ;restore display
pause 1
goto fade

Try changing the two 'pause 1' times to reduce flicker.

Let us know how it goes.

Also, change the serout 7 to whatever pin you are using.

Andrew

 

[Dippy]

Does that work?
I just tried it at PIC speeds and its annoying.

 

[demonicpicaxeguy]

Does that work?
I just tried it at PIC speeds and its annoying.

a better way would be to vary the supply voltage ,i'm sure somthing could be done with pwm a transistor and a capicitor

 

[Technical]

You could remove one letter at a time, may have a similar effect.

 

[hippy]

LCD's are usually very sensitive to opertating voltages so I'd expect that to be a fruitless effort.

 

[Dippy]

I don't mean to sound a killjoy, but with a standard LCD I think the whole gentle-fading plan is potentially fruitless.
Maybe the MOSFET resistance for adjusting contrast eh?