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Forum Index : Microcontroller and PC projects : MM+ TFT Backlight PWM issue

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WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2948

Posted: 03:59am 29 Aug 2016

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Trying to get a smooth effect to turn off the TFT Backlight on an MM+.

Trying a sub as follows:

FOR x = 100 TO 0 STEP -1
BACKLIGHT x
PAUSE 2
NEXT x

50% of the time I get what I need - i.e. a smooth 'switching off' of the TFT

HOWEVER, the other 50% off the time, I get a 'bright flicker' as if the BACKLIGHT value is set to 100 instead of x.

I have tried different PAUSE delays to see if it could be a timing issue (i.e. data sent to SSD chip too quickly) but no difference.

Any ideas as to what the issue may be; or indeed how best to achieve this?

Note: I am using the 'reverse technique to smoothly turn on the display and this works absolutely fine 100% of the time!

Thanks,

WW

WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2948

Posted: 04:18am 29 Aug 2016

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SOLVED

I just happened to be using a TFT that was still set to use LED_A as opposed to SSD_PWM. I always use SSD_PWM but had't yet modified this TFT

With SSD_PWM control - it is much better (as mentioned in Geoff's excellent manual!)

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