Newhaven Products > Character LCDs

NHD-0 420D 3Z- FL-GBW Backlight brightness won't change .

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samuelproulx:
Hello

In the light of a recent project, I was trying to adjust the backlight brightness of a NHD-0420D3Z-FL-GBW display through coding , but even with the commands specified in the datasheet, I am unable to change the brightness.  Here is the section that adjusts it in my code :

delay_ms(200);
putc(0xFE);
putc(0x53);
putc(0x08);

. . .

Anyone have any idea's as to why it won't change? I am stumped. I did manage to make it change before, and when that happened I was not able to change it back again.

Thanks

Saurabh_B:
Hi,

That does seem like the proper method to change the backlight, do you have any commands you call before that that would cause the command to not work.

Also what interface are you using with the display, and at what speed?

engsvcsgrp:
I too am having the same problem with a similar display (NHD-0420D3Z-NSW-BBW-V3).  Of the 8 displays I ordered, I can only change the black light on 3 of them.  On another 3, I can only change the backlight if the display powers up with the backlight already on.  I set the back light intensity every 500ms as part of a housekeeping loop.  Is there a way to hardwire the back light on continuously?  7 of the 8 will light the backlight in self test mode.  I am using I2C at 50khz.  All other commands seem to work fine. 

samuelproulx:
Hello,

Alright I know it is a little late to reply, as this is over a year ago, I totally forgot about the post.

But I did manage to figure out the problem.

After issuing a command to change the contrast, I believe the problem was that it requires that you leave a certain delay AFTER issuing the command and not before, to give it time to do the change and all.

IF I remember correctly...

Paul_B:
Glad to hear you got your display up and running!

Thanks for sharing your solution, it will definitely help others  :D

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