CFAG12864U3-TFH Brightness Issue

Akilarasan R

New member
Hi there ,

I'm using CFAG12864U3-TFH LCD display. Whenever i'm trying to fill the LCD screen with characters, brightness level is getting darker and characters not visible as it used to be. Please, refer below attached images and help me resolve this.
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Akilarasan R

New member
Actually I'm suspecting hardware setup but i just want to know any brightness configuration that we are forgetting to implement. Is there any brightness configuration for this part?

CF Kelsey

Staff member
Contrast is set in the software. The icons in the top row are also changing between your two images. These icons are also set in the code. It gets worse as you send more information to the display. It appears you're sending some commands to the display along with your text which is why I asked for your code.

You can see a list of commands for this display in the controller datasheet here:

Our demonstration code for this display is available here:

A sample schematic is available in the datasheet for the breakout board for this display here (page 6):

Akilarasan R

New member
Hi ,

I have doubt regarding LED of CFAG12864U3-TFH. In datasheet, maximum and minimum voltage requirement for back light is not mentioned.

Please tell me the maximum voltage that I can supply to LED.