invert colors on CF 634 display


New member
How does one invert the colors on the display of a 634 LCD display? Essentially what I want to do is set every pixel on the screen to black. The purpose is to ensure there are no dead pixels in the display. I've been looking through your datasheet on this unit but can't seem to find what I'm looking for. We're currently interfacing with the unit by sending raw commands to the COM port, and it's working well.
We're using the display to output some measurements generating by a dimensioning machine we created. Because it's a device that falls under "Weights and measures", it's performance and feature set must be inspected and certified by the government. This "dead pixel test" is part of what they require to meet their standards.

Can anyone help with this?

Thanks in advance,
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CF Support2


The command you are looking for is the contrast control. By maxing out the contrast, you will be turning on all the pixels. The contrast command is on page 43 of the datasheet.

Basically, send a command 15 (0x0F / Ctrl+O) followed by a "100". That will set all your pixels to dark regardless of the text currently on the display. You can then send another command 15 to set the contrast back to normal. We set the CFA634 to "65" when the units are programmed and tested prior to shipment.