CFA635 doesn't respond to set-contrast with value 0xFF

[Hfuy]

I have here a CFA-635 TMF KS (h1.0,s1.3) which appears not to respond to a request to set its LCD contrast to 0xFF. The exact packet I am sending is:

0x0D,0x01,0xFF,0x13,0x2F

Now, I know that setting the contrast to 0xFF is a fairly crazy thing to do, but it is documented as being the full single byte range. Values below 255 work fine. Either my CRC code is off, which wasn't my first thought as it works fine with other long ASCII strings of text, or this is some sort of glitch on the display.

Any thoughts?

P

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[CF Tech]

. . . I know that setting the contrast to 0xFF is a fairly crazy thing to do . . .

Yes

. . . Any thoughts?

It is a documentation error.

The valid range for command 13 should be 0-254, not 0-255.

I'll ask the document folks to put a note in the current data sheet, or fix it with a revision.

Other notes: Setting the contrast to 254 will do whatever it was you wanted to accomplish with setting it to 255

 

[Hfuy]

Thanks for that.

I'm afraid I just happened to punch in 0xFF while testing some code