ST7789 datasheet(154/316 Pages) SITRONIX

154 / 316 page

ST7789VI

Version 1.4

Page 154 of 315

2014/04

Sitronix Confidential

The information contained herein is the exclusive property of Sitronix and shall not be distributed, reproduced, or

disclosed in whole or in part without prior written permission of Sitronix.

8.22.2 Minimum brightness setting of CABC function

CABC function is automatically reduced backlight brightness based on image contents. In the case of the

combination with the LABC or manual brightness setting, display brightness is too dark. It must affect to

image quality degradation. CABC minimum brightness setting is to avoid too much brightness reduction.

When CABC is active, CABC can not reduce the display brightness to less than CABC minimum brightness

setting. If CABC algorithm works without any abnormal visual effect, image processing function can operate

even when the brightness can not be changed.

This function does not affect to the other function, manual brightness setting. Manual brightness can be

set the display brightness to less than CABC minimum brightness. Smooth transition and dimming function

can be worked as normal.

When display brightness is turned off (BCTRL=0 of “9.1.39 Write CTRL Display (53h)”), CABC minimum

brightness setting is ignored. “9.1.44 Read CABC minimum brightness (5Fh)” always read the setting value of

“9.1.43 Write CABC minimum brightness (5Eh)”.

WRCABC (55h)

Function

RDCABCMB (5Fh)

Image

Sleep-in

WRCABCMB (5Eh)

CABC off

00b

Disable

WRCABCMB (5Eh)

Original

CABC on

01b/10b/11b

Enable

WRCABCMB (5Eh)

CABC modified

Brightness level calculates with the following formula.

Display Output Brightness = Manual brightness setting * CABC brightness ratio

Below drawing is for the explanation of the CABC minimum brightness setting.

ST7789 Datasheet(PDF) 154 Page - Sitronix Technology Co., Ltd.