Peripheral Circuits; Display - Huawei U8860 Maintenance Manual

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U8860

Maintenance Manual

9.4 Peripheral Circuits

The MSM8255 employs the MDDI interface to transmit command and data to the LCD. The

U8860 uses Toshiba's LCD. The U8860 uses Toshiba's LCD LT040MDT9000. It is a TFT

module with a point matrix of 480RGB x 854, supporting MDDI interface. Its features are:



The schematic diagram of the MSM8255 and LCD interface is as follows:

The U8860's LCD employs the MDDI-type2 interface. It requires only two pairs of low

voltage differential signal (LVDS) cables and a pair of power cables, and supports 60 Hz

refreshment rate. With frame synchronization function, the LCD uses MDP_VSYNC of

GPIO_030 as the data transmission synchronization signal to avoid LCD breakage.

A diode composes the PWM signal (pull-up) reflected by environment light detection and the

PWM signal reflected by LCD's dynamic backlight adjustment function to a signal and

performs computation to control the backlight brightness.

The signal definitions are as follow:

Signal

VREG_L16_2P8

VREG_L12_1P8

MDDI_SP

MDDI_SN

Issue 1.0 (2011-11-14)

16.7 M colors, TFT-LCD module

Display mode: RGB Stripe

Huawei Proprietary and Confidential

Description

LCD analog voltage, 2.8 V

I/O connector digit voltage, 1.8 V

LVDS + signal

LVDS - signal

9 Principles and Troubleshooting

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