TOPWAY

LCD Module User Manual

LM3121

www.topwaysz.com

Document Name: LM3121-Manual-Rev0.2

Page: 7 of 9

4. Function Specifications

4.1

Basic Setting

To drive the LCD module correctly and provide normally display, please use the following setting

Select duty = 1/32

Static drive ON/OFF = OFF (Normal Driving)

ADC = 0

Display Start Line = 0

DISPLAY ON/OFF = ON

Read-Modify-Write = OFF

4.2

Resetting the LCD module

The LCD module should be initialized by the hardware reset during power on sequence.

Keep /RES terminal at high level, during the power on.

After the power supply is stable, a hardware reset signal should apply to the /RES terminal.

The LCD module will be initialized at the rising and falling edge of the RES signal.

For normal running, /RES signal must be keep at high level

After the Hardware Reset, the LCD module controllers status will be:

(note: this is not the basic setting for normal display)

-

Display ON/OFF = OFF

-

Display start line register = 0

-

Static drive ON/OFF = OFF (Normal Driving)

-

Column address counter = 0

-

Page address register = Page 3

-

Select duty = 1/32

-

ADC = 1

-

Read-Modify-Write = OFF

Caution:

Never keep /RES signal at Low level for more than 1ms, otherwise unexpected high current drawn will occur due to

the internal data collision. It may permanently damage the LCD module.

4.3

Adjusting the LCD Display Contrast

A Variable-Resistor must be connected to the LCD

module for providing a reference to V0. Adjusting the VR

will result the change of LCD display contrast.

The recommended value of VR is 25k to 50k

LCD module

VDD

V0

VOUT