Ensure LCD Display Optimum Contrast in Mass Production

LCD screen optimum contrast

Keeping product quality consistent is a major topic for manufacturer, so is making sure LCD uniform display effect.

In mass production situation, each finish product's LCD driving voltage may have tolerance. LCD driver IC's internal reference voltage may contain small deviation, too. These add up, could make the final product LCD display contrast vary.

Topway LM240160D & LM240160G series LCM make use of Sitronix ST7529 on-chip EEPROM, to store a contrast adjustment value for better display.

It is recommended to call out that value during LCM start-up routine, as below:

//--------------- Call out EEPROM compensation ---------------

SdCmd(0x30); // select ext0 command set

SdCmd(0x07); SdData(0x19); // run ACK signal

SdCmd(0x31); // select ext1 command set

SdCmd(0xcd); SdData(0x00); delayms(100); // enable EEPROM function

SdCmd(0xfd); delayms(100); // call out the EEPROM value

SdCmd(0xcc); // finish EEPROM function

For start-up program routine, please refer to LM240160G sample code.

For ST7529 commands, please see ST7529 datasheet.