HT67F60 datasheet(220/242 Pages) HOLTEK

220 / 242 page

Rev. 1.50

220

March 06 , 2012

Rev. 1.50

221

March 06 , 2012

HT67F30/HT67F40/HT67F50/HT67F60

TinyPowerTM A/D Flash Type 8-Bit MCU with LCD & EEPRO

Programming Considerations

Certain precautions must be taken when programming the LCD. One of these is to ensure that the

LCD Memory is properly initialised after the microcontroller is powered on. Like the General

Purpose Data Memory, the contents of the LCD Memory are in an unknown condition after power-

on. As the contents of the LCD Memory will be mapped into the actual display, it is important to

initialise this memory area into a known condition soon after applying power to obtain a proper

display pattern.

Consideration must also be given to the capacitive load of the actual LCD used in the application.

As the load presented to the microcontroller by LCD pixels can be generally modeled as mainly

capacitive in nature, it is important that this is not excessive, a point that is particularly true in the

case of the COM lines which may be connected to many LCD pixels. The accompanying diagram

depicts the equivalent circuit of the LCD.

One additional consideration that must be taken into account is what happens when the

microcontroller enters the Idle or Slow Mode. The LCDEN control bit in the LCDCTRL register

permits the display to be powered off to reduce power consumption. If this bit is zero, the driving

signals to the display will cease, producing a blank display pattern but reducing any power

consumption associated with the LCD.

After Power-on, note that as the LCDEN bit will be cleared to zero, the display function will be

disabled.

CO M0

CO M1

CO M2

CO Mn

SE G0

SE G1

SE G2

SE Gn

LCD Panel Equivalent Circuit

HT67F60 Datasheet(PDF) 220 Page - Holtek Semiconductor Inc