HTG12N0 datasheet(13/30 Pages) HOLTEK

13 / 30 page

LCD driver output

All of the LCD segments are random after an

initial clear. The bias voltage circuits of the

LCD display is built-in and no external resistor

is required.

The output number of the HTG12N0 LCD

driver is 64

×8 which can directly drive an LCD

with 1/8 duty cycle and 1/5 bias.

The LCD driving clock frequency is fixed at

256Hz. This is set by the RTC OSC (32.768kHz).

LCD driver output can be enabled or disabled

by setting PC1 without the influence of the

related memory condition.

LCD driver output is enabled by setting PC1 as

“1”, and disabled by setting PC1 as “0”.

An example of an LCD driving waveform (1/8

duty and 1/5 bias) is shown below.

Oscillator

Only one external resistor is required for the

HTG12N0 system clock.

The system clock is also used as the reference

signal of the sound effect clock or internal fre-

quency source of TIMER.

Another crystal oscillator is needed for use as

the reference signal of LCD driving clock and

RTC interrupt clock source.

A machine cycle consists of a sequence of four

states numbered T1 to T4. Each state lasts for

one oscillator period. The machine cycle is 4

µs

if the system frequency is up to 1MHz.

LCD display memory

RC and RTC oscillator

HTG12N0

18th Mar ’99

HTG12N0 Datasheet(PDF) 13 Page - Holtek Semiconductor Inc