HTG1390 Просмотр технического описания (PDF) - Holtek Semiconductor

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HTG1390

4-bit Microcontroller

Holtek Semiconductor 

Preliminary

HTG1390

LCD driver output

All LCD segments are random after an initial

clear. The bias voltage circuits of the LCD dis-

play is built-in and no external resistor is

needed.

The output number of the HTG1390 LCD driver

is 27×3 which can directly drive an LCD with

1/3 duty cycle and 1/2 bias.

The frequency of the LCD driving clock is fixed

at about 128Hz. This is set by Holtek according

to the application and cannot be changed.

Interfacing

The HTG1390 microcontroller communicate

with the outside world through 4-bit input port

PS, 3-bit input port PP and one 4-bit output port

PA.

Input ports – PP, PS

All ports can have internal pull high resistors

determined by mask option. Every bit of the

input ports PP and PS can be specified to be a

trigger source to wake up the HALT interrupt

by mask option . A high to low transition on one

of these pins will wake up the device from a

HALT status.

LCD driver output

Note: VLCD is produced by double voltage

circuit, therefore its value is double by

VDD.

Oscillator

Only one external resistor is needed for the

HTG1390 oscillator circuit.

The system clock is also used as the reference

signal of the LCD driving clock, sound effect

clock and internal frequency source of TIMER.

One HTG1390 machine cycle consists of a se-

quence of 4 states numbered T1 to T4. Each

state lasts for one oscillator period. The ma-

chine cycle is 16µs if the system frequency is up

to 256kHz.

Input ports PP and PS

Output port – PA

A mask option is available to select whether the

output is a CMOS or open drain NMOS type.

After an initial clear the output port PA defaults

to be high for CMOS or floating for NMOS.

RC oscillator

Output port PA

11

17th Nov ’98

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