HT49RA0 Ver la hoja de datos (PDF) - Holtek Semiconductor

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HT49RA0

Remote Type 8-Bit MCU with LCD

Holtek Semiconductor 

HT49RA0/HT49CA0

It is recommended that a program not use the ²CALL

subroutine² within the interrupt subroutine. It¢s because

interrupts often occur in an unpredictable manner or re-

quire to be serviced immediately in some applications.

At this time, if only one stack is left, and enabling the in-

terrupt is not well controlled, operation of the ²call² in the

interrupt subroutine may damage the original control se-

quence.

Oscillator Configuration

An external resistor between OSC1 and VSS in needed

and the resistance is about 12kW. The RC oscillator

provides a ±3% accuracy, the conditions are:

· VDD=2.0V~3.6V

· Temp.= 0°C ~ 50°C

· fSYS=4MHz

O SC1

R C O s c illa to r

System Oscillator

LCD/RTC OSC Control Register

Two bit in (1FH) are for controlling LCD and RTC OSC.

Bit No.

0

1

Label

RTCEN

LCDEN

Function

Controls RTC OSC enable (1=enabled; 0=disabled)

Controls LCD enable (1=enabled; 0=disabled)

2~7

¾

Unused bit, read as ²0²

LCDC (1FH) Register

LCDEN and RTCEN may decide LCD and RTC On/Off condition on normal operation.

fS Clock

Source

fSYS/4

WDT OSC

RTC OSC

(WDT enable)

RTC OSC

(WDT disable)

LCD/WDT Control Bits

LCDEN, RTCEN=0, 0 LCDEN, RTCEN=0, 1 LCDEN, RTCEN=1, 0 LCDEN, RTCEN=1, 1

LCD off, RTC off

LCD off, RTC off

LCD on, RTC off

LCD on, RTC off

LCD off, RTC off

LCD off, RTC off

LCD on, RTC off

LCD on, RTC off

LCD off, RTC on

LCD off, RTC on

LCD on, RTC on

LCD on, RTC on

LCD off, RTC off

LCD off, RTC on

LCD on, RTC on

LCD on, RTC on

Rev. 1.20

10

October 24, 2007

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