HT86A72 datasheet(27/68 Pages) HOLTEK

27 / 68 page

HT86Axx/HT86ARxx

Rev. 1.10

December 12, 2012

Port A has the additional capability of providing wake-up

functions. When the device is in the Power Down Mode,

various methods are available to wake the device up.

One of these is a high to low transition of any of the Port

A pins. Single or multiple pins on Port A can be setup to

have this function.

Timers

The provision of timers form an important part of any

microcontroller, giving the designer a means of carrying

out time related functions. The devices in the Voice Type

MCU series contain four count up timers of 8-bit capac-

ity. Each timer has only one operating mode, which is to

act as a general timer. The provision of an internal

prescaler to the clock circuitry of the timers gives added

range to the timer.

Configuring the Timer Input Clock Source

The clock source of Timer0/Timer1/Tmier2 is the system

clock divided by four and the clock source of Timer3 is

the system clock divided by four or the RTC clock which

is derived from a external 32kHz crystal. A configuration

option determines which clock is selected. If the RTC

clock is selected then note that it will continue to run

when the device is powered down using the HALT in-

struction. The 8-bit timer clock source is also first di-

vided by a prescaler, the division ratio of which is

conditioned by the three lower bits of the associated

timer control register.

Timer Registers

- TMR0, TMR1, TMR2, TMR3

The timer registers are special function registers located

in the special purpose Data Memory and is the place

where the actual timer value is stored. The value in the

timer registers increases by one each time an internal

clock pulse is received. The timer will count from the ini-

tial value loaded by the preload register to the full count

of FFH at which point the timer overflows and an internal

interrupt signal is generated. The timer value will then

be reset with the initial preload register value and con-

tinue counting.

T i m e r M o d e C o n t r o l

T 0 O N

T 1 O N

T 2 O N

P r e l o a d R e g i s t e r

T i m e r

D a t a B u s

R e l o a d

O v e r f l o w

t o I n t e r r u p t

T 2 P S C 2 ~ T 2 P S C 0

T 1 P S C 2 ~ T 1 P S C 0

T 0 P S C 2 ~ T 0 P S C 0

8 - B i t T i m e r

f S Y S / 4

P r e s c a l e r

( 1 / 2 ~ 1 / 2 5 6 )

T 2 T M 1

T 1 T M 1

T 0 T M 1

T 2 T M 0

T 1 T M 0

T 0 T M 0

8-bit Timer Structure

- TMR0, TMR1, TMR2

V D D

R e a d D a t a R e g i s t e r

C K

C o n t r o l B i t

P u l l - H i g h

O p t i o n

D a t a B u s

W r i t e C o n t r o l R e g i s t e r

C h i p R e s e t

R e a d C o n t r o l R e g i s t e r

W r i t e D a t a R e g i s t e r

D a t a B i t

P D 0 D a t a B i t

S C S , S C K , S D I , S D O

S e r i a l I n t e r f a c e

W e a k

P u l l - u p

P D 0 ~ P D 7

S C S , S C K , S D I , S D O

PD Input/Output Port

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