HT45R34 datasheet(13/41 Pages) HOLTEK

13 / 41 page

HT45R34

Rev. 1.20

October 15, 2007

Timer/Event Counter

An 8-bit timer/event counter, known as Timer/Event

Counter, is implemented in the microcontroller. The

Timer/Event Counter contains an 8-bit programmable

count-up counter whose clock may come from an exter-

nal source or from the system clock. Using the external

clock input allows the user to count external events, mea-

sure time internals or pulse widths, or generate an accu-

rate time base. Using the internal clock allows the user to

generate an accurate time base.

There are 2 registers related to the Timer/Event Coun-

ter, TMR and TMRC. Two physical registers are mapped

to the TMR location; writing to TMR places the start

value of the Timer/Event Counter in a preload register

while reading TMR retrieves the contents of the

Timer/Event Counter. The TMRC is a timer/event coun-

ter control register, which defines the timer operating

conditions.

Reset

(Power-on)

WDT Time-out

(Normal Operation)

RES Reset

(Normal Operation)

RES Reset

(HALT)

WDT Time-out

(HALT)*

TMRC

00-0 1000

uu-u uuuu

1111 1111

uuuu uuuu

PAC

1111 1111

uuuu uuuu

ASCR

---1 1111

---u uuuu

INTC1

---0 ---0

---u ---u

TMRAH

xxxx xxxx

uuuu uuuu

TMRAL

xxxx xxxx

uuuu uuuu

RCOCCR

0000 1---

uuuu u---

TMRBH

xxxx xxxx

uuuu uuuu

TMRBL

xxxx xxxx

uuuu uuuu

RCOCR

1xxx --00

uuuu --uu

Note:

²*² means ²warm reset²

²u² means ²unchanged²

²x² means ²unknown²

Bit No.

Label

Function

0~2

TPSC0~TPSC2

To define the prescaler stages, TPSC2, TPSC1, TPSC0=

000: fINT=fSYS

001: fINT=fSYS/2

010: fINT=fSYS/4

011: fINT=fSYS/8

100: fINT=fSYS/16

101: fINT=fSYS/32

110: fINT=fSYS/64

111: fINT=fSYS/128

3TE

To define the TMR active edge of the timer/event counter

(0=active on low to high; 1=active on high to low)

TON

To enable or disable timer counting (0=disabled; 1=enabled)

Unused bit, read as

²0²

TM0

TM1

To define the operating mode, TM1, TM0=

01=Event count mode (external clock)

10=Timer mode (internal clock)

11=Pulse width measurement mode

00=Unused

TMRC (0EH) Register

HT45R34 数据表(PDF) 13 Page - Holtek Semiconductor Inc

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