HT46C232 datasheet(15/50 Pages) HOLTEK

15 / 50 page

HT46R232/HT46C232

Rev. 1.40

November 23, 2005

To enable the counting operation, the Timer ON bit

(T0ON: bit 4 of TMR0C; T10N: bit 4 of TMR1C) should

be set to 1. In the pulse width measurement mode, the

T0ON/T1ON is automatically cleared after the measure-

ment cycle is completed. But in the other two modes, the

T0ON/T1ON can only be reset by instructions. The

overflow of the Timer/Event Counter 0/1 is one of the

wake-up sources and can also be applied to a PFD (Pro-

grammable Frequency Divider) output at PA3 by op-

tions. Only one PFD (PFD0 or PFD1) can be applied to

PA3 by options. If PA3 is set as PFD output, there are

two types of selections; One is PFD0 as the PFD output,

the other is PFD1 as the PFD output. PFD0, PFD1 are

the timer overflow signals of the Timer/Event Counter 0,

Timer/Event Counter 1 respectively. No matter what the

operation mode is, writinga0to ET0I or ET1I disables

the related interrupt service. When the PFD function is

selected, executing

²SET [PA].3² instruction to enable

PFD output and executing

²CLR [PA].3² instruction to

disable PFD output.

In the case of timer/event counter OFF condition, writing

data to the timer/event counter preload register also re-

loads that data to the timer/event counter. But if the

timer/event counter is turn on, data written to the

timer/event counter is kept only in the timer/event coun-

ter preload register. The timer/event counter still contin-

ues its operation until an overflow occurs.

When the timer/event counter (reading TMR0/TMR1) is

read, the clock is blocked to avoid errors, as this may re-

sults in a counting error. Blocking of the clock should be

taken into account by the programmer. It is strongly rec-

ommended to load a desired value into the TMR0/TMR1

counter, for proper operation since the initial value of

TMR0/TMR1 is unknown. Due to the timer/event

scheme, the programmer should pay special attention

on the instruction to enable then disable the timer for the

first time, whenever there is a need to use the

timer/event function, to avoid unpredictable result. After

this procedure, the timer/event function can be operated

normally.

T 0 M 1

T 0 M 0

T M R 0

T 0 E

T 0 M 1

T 0 M 0

T 0 O N

P u l s e W i d t h

M e a s u r e m e n t

M o d e C o n t r o l

8 - s t a g e P r e s c a l e r

8 - 1 M U X

f S Y S

f I N T

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

( 6 + 2 ) o r ( 7 + 1 )

C o m p a r e

P W M

T o P D 0 / P D 1 / P D 2 / P D 3 C i r c u i t

1 6 - B i t

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

L o w B y t e

B u f f e r

H i g h B y t e

L o w B y t e

1 6 - B i t T i m e r / E v e n t C o u n t e r

P F D 0

Timer/Event Counter 0

T 1 M 1

T 1 M 0

T M R 1

T 1 E

T 1 M 1

T 1 M 0

T 1 O N

P u l s e W i d t h

M e a s u r e m e n t

M o d e C o n t r o l

f S Y S / 4

f I N T

1 6 - B i t

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

L o w B y t e

B u f f e r

H i g h B y t e

L o w B y t e

1 6 - B i t T i m e r / E v e n t C o u n t e r

P F D 1

Timer/Event Counter 1

1 / 2

P F D

P F D S o u r c e O p t i o n

P A 3 D a t a C T R L

P F D 0

P F D 1

PFD Source Option

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