HT46C64 datasheet(17/47 Pages) HOLTEK

17 / 47 page

HT46R64/HT46C64

Rev. 1.40

September 21, 2004

Timer/Event Counter

Two timer/event counters (TMR0,TMR1) are imple-

mented in the microcontroller. The Timer/Event Counter

0 contains a 8-bit programmable count-up counter and

the clock may come from an external source or an inter-

nal clock source. An internal clock source comes from

fSYS. The Timer/Event Counter 1 contains a 16-bit pro-

grammable count-up counter and the clock may come

from an external source or an internal clock source. An

internal clock source comes from fSYS/4 or 32768Hz se-

lected by option. The external clock input allows the

user to count external events, measure time intervals or

pulse widths, or to generate an accurate time base.

There are two registers related to the Timer/Event

Counter 0; TMR0 ([0DH]) and TMR0C ([0EH]). Two

physical registers are mapped to TMR0 location; writing

TMR0 puts the starting value in the Timer/Event Coun-

ter 0 register and reading TMR0 takes the contents of

the Timer/Event Counter 0. The TMR0C is a timer/event

counter control register, which defines some options.

There are three registers related to the Timer/Event

Counter 1; TMR1H (0FH), TMR1L (10H) and TMR1C

(11H). Writing TMR1L will only put the written data to an

internal lower-order byte buffer (8-bit) and writing

TMR1H will transfer the specified data and the contents

of the lower-order byte buffer to TMR1H and TMR1L

registers, respectively.

The Timer/Event Counter 1 preload register is changed

everytime there is a writing operation to TRM1H. Read-

ing TMR1H will latch the contents of TMR1H and

TMR1L counters to the destination and the lower-order

byte buffer, respectively. Reading the TMR1L will read

the contents of the lower-order byte buffer. The TMR1C

is the Timer/Event Counter 1 control register, which de-

fines the operating mode, counting enable or disable

and an active edge.

The T0M0, T0M1 (TMR0C) and T1M0, T1M1 (TMR1C)

bits define the operation mode. The event count mode is

used to count external events, which means that the

clock source is from an external (TMR0, TMR1) pin. The

timer mode functions as a normal timer with the clock

source coming from the internal selected clock source.

Finally, the pulse width measurement mode can be used

to count the high or low level duration of the external sig-

nal (TMR0, TMR1), and the counting is based on the in-

ternal selected clock source.

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

P F D 0

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 - b i t T i m e r / E v e n t C o u n t e r

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

8 - b i t T i m e r / E v e n t C o u n t e r

( T M R 0 )

D a t a B u s

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

Timer/Event Counter 0

P F D 1

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 I N T

f S Y S / 4

3 2 7 6 8 H z

T 1 S

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

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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