HT47C10L datasheet(13/38 Pages) HOLTEK

13 / 38 page

HT47C10L

Rev. 1.90

November 30, 2005

Timer/Event Counter

One 16-bit timer/event counter or RC type A/D converter

is implemented in the HT47C10L. The ADC/TM bit (bit 1

of ADCR register) decides whether timer A and timer B

are composed of one 16-bit timer/event counter or timer

A and timer B are composed of RC type A/D converter.

The TMRAL, TMRAH, TMRBL, TMRBH composed of

one 16-bit timer/event counter, when ADC/TM bit is

²0².

The TMRBL and TMRBH are timer/event counter

preload registers for lower-order byte and higher-order

byte respectively.

The timer/event counter clock source comes from system

clock (fSYS) or external source (A/D clock from pad:RCIN).

The external clock input allows the user to count external

events, count external RC type A/D clock, measure time in-

tervals or pulse widths, or generate an accurate time base.

There are six registers related to the timer/event counter

operating mode. TMRAH ([20H]), TMRAL ([21H]), TMRC

([22H]), TMRBH ([23H]), TMRBL ([24H]) and ADCR

([25H]). Writing to TMRBL only writes the data into a low

byte buffer, and writing to TMRBH will write the data and

the contents of the low byte buffer into the time/event coun-

ter preload register (16-bit) simultaneously. The

timer/event counter preload register is changed by writ-

ing to TMRBH operations and writing to TMRBL will keep

the timer/event counter preload register unchanged.

Reading TMRAH will also latch the TMRAL into the low

byte buffer to avoid the false timing problem. Reading

TMRAL returns the contents of the low byte buffer. In

other words, the low byte of the timer/event counter can

not be read directly. It must read the TMRAH first to

make the low byte contents of timer/event counter be

latched into the buffer.

The TMRC is the timer/event counter control register,

which defines the timer/event counter options. The

timer/event counter control register define the operating

mode, counting enable or disable and active edge. Writ-

ing to timer B location puts the starting value in the

timer/event counter preload register, while reading timer

A yields the contents of the timer/event counter. Timer B

is timer/event counter preload register.

The TM0 and TM1 bits define the operation mode. The

event count mode is used to count external events,

which means that the clock source (A/D clock) comes

from an external (RCIN) pin. The timer mode functions

as a normal timer with the clock source coming from the

internal clock source (fSYS). Finally, the pulse width

measurement mode can be used to count the high or

low level duration of the external signal (A/D clock from

pad:RCIN). The counting is based on the system clock

(fSYS).

In the event count, A/D clock or internal timer mode,

once the timer/event counter starts counting, it will count

from the current contents in the timer/event counter

(TMRAH and TMRAL) to FFFFH. Once overflow occurs,

the counter is reloaded from the timer/event counter

preload register (TMRBH and TMRBL) and generates

the corresponding interrupt request flag (TF; bit 4 of

INTC) at the same time.

In the pulse width measurement mode with the TON

and TE bits equal to one, once the RCIN has received a

transient from low to high (or high to low if the TE bit is

0) it will start counting until the A/D Clock returns to the

original level and resets the TON. The measured result

will remain in the timer/event counter even if the acti-

vated transient occurs again. In other words, only one

cycle measurement can be done. Until setting the TON,

T E

S y s t e m C l o c k ( f S Y S )

T M 1

T M 0

T 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

T i m e r / e v e n t c o u n t e r

( 1 6 b i t T i m e r A )

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

( 1 6 b i t T i m e r B )

D a t a B u s

R e l o a d

O v e r f l o w

T M 1

T M 0

R C I N

A D C / T M = 0

A D E N

M O D E

T O N

T M 0

A D C / T M

A D E N

R t o F c o n v e r t e r

( A D C R B i t - 2 ) M o d e

R R E F

R S E N

C o n t r o l

2 2 0 0 p F

3 0 k W

2 0 k W ~ 6 0 k W

A / D C l o c k

Timer/Event Counter

HT47C10L Datasheet(PDF) 13 Page - Holtek Semiconductor Inc

HT47C10L Datasheet(HTML) 13 Page - Holtek Semiconductor Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Datasheet Download

Link URL