HT95R22 datasheet(18/52 Pages) HOLTEK

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HT95R22

Rev. 1.00

January 6, 2009

T M R 0 C R e g i s t e r

N o t i m p l e m e n t e d , r e a d a s " 0 "

b 7

E v e n t C o u n t e r A c t i v e E d g e S e l e c t

1 : c o u n t o n f a l l i n g e d g e

0 : c o u n t o n r i s i n g e d g e

T 0 E

T 0 O N

T 0 M 0

T 0 M 1

b 0

T i m e r / E v e n t C o u n t e r C o u n t i n g E n a b l e

1 : e n a b l e

0 : d i s a b l e

O p e r a t i n g M o d e S e l e c t

T 0 M 1

T 0 M 0

n o m o d e a v a i l a b l e

e v e n t c o u n t e r m o d e

t i m e r m o d e

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

P u l s e W i d t h M e a s u r e m e n t A c t i v e E d g e S e l e c t

1 : s t a r t c o u n t i n g o n r i s i n g e d g e , s t o p o n f a l l i n g e d g e

0 : s t a r t c o u n t i n g o n f a l l i n g e d g e , s t o p o n r i s i n g e d g e

N o t i m p l e m e n t e d , r e a d a s " 0 "

Timer/Event Counter 0 Control Register

T M R 1 C R e g i s t e r

N o t i m p l e m e n t e d , r e a d a s " 0 "

b 7

T 1 O N

T 1 M 0

T 1 M 1

b 0

T i m e r / E v e n t C o u n t e r C o u n t i n g E n a b l e

1 : e n a b l e

0 : d i s a b l e

O p e r a t i n g M o d e S e l e c t

N o t i m p l e m e n t e d , r e a d a s " 0 "

T 1 M 1

T 1 M 0

n o t u s e d

t i m e r m o d e

n o t u s e d

Timer/Event Counter 1 Control Register

riod will remain in the preload register and will only be

written into the timer register the next time an overflow

occurs.

Reading from and writing to these registers is carried

out in a specific way. It must be noted that when using in-

structions to preload data into the low byte register,

namely TMR0L or TMR1L, the data will only be placed in

a low byte buffer and not directly into the low byte regis-

ter. The actual transfer of the data into the low byte reg-

ister is only carried out when a write to its associated

high byte register, namely TMR0H or TMR1H, is exe-

cuted. Also, using instructions to preload data into the

high byte timer register will result in the data being di-

rectly written to the high byte register. At the same time

the data in the low byte buffer will be transferred into its

associated low byte register. For this reason, when

preloading data into the 16-bit timer registers, the low

byte should be written first. It must also be noted that to

read the contents of the low byte register, a read to the

high byte register must first be executed to latch the con-

tents of the low byte buffer from its associated low byte

can be read in the normal way. Note that reading the low

byte timer register directly will only result in reading the

previously latched contents of the low byte buffer and

not the actual contents of the low byte timer register.

Timer Control Registers

- TMR0C, TMR1C

The flexible features of the Holtek microcontroller

Timer/Event Counters enable various control options to

be made available for each of the Timer/Event Coun-

ters. These options are determined by the contents of its

control register, which has the name TMR0C/TMR1C. It

is the Timer Control Register together with its corre-

sponding timer register pair that control the full opera-

tion of each Timer/Event Counter. Before the

Timer/Event Counter can be used, it is essential that the

Timer Control Register is fully programmed with the

right data to ensure its correct operation, a process that

is normally carried out during program initialisation.

To choose which of the three modes the Timer/Event

Counter 0 is to operate in, either in the timer mode, the

event counting mode or the pulse width measurement

mode, bits 7 and 6 of the Timer Control Register, which

are known as the bit pair T0M1/T0M0, must be set to the

required logic levels. Note that the Timer/Event Counter

1 only have the timer mode. The Timer/Event Counter

HT95R22 Datasheet(PDF) 18 Page - Holtek Semiconductor Inc

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