HT46R01 datasheet(18/60 Pages) HOLTEK

18 / 60 page

HT46R01/HT46R02/HT46R03

Rev. 1.00

September 21, 2007

means that all I/O pins will default to an input state, the

level of which depends on the other connected circuitry

and whether pull-high options have been selected. If the

PAC port control register, is then programmed to setup

some pins as outputs, these output pins will have an ini-

tial high output value unless the associated PA port data

puts and which are outputs can be achieved byte-wide

by loading the correct value into the port control register

or by programming individual bits in the port control reg-

ister using the

²SET [m].i² and ²CLR [m].i² instructions.

Note that when using these bit control instructions, a

read-modify-write operation takes place. The

microcontroller must first read in the data on the entire

port, modify it to the required new bit values and then re-

write this data back to the output ports.

Pins PA0 to PA6 each have a wake-up functions, se-

lected via the PAWK register. When the device is in the

Power Down Mode, various methods are available to

wake the device up. One of these is a high to low transi-

tion of any of the these pins. Single or multiple pins on

Port A can be setup to have this function.

Timer/Event Counters

The provision of timers form an important part of any

microcontroller, giving the designer a means of carrying

out time related functions. The devices contain either

one or two count-up timers each of 8-bit capacity de-

pending upon which device is selected. As each timer

has three different operating modes, they can be config-

ured to operate as a general timer, an external event

counter or as a pulse width measurement device. The

provision of an internal prescaler to the clock circuitry of

some of the timer/event counters gives added range to

the timer.

There are two types of registers related to the

Timer/Event Counters. The first is the register that con-

tains the actual value of the timer and into which an ini-

tial value can be preloaded. Reading from this register

retrieves the contents of the Timer/Event Counter. The

second type of associated register is the Timer Control

mines how the timer is to be used. All devices can have

the timer clock configured to come from the internal

clock source. In addition, the timer clock source can also

be configured to come from an external timer pin. The

accompanying table lists the associated timer register

names.

HT46R01

HT46R02

HT46R03

No. of 8-bit Timers

Timer Register Name

TMR0

TMR1

Timer Control Register

TMR0

TMR0C

TMR1C

An external clock source is used when the timer is in the

event counting mode, the clock source being provided

on the external timer pin, known as TMR0 or TMR1 de-

pending on which device is selected. These external

timer pins are pin-shared with other I/O pins. Depending

upon the condition of the T0E or T1E bit in the corre-

sponding Timer Control Register, each high to low, or

low to high transition on the external timer input pin will

increment the counter by one.

Configuring the Timer/Event Counter Input Clock

Source

The internal timer

¢s clock can originate from various

sources, depending upon which device and which timer

is chosen. The system clock input timer source is used

when the timer is in the timer mode or in the pulse width

measurement mode. For Timer/Event Counter 0 this

system clock timer source is first divided by a prescaler,

the division ratio of which is conditioned by the Timer

Control Register bits T0PSC0~T0PSC2.

An external clock source is used when the timer is in the

event counting mode, the clock source being provided

on an external timer pin TMR0 or TMR1, depending

upon which device and which timer is used. Depending

upon the condition of the T0E or T1E bit, each high to

low, or low to high transition on the external timer pin will

increment the counter by one.

T 1

T 2

T 3

T 4

T 1

T 2

T 3

T 4

W r i t e t o P o r t

R e a d f r o m P o r t

S y s t e m C l o c k

P o r t D a t a

Read/Write Timing

T M R 0

T 0 E

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

M o d e C o n t r o l

T 0 O N

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

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

P F D

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

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

( 1 / 2 ~ 1 / 2 5 6 )

T 0 M 1

T 0 M 0

f S Y S

R T C O s c i l l a t o r

T 0 S

8-bit Timer/Event Counter 0 Structure

- All Devices

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