HT46R0664 datasheet(45/92 Pages) HOLTEK

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Rev. 1.00

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Rev. 1.00

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HT46R0664

Enhanced A/D+LCD 8-Bit OTP MCU

Timer/Event Counter

The provision of timers form an important part of any microcontroller, giving the designer a means

of carrying out time related functions. The device contains two count-up timer of 8-bit capacity. As

the timers have three different operating modes, they can be configured to operate as a general timer,

an external event counter or as a pulse width capture device. The provision of an internal prescaler

to the clock circuitry on giving added range to the timers.

There are two types of registers related to the Timer/Event Counters. The first is the register that

contains the actual value of the timer and into which an initial value can be preloaded. Reading

from this register it retrieves the contents of the Timer/Event Counter. The second type of associated

is to be used. The device 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.

Configuring the Timer/Event Counter Input Clock Source

The Timer/Event Counter clock source can originate from various sources, an internal clock or an

external pin. The internal clock source is used when the timer is in the timer mode or in the pulse

width capture mode, this internal clock source is firstly divided by a prescaler, the division ratio of

which is conditioned by the Timer Control Register bits T0PS2~T0PS0. For Timer/Event Counter 0,

the internal clock source can be fSYS, PFD0 or the LXT Oscillator, the choice of which is determined

by the T0S[1:0] bit in the CTRL1 register. For Timer/Event Counter 1, the clock source can be fSYS/4

or the LXT Oscillator, the choice of which is determined by the T1S bit in the TMR1C register.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 TCn. Depending upon the condition of the TnEG bit, each high to

low, or low to high transition on the external timer pin will increment the counter by one.

LCD Clock Prescaler

Time Base 0

Time Base 1

B�zzer

MUX

LIRC

fSYS/4

LXT

Confi�. OPT

fs clock so�rce

LCD Driver

Time Base 0 interr�pt period

Time Base 1 interr�pt period

B�zzer

MU X

f TP

f SYS

f LX T

PW MC 1

PW MC 0

T0 S0

T0 PS [2 :0 ]

7 St age Co un te r

To T im er 0 i nt er na l cl oc k

8- 1 MU X

PF D0

T0 S1

Clock Structure

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