HTG2190 datasheet(24/50 Pages) HOLTEK

24 / 50 page

HTG2190

Rev. 1.20

July 5, 2002

rives as VIH (input high voltage) of S1 gate, the NMOS

will be turned on for discharge. The same manner can

be used for measuring the related frequency of R2, but

the roles of PB2 and PB3 should be exchanged.

During execution of R to F function, the TMR1 should be

set as event counter to count the charge/discharge

waveform. Since the falling edge of the charge/dis-

charge waveform is sharper than the rising edge, it is

recommended that the active edge of the event counter

on high to low be defined by setting TE (bit 3 of TMR1C).

For other detailed operation about Timer/Event Counter

1, refer to a related section of the Timer/Event Counter

0/1.

An example of a software program written for the pur-

pose of measuring related frequency of R2 is shown be-

low.

SET

PBC.3

;

set PB.3 to be input pin

CLR

PBC.2

;

set PB.2 to be output pin

SET

PB.2

;

output source current at

PB.2

CLR

¢TALC.3

;

disable TMR1 pull-high

resistor

Mov

A, 48H

;

set TMR1 to be event

counter

Mov

TMR1C, A

;

and active edge on high to

low

CLR

TMR1L

;

set TMR1L and TMR1H to

²00²

CLR

TMR1H

;

SET

TMR1C.4

;

turn on TMR1

SET

¢ALC.1

;

turn on R to F function

Timer 2/3

Timer 2 is an 8-bit counter, and its clock source come

from the system clock divided by an 8-stage prescaler.

There are two registers related to timer 2 ; TMR2 (21H)

and TMR2C (22H). Two physical registers are mapped

to TMR2 location; writing to TMR2 makes the starting

value be placed in the Timer 2 preload register and

reading the TMR2 obtains the contents of the timer 2

counter. The TMR2C is a control register, which defines

the division ratio of the prescaler and counting enable or

disable.

Writing data to B2, B1 and B0 (bit 2, 1, 0 of TMR2C) can

generate various clock source.

Once the timer 2 starts counting, it will count from the

current contents in the counter to FFH. Once an over-

flow occurs, the counter is reloaded from the preload

bit 4 of the INTCH). To enable the counting operation,

the timer on bit (TON ; bit 4 of TMR2C) should be set to

²1².

For proper operation, bit 6 of TMR2C should be set to

²1², and bit3, bit7 should be set to ²0².

Timer 2 can also be used as a buzzer output by setting

PB.0 and AUD to be PWM1 and PWM2 output respec-

tively by mask option. When the PWM1/PWM2 is se-

lected, setting 2FH.6/2FH.7 to

²1² will select PFD/PFDB

output and setting 2FH.6/2FH.7 to

²0² will select

PWM1/PWM2 output. When the PFD/PFDB function is

selected, setting 2FH.4/2FH.5 to

²1² will enable

PFD/PFDB output and setting 2FH.4/2FH.5 to

²0² will

disable PFD/PFDB output. PFD Frequency= T2f/

[(256-TMR2)

´2].

TMR2C

T2f

SYS CLK/2

SYS CLK/4

SYS CLK/8

SYS CLK/16

SYS CLK/32

SYS CLK/64

SYS CLK/128

SYS CLK/256

TMR2C Bit4 to enable/disable timer counting (0=dis-

able;1=enable)

TMR2C Bit3, always write

²0²

TMR2C Bit5, always write

²0²

TMR2C Bit6, always write

²1²

TMR2C Bit7, always write

²0²

V I H

V I L

Charge/discharge waveform

HTG2190 Datasheet(PDF) 24 Page - Holtek Semiconductor Inc

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