HT56R67 datasheet(65/104 Pages) HOLTEK

65 / 104 page

HT56R67/HT56R668/HT56C668/HT56R678/HT56C678/HT56R688

Rev. 1.20

March 4, 2010

PA0/PA1 Pin Function Control

PAC Register

PAC0

PAC Register

PAC1

PA Data Register

PA0

PA Data Register

PA1

Output

Function

001

PA0=BZ

PA1=BZ

000

PA0=

²0²

PA1=

²0²

011

PA0=BZ

PA1=input line

010

PA0=

²0²

PA1=input line

PA0=input line

PA1=D

PA0=input line

²x

² stands for don¢t care

²D² stands for Data ²0² or ²1²

If configuration options have selected that only the PA0

pin is to function as a BZ buzzer pin, then the PA1 pin

can be used as a normal I/O pin. For the PA0 pin to func-

tion as a BZ buzzer pin, PA0 must be setup as an output

by setting bit PAC0 of the PAC port control register to

zero. The PA0 data bit in the PA data register must also

be set high to enable the buzzer output, if set low pin

PA0 will remain low. In this way the PA0 bit can be used

as an on/off control for the BZ buzzer pin PA0. If the

PAC0 bit of the PAC port control register is set high, then

pin PA0 can still be used as an input even though the

configuration option has configured it as a BZ buzzer

output.

Note that no matter what configuration option is chosen

for the buzzer, if the port control register has setup the

pin to function as an input, then this will override the con-

figuration option selection and force the pin to always

behave as an input pin. This arrangement enables the

pin to be used as both a buzzer pin and as an input pin,

so regardless of the configuration option chosen; the ac-

tual function of the pin can be changed dynamically by

the application program by programming the appropri-

ate port control register bit.

I n t e r n a l C l o c k S o u r c e

P A 0 D a t a

B Z O u t p u t a t P A 0

B Z O u t p u t a t P A 1

P A 1 D a t a

Buzzer Output Pin Control

Note:

The above drawing shows the situation where both pins PA0 and PA1 are selected by configuration option to

be BZ and BZ buzzer pin outputs. The Port Control Register of both pins must have already been setup as out-

put. The data setup on pin PA1 has no effect on the buzzer outputs.

HT56R67 Datasheet(PDF) 65 Page - Holtek Semiconductor Inc

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