HT46R74D-1 Holtek Semiconductor, HT46R74D-1 Datasheet - Page 15

• Manufacturer Part Number: HT46R74D-1
• Description: Dual Slope A/D Type MCU
• Manufacturer: Holtek Semiconductor

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If the 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
function as a BZ buzzer pin, PA0 must be setup as an
output by setting bit PAC0 of the PAC port control regis-
ter 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
Note:
Rev. 1.10
PAC Register
X stands for don t care
PAC.0
0
0
0
0
1
1
PAC Register
PAC.1
0
0
1
1
0
1
PA0/PA1 Pin Function Control
Buzzer Output Pin Control
PA data Register
PA.0
0
1
0
1
0
X
15
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.
Note:The above drawing shows the situation where
both pins PA0 and PA1 are selected by a configuration
option to be BZ and BZ buzzer pin outputs. The Port
Control Register of both pins must have already been
setup as outputs. The data setup on pin PA1 has no ef-
fect on the buzzer outputs.
PA data Register
PA.1
X
X
X
X
X
X
PA0=0, PA1=0
PA0=BZ, PA1=BZ
PA0=0, PA1=Input
PA0=BZ, PA1=Input
PA0=Input, PA1=0
PA0=Input, PA1=Input
Output Function
HT46R74D-1
January 11, 2007