HT46801N-1 Holtek Semiconductor, HT46801N-1 Datasheet - Page 30

• Manufacturer Part Number: HT46801N-1
• Description: (HT4xR01x-1) Small Package 8-Bit OTP MCU
• Manufacturer: Holtek Semiconductor

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I/O Port Control Registers
Each Port has its own control register, known as PAC,
PBC, which controls the input/output configuration. With
this control register, each I/O pin with or without
pull-high resistors can be reconfigured dynamically un-
der software control. For the I/O pin to function as an in-
put, the corresponding bit of the control register must be
written as a 1 . This will then allow the logic state of the
input pin to be directly read by instructions. When the
corresponding bit of the control register is written as a
is currently setup as an output, instructions can still be
used to read the output register. However, it should be
noted that the program will in fact only read the status of
the output data latch and not the actual logic status of
the output pin.
Pin-shared Functions
The flexibility of the microcontroller range is greatly en-
hanced by the use of pins that have more than one func-
tion. Limited numbers of pins can force serious design
constraints on designers but by supplying pins with
multi-functions, many of these difficulties can be over-
come. For some pins, the chosen function of the
multi-function I/O pins is set by configuration options
while for others the function is set by application pro-
gram control.
Rev.1.00
0 , the I/O pin will be setup as a CMOS output. If the pin
External Interrupt Input
The external interrupt pin, INT, is pin-shared with an
I/O pin. To use the pin as an external interrupt input
the correct bits in the INTC0 register must be pro-
grammed. The pin must also be setup as an input by
setting the PAC3 bit in the Port Control Register. A
pull-high resistor can also be selected via the appro-
priate port pull-high resistor register. Note that even if
the pin is setup as an external interrupt input the I/O
function still remains.
External Timer/Event Counter Input
The Timer/Event Counter pins, TC0 and TC1 are
pin-shared with I/O pins. For these shared pins to be
used as Timer/Event Counter inputs, the Timer/Event
Counter must be configured to be in the Event Coun-
ter or Pulse Width Capture Mode. This is achieved by
setting the appropriate bits in the Timer/Event Counter
Control Register. The pins must also be setup as in-
puts by setting the appropriate bit in the Port Control
Register. Pull-high resistor options can also be se-
lected using the port pull-high resistor registers. Note
that even if the pin is setup as an external timer input
the I/O function still remains.
30
PFD Output
The PFD function output is pin-shared with an I/O pin.
The output function of this pin is chosen using the
CTRL0 register. Note that the corresponding bit of the
port control register, must setup the pin as an output
to enable the PFD output. If the port control register
has setup the pin as an input, then the pin will function
as a normal logic input with the usual pull-high selec-
tion, even if the PFD function has been selected.
PWM Outputs
For the HT46R01B-1 and HT46R01N-1 devices the
PWM function is included. The PWM function whose
outputs are pin-shared with I/O pins. The PWM output
functions are chosen using the CTRL0 register. Note
that the corresponding bit of the port control registers,
for the output pin, must setup the pin as an output to
enable the PWM output. If the pins are setup as in-
puts, then the pin will function as a normal logic input
with the usual pull-high selections, even if the PWM
registers have enabled the PWM function.
A/D Inputs
The HT46R01B-1 and HT46R01N-1 devices have
four inputs to the A/D converter. All of these analog in-
puts are pin-shared with I/O pins. If these pins are to
be used as A/D inputs and not as I/O pins, then the
corresponding PCRn bits in the A/D converter control
register, PCR or ANCSR, must be properly setup.
There are no configuration options associated with
the A/D converter. If chosen as I/O pins, then full
pull-high resistor control remains, however if used as
A/D inputs then any pull-high resistor control associ-
ated with these pins will be automatically discon-
nected.
HT46R01B-1/HT46R01N-1
HT48R01B-1/HT48R01N-1
June 9, 2011
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