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CHAPTER 5 I/O PORTS
5.3
Block Diagram of I/O Ports (Including the Pull-up Resistor)
This section provides a block diagram of an I/O port with a pull-up resistor.
I Block diagram of I/O port with a pull-up resistor
Figure 5.3-1 "Block diagram of a port including the pull-up resistor" shows a block diagram of an
I/O port with a pull-up resistor.
Figure 5.3-1 Block diagram of a port including the pull-up resistor
Data Bus
PDR read
Notes:
•
Pull-up resistor control register (PCR): Specifies whether to turn the pull-up resistor on or off.
0: Pull-up resistor is OFF
1: Pull-up resistor is ON
•
In stop mode, the setting of the pull-up control register is prioritized.
•
When the pin is used as an external bus pin, the pull-up resistor control function cannot be
used. Do not write 1 to this register.
152
Resource output
Resource output
enabled
Resource input
Pull-up resistor (approximately 50 K
PDR : Port Data Register
DDR : Data Direction Register
PCR : Pull-up Control Register
)
pin
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