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CHAPTER 4 I/O PORTS
4.4 Port 4
Port 4 is a type of I/O port that is switched between CMOS push-pull and N-ch open-
drain and may also serve analog inputs. Each pin of this port can be used for
peripherals or normal port function that can be selected according to the setting of the
bit corresponding to the pin on a specific register.
This section explains the I/O port function of CMOS push-pull/ N-ch open-drain type.
This section also describes port 4 concerning to the structure, pins, a block diagram of
pins, and associated registers.
■ Structure of Port 4
Port 4 comprises the following four elements:
• Type of I/O pins that are switched between CMOS push-pull and N-ch open-drain and analog input pins
(P40/AN0 to P43/AN3)
• Port 4 data register (PDR4)
• Port 4 data direction register (DDR4)
• Port 4 output format setting register (OUT4)
■
Pins of Port 4
Port 4 has four I/O pins of CMOS push-pull/N-ch open-drain.
These pins can also be used as analog input pins.
Those pins that are used for analog inputs cannot be used as a general-purpose I/O port. Table 4.4-1 lists
the pins of port 4.
For circuit type, see Section "1.7 Pin Functions Description " and "1.8 I/O Circuit Types ".
Table 4.4-1 Pins of Port 4
Port
name
Pin
name
Function
Peripherals for
which the pin
may serve
Input and output form
Circuit
type
Input Output
Port 4
P40/AN0 P40 I/O AN0 analog input 0
CMOS
analog
CMOS push-
pull/N-ch open-
drain
F
P41/AN1 P41 I/O AN1 analog input 1
P42/AN2 P42 I/O AN2 analog input 2
P43/AN3 P43 I/O AN3 analog input 3