Fujitsu MB89202, F202RA manual Port, Input Output

CHAPTER 4 I/O PORTS

4.4Port 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 4.4-1lists the pins of port 4.

Table 4.4-1		Pins of Port 4
Port		Pin		Peripherals for	Input and output form		Circuit
			Function	which the pin
name		name			Input	Output	type
				may serve
	P40/AN0		P40 I/O	AN0 analog input 0
						CMOS push-
	P41/AN1		P41 I/O	AN1 analog input 1	CMOS
Port 4						pull/N-ch open-	F
	P42/AN2		P42 I/O	AN2 analog input 2	analog
						drain
	P43/AN3		P43 I/O	AN3 analog input 3

For circuit type, see Section "1.7 Pin Functions Description " and "1.8 I/O Circuit Types ".

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