MC68HC705BD3 FREESCALE [Freescale Semiconductor, Inc], MC68HC705BD3 Datasheet - Page 23

• Manufacturer Part Number: MC68HC705BD3
• Description: High-density complementary metal oxide semiconductor (HCMOS) microcontroller unit
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

2.3
In the User Mode there are 24 bidirectional I/O lines arranged as 4 I/O ports (Port A, B, C, and D).
The individual bits in these ports are programmable as either inputs or outputs under software
control by the data direction registers (DDRs). Also, if enabled by software, Port C and D will have
additional functions as PWM outputs, M-Bus I/O and Sync Signal Processor outputs.
2.3.1
Port A is an 8-bit bidirectional port which does not share any of its pins with other subsystems.
The Port A data register is at $00 and the data direction register (DDR) is at $04. Reset does not
affect the data register, yet clears the data direction register, thereby returning the ports to inputs.
Writing a one to a DDR bit sets the corresponding port bit to output mode.
2.3.2
Port B is a 6-bit bidirectional port which does not share any of its pins with other subsystems. PB2
to PB5 are +10V open-drain port pins. The Port B data register is at $01 and the data direction
register (DDR) is at $05. Reset does not affect the data register, yet clears the data direction
register, thereby returning the ports to inputs. Writing a one to a DDR bit sets the corresponding
port bit to output mode.
MC68HC05BD3
INPUT/OUTPUT PORTS
Port A
Port B
Figure 2-2 Pin Assignment for 42-pin SDIP Package
PIN DESCRIPTION AND I/O PORTS
IRQ/ VPP
RESET
EXTAL
PWM2
PWM1
PWM0
XTAL
VDD
VSS
PB5
PB4
PB3
PB2
PB1
PB0
PA7
PA6
PA5
PA4
PA3
NC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
VSYNC
HSYNC
PWM3
PWM4
PWM5
NC
PWM6
PWM7
PC7/PWM15/HTTL
PC6/PWM14/VTTL
PC5/PWM13
PC4/PWM12
PC3/PWM11
PC2/PWM10
PC1/PWM9
PC0/PWM8
PD1/SCL
PD0/SDA
PA0
PA1
PA2
TPG
2-3
2