MC9S08RC8 Datasheet, PDF (74/234 Pages) Freescale Semiconductor, Inc – Microcontrollers

Parallel Input/Output
6.3 Pin Descriptions
The MC9S08RC/RD/RE/RG has a total of 39 parallel I/O pins distributed between four 8-bit ports and one
7-bit port. Not all pins are bonded out in all packages. Consult the pin assignment in Chapter 2, “Pins and
Connections,” for available parallel I/O pins. All of these pins are available for general-purpose I/O when
they are not used by other on-chip peripheral systems.
The following paragraphs discuss each port and the software controls that determine each pin’s use.
6.3.1 Port A
Port A
Bit 7
MCU Pin:
PTA7/
KBI1P7
6
5
4
3
PTA6/ PTA5/ PTA4/ PTA3/
KBI1P6 KBI1P5 KBI1P4 KBI1P3
Figure 6-1. Port A Pin Names
2
PTA2/
KBI1P2
1
PTA1/
KBI1P1
Bit 0
PTA0/
KBI1P0
Port A is an 8-bit general-purpose I/O port shared with the KBI1 keyboard interrupt inputs. Bit 0 of port
A is an input-only pin.
Port A pins are available as general-purpose I/O pins controlled by the port A data (PTAD), data direction
(PTADD), and pullup enable (PTAPE) registers. Refer to Section 6.4, “Parallel I/O Controls,” for more
information about general-purpose I/O control.
Any of the port A pins can be configured as a KBI1 keyboard interrupt pin. Refer to the Keyboard Interrupt
(KBI) Module chapter for more information about using port A pins as keyboard interrupt pins.
6.3.2 Port B
Port B
Bit 7
MCU Pin:
PTB7/
TPM1CH1
6
5
4
3
PTB6 PTB5 PTB4 PTB3
Figure 6-2. Port B Pin Names
2
PTB2
1
PTB1/
RxD1
Bit 0
PTB0/
TxD1
Port B is an 8-bit general-purpose I/O port with two pins shared with the SCI and one pin shared with the
TPM. The port B output drivers are capable of high current drive.
Port B pins are available as general-purpose I/O pins controlled by the port B data (PTBD), data direction
(PTBDD), and pullup enable (PTBPE) registers. Refer to Section 6.4, “Parallel I/O Controls,” for more
information about general-purpose I/O control.
When the SCI module is enabled, PTB0 and PTB1 function as the transmit (TxD1) and receive (RxD1)
pins of the SCI. Refer to the Serial Communications Interface (SCI) Module chapter for more information
about using PTB0 and PTB1 as SCI pins.
The TPM can be configured to use PTB7 as either an input capture, output compare, or PWM pin. Refer
to the Timer/PWM Module (TPM) Module chapter for more information about using PTB7 as a timer pin.
MC9S08RC/RD/RE/RG Data Sheet, Rev. 1.11
74
Freescale Semiconductor