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Parallel Input/Output
MC9S08RC/RD/RE/RG Data Sheet, Rev. 1.11
74
Freescale Semiconductor
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 andConnections,” 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
Figure 6-1. Port A Pin Names
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
information about general-purpose I/O control.
Any of the port A pins can be congured 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
Figure 6-2. Port B Pin Names
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
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 congured 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.
Port A
Bit 7
654321
Bit 0
MCU Pin:
PTA7/
KBI1P7
PTA6/
KBI1P6
PTA5/
KBI1P5
PTA4/
KBI1P4
PTA3/
KBI1P3
PTA2/
KBI1P2
PTA1/
KBI1P1
PTA0/
KBI1P0
Port B
Bit 7
654321
Bit 0
MCU Pin:
PTB7/
TPM1CH1
PTB6
PTB5
PTB4
PTB3
PTB2
PTB1/
RxD1
PTB0/
TxD1