MC9S12A128 Datasheet, PDF (35/92 Pages) Motorola, Inc – Microcontroller unit (MCU)

MC9S12A128 Device Guide — V01.01
2.3.55 PS2 / RXD1 — Port S I/O Pin 2
PS2 is a general purpose input or output pin. It can be configured as the receive pin RXD of Serial
Communication Interface 1 (SCI1).
2.3.56 PS1 / TXD0 — Port S I/O Pin 1
PS1 is a general purpose input or output pin. It can be configured as the transmit pin TXD of Serial
Communication Interface 0 (SCI0).
2.3.57 PS0 / RXD0 — Port S I/O Pin 0
PS0 is a general purpose input or output pin. It can be configured as the receive pin RXD of Serial
Communication Interface 0 (SCI0).
2.3.58 PT[7:0] / IOC[7:0] — Port T I/O Pins [7:0]
PT7-PT0 are general purpose input or output pins. They can be configured as input capture or output
compare pins IOC7-IOC0 of the Enhanced Capture Timer (ECT).
2.4 Power Supply Pins
MC9S12A128 power and ground pins are described below.
NOTE: All V_SS pins must be connected together in the application.
2.4.1 V_DDX, V_SSX — Power & Ground Pins for I/O Drivers
External power and ground for I/O drivers. Because fast signal transitions place high, short-duration
current demands on the power supply, use bypass capacitors with high-frequency characteristics and place
them as close to the MCU as possible. Bypass requirements depend on how heavily the MCU pins are
loaded.
2.4.2 V_DDR, V_SSR — Power & Ground Pins for I/O Drivers & for Internal
Voltage Regulator
External power and ground for I/O drivers and input to the internal voltage regulator. Because fast signal
transitions place high, short-duration current demands on the power supply, use bypass capacitors with
high-frequency characteristics and place them as close to the MCU as possible. Bypass requirements
depend on how heavily the MCU pins are loaded.
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