MC908AP32CFBE Datasheet, PDF (26/324 Pages) Freescale Semiconductor, Inc – The following revision history table summarizes changes contained in this document. For your convenience, the page number designators have been linked to the appropriate location.

General Description
Table 1-2. Pin Functions
PIN NAME
PIN DESCRIPTION
8-bit general purpose I/O port; PTB0–PTB3 are open drain when
configured as output. PTB4–PTB7 have schmitt trigger inputs.
PTB0/SDA
PTB1/SCL
PTB2/TxD
PTB3/RxD
PTB4/T1CH0
PTB5/T1CH1
PTB6/T2CH0
PTB7/T2CH1
PTB0 as SDA of MMIIC.
PTB1 as SCL of MMIIC.
PTB2 as TxD of SCI; open drain output.
PTB3 as RxD of SCI.
PTB4 as T1CH0 of TIM1.
PTB5 as T1CH1 of TIM1.
PTB6 as T2CH0 of TIM2.
PTB7 as T2CH1 of TIM2.
8-bit general purpose I/O port; PTC6 and PTC7 are open drain
when configured as output.
PTC0/IRQ2
PTC1
PTC2/MISO
PTC3/MOSI
PTC4/SS
PTC5/SPSCK
PTC6/SCTxD
PTC7/SCRxD
PTC0 is shared with IRQ2 and has schmitt trigger input.
PTC2 as MISO of SPI.
PTC3 as MOSI of SPI.
PTC4 as SS of SPI.
PTC5 as SPSCK of SPI.
PTC6 as SCTxD of IRSCI; open drain output.
PTC7 as SCRxD of IRSCI.
PTD0/KBI0
:
PTD7/KBI7
8-bit general purpose I/O port with schmitt trigger inputs.
Pins as keyboard interrupts (with pullup), KBI0–KBI7.
1. See Chapter 22 Electrical Specifications for V_REG tolerance.
IN/OUT
In/Out
In/Out
In/Out
Out
In
In/Out
In/Out
In/Out
In/Out
In/Out
In
In
Out
In
In/Out
Out
In
In/Out
In
VOLTAGE
LEVEL
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
V_DD
1.6 Power Supply Bypassing (VDD, VDDA, VSS, VSSA)
V_DD and V_SS are the power supply and ground pins, the MCU operates from a single power supply
together with an on chip voltage regulator.
Fast signal transitions on MCU pins place high. short-duration current demands on the power supply. To
prevent noise problems, take special care to provide power supply bypassing at the MCU as Figure 1-5
shows. Place the bypass capacitors as close to the MCU power pins as possible. Use
high-frequency-response ceramic capacitor for C_BYPASS, C_BULK are optional bulk current bypass
capacitors for use in applications that require the port pins to source high current level.
MC68HC908AP Family Data Sheet, Rev. 4
26
Freescale Semiconductor