Datasheet

General Description
Pin Functions
MC68HC908GR8 — Rev 4.0 Technical Data
MOTOROLA General Description 31
Figure 1-3. DIP And SOIC Pin Assignments
1.6 Pin Functions
Descriptions of the pin functions are provided here.
1.6.1 Power Supply Pins (V
DD
and V
SS
)
V
DD
and V
SS
are the power supply and ground pins. The MCU operates
from a single power supply.
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 1-4
shows. Place the C1 bypass capacitor as close to the MCU as possible.
Use a high-frequency-response ceramic capacitor for C1. C2 is an
optional bulk current bypass capacitor for use in applications that require
the port pins to source high current levels.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CGMXFC
OSC2
OSC1
RST
PTE0/TxD
PTE1/RxD
IRQ
PTD0/SS
PTD1/MISO
PTD2/MOSI
PTD3/SPSCK
V
SS
V
DD
PTD4/T1CH0
V
SSA
V
DDA
PTA3/KBD3
PTA2/KBD2
PTA1/KBD1
PTA0/KBD0
V
SSAD
/V
REFL
V
DDAD
/V
REFH
PTB3/AD3
PTB2/AD2
PTB1/AD1
PTB0/AD0
PTD6/T2CH0
PTD5/T1CH1
NOTE: Ports PTB4, PTB5, PTC0, and PTC1 are available only with the QFP.
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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