Freescale Semiconductor, Inc.
GENERAL RELEASE SPECIFICATION
1.4 Functional Pin Description
8
2
The following paragraphs describe the functionality of each pin on the
MC68HC805P18 package. Pins connected to subsystems described in other
sections provide a reference to the section instead of a detailed functional
description.The pinout is shown in Figure 1-2.
3
28
27
26
25
24
23
22
21
20
19
18
17
16
15
RESET
IRQ
1
4
V
DD
2
OSC1
PA7
3
OSC2
5
PA6
4
PD7/TCAP
TCMP
PA5
5
6
PA4
6
PD5/CKOUT
PC0
PA3
7
PA2
8
PC1
7
PA1
9
PC2
PA0
10
11
12
13
14
PC3/AD3
PC4/AD2
PC5/AD1
PC6/AD0
8
SDO/PB5
SDI/PB6
SCK/PB7
9
V
PC7/V
SS
REFH
10
11
12
13
14
A
Figure 1-2. User Mode Pinout
1.4.1 V and V
DD
SS
Power is supplied to the MCU through V and V . V is connected to a
DD
SS DD
regulated positive supply and V is connected to ground.
SS
Very fast signal transitions occur on the MCU pins. The short rise and fall times
place very high short-duration current demands on the power supply. To prevent
noise problems, take special care to provide good power supply bypassing at the
MCU. Use bypass capacitors with good high-frequency characteristics, and
position them as close to the MCU as possible. Bypassing requirements vary,
depending on how heavily the MCU pins are loaded.
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18
19
20
INTRODUCTION
MC68HC805P18
1-4
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