
MC68331
USER’S MANUAL
OVERVIEW
MOTOROLA
3-7
3
3.4 Signal Descriptions
The following tables define MCU signals.
Table 3-4
shows signal origin, type, and ac-
tive state.
Table 3-5
describes signal functions. Both tables are sorted alphabetically
by mnemonic. MCU pins often have multiple functions. More than one description can
apply to a pin.
1. DATA[15:0] are synchronized during reset only. MODCLK is synchronized only when used as an input port pin.
2. EXTAL, XFC, and XTAL are clock reference connections.
3. PAI and PCLK can be used for discrete input, but are not part of an I/O port.
RXD
SCK
SIZ[1:0]
TSC
TXD
XFC
3
XTAL
3
—
Bo
B
—
Bo
—
—
N
Y
Y
Y
Y
—
—
N
Y
N
Y
Y
—
—
—
I/O
I/O
—
I/O
—
PQS2
PE[7:6]
—
PQS7
—
—
Special
Special
Table 3-3 MCU Power Connections
Pin Mnemonic
V
DDSYN
V
SSE
/V
DDE
V
SS
I/V
DDI
Description
Clock Synthesizer Power
External Periphery Power (Source and Drain)
Internal Module Power (Source and Drain)
Table 3-4 Signal Characteristics
Signal
Name
ADDR[23:0]
AS
AVEC
BERR
BG
BGACK
BKPT
BR
CLKOUT
CS[10:0]
CSBOOT
DATA[15:0]
DS
DSACK[1:0]
DSCLK
DSI
DSO
EXTAL
MCU
Module
SIM
SIM
SIM
SIM
SIM
SIM
CPU32
SIM
SIM
SIM
SIM
SIM
SIM
SIM
CPU32
CPU32
CPU32
SIM
Signal
Type
Bus
Output
Input
Input
Output
Input
Input
Input
Output
Output
Output
Bus
Output
Input
Input
Input
Output
Input
Active
State
—
0
0
0
0
0
0
0
—
0
0
—
0
0
Serial Clock
(Serial Data)
(Serial Data)
—
Table 3-2 MCU Pin Characteristics (Continued)
Pin
Mnemonic
Output
Driver
Input
Synchronized
Input
Hysteresis
Discrete
I/O
Port
Designation