Table 3-2 MCU Pin Characteristics (Continued)
Pin
Mnemonic
Output
Driver
Input
Synchronized
Input
Hysteresis
Discrete
I/O
Port
Designation
RXD
SCK
—
Bo
B
N
Y
N
Y
—
I/O
—
PQS2
PE[7:6]
—
SIZ[1:0]
TSC
Y
N
Y
I/O
—
Bo
—
—
Y
—
TXD
Y
Y
I/O
PQS7
—
3
XFC
—
—
—
—
Special
Special
3
—
XTAL
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.
Table 3-3 MCU Power Connections
Pin Mnemonic
Description
V
Clock Synthesizer Power
DDSYN
V
/V
External Periphery Power (Source and Drain)
Internal Module Power (Source and Drain)
SSE DDE
V
I/V
SS DDI
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.
Table 3-4 Signal Characteristics
Signal
Name
MCU
Module
Signal
Type
Active
State
ADDR[23:0]
AS
SIM
SIM
Bus
Output
Input
—
0
AVEC
SIM
0
BERR
SIM
Input
0
BG
SIM
Output
Input
0
BGACK
BKPT
SIM
0
CPU32
SIM
Input
0
BR
Input
0
CLKOUT
CS[10:0]
CSBOOT
DATA[15:0]
DS
SIM
Output
Output
Output
Bus
—
SIM
0
SIM
0
SIM
—
SIM
Output
Input
0
DSACK[1:0]
DSCLK
DSI
SIM
0
CPU32
CPU32
CPU32
SIM
Input
Serial Clock
(Serial Data)
(Serial Data)
—
Input
DSO
Output
Input
EXTAL
MC68331
OVERVIEW
MOTOROLA
3-7
USER’S MANUAL
MOTOROLA [ MOTOROLA ]
