Table 3-1 MCU Driver Types
Type
A
I/O
O
Description
Output-only signals that are always driven; no external pull-up required
Type A output with weak P-channel pull-up during reset
Aw
B
O
O
Three-state output that includes circuitry to pull up output before high impedance is
established, to ensure rapid rise time. An external holding resistor is required to maintain
logic level while the pin is in the high-impedance state.
Bo
O
Type B output that can be operated in an open-drain mode
Table 3-2 MCU Pin Characteristics
Pin
Mnemonic
Output
Driver
Input
Synchronized
Input
Hysteresis
Discrete
I/O
Port
Designation
ADDR23/CS10/ECLK
ADDR[22:19]/CS[9:6]
ADDR[18:0]
AS
A
A
Y
Y
N
N
O
O
—
PC[6:3]
—
A
Y
N
—
I/O
I/O
—
—
—
—
—
—
—
—
I/O
I/O
I/O
—
—
—
O
B
Y
N
PE5
PE2
—
AVEC
B
Y
N
BERR
B
Y
N
BG/CS1
B
—
Y
—
N
—
3
BGACK/CS2
BKPT/DSCLK
BR/CS0
B
—
—
B
Y
Y
—
Y
N
—
CLKOUT
A
—
—
Y
—
—
N
—
CSBOOT
DATA[15:0]1
DS
B
—
Aw
B
—
Y
N
PE4
PE1
PE0
—
DSACK1
B
Y
N
DSACK0
B
Y
N
DSI/IFETCH
DSO/IPIPE
EXTAL2
A
Y
Y
A
—
—
Y
—
Special
N
—
—
A
—
FC[2:0]/CS[5:3]
FREEZE/QUOT
IC4/OC5
PC[2:0]
—
A
—
Y
—
Y
—
I/O
I/O
—
I/O
I/O
I/O
I/O
I/O
I
A
GP4
GP[7:5]
—
IC[3:1]
A
Y
Y
HALT
Bo
B
Y
N
IRQ[7:1]
Y
Y
PF[7:1]
PQS0
PF0
PQS1
GP[3:0]
—
MISO
Bo
B
Y
Y
1
MODCLK
Y
N
MOSI
Bo
A
Y
Y
OC[4:1]
Y
Y
2
PAI
—
—
Bo
Bo
A
Y
Y
2
Y
Y
I
—
PCLK
PCSO/SS
PCS[3:1]
PWMA, PWMB
R/W
Y
Y
I/O
I/O
O
PQS3
PQS[6:4]
—
Y
Y
—
Y
—
N
A
—
—
I/O
—
RESET
Bo
B
Y
Y
—
RMC
Y
N
PE3
MOTOROLA
3-6
OVERVIEW
MC68331
USER’S MANUAL
MOTOROLA [ MOTOROLA ]
