Table 3-4 Signal Characteristics (Continued)
Signal
Name
MCU
Module
Signal
Type
Active
State
FC[2:0]
FREEZE
HALT
SIM
SIM
Output
Output
—
1
SIM
Input/Output
Input
0
IC[4:1]
IFETCH
IPIPE
GPT
CPU32
CPU32
SIM
—
Output
—
Output
—
IRQ[7:1]
MISO
Input
0
QSM
SIM
Input/Output
Input
—
MODCLK
MOSI
—
QSM
GPT
GPT
SIM
Input/Output
Output
—
OC[5:1]
PAI
—
Input
—
PC[6:0]
PCS[3:0]
PE[7:0]
PF[7:0]
PGP[7:0]
PQS[7:0]
PCLK
Output
(Port)
—
QSM
SIM
Input/Output
Input/Output
Input/Output
Input/Output
Input/Output
Input
(Port)
(Port)
(Port)
(Port)
—
SIM
GPT
QSM
GPT
GPT
SIM
3
PWMA, PWMB
QUOT
RESET
RMC
Output
—
Output
—
SIM
Input/Output
Output
0
SIM
0
R/W
SIM
Output
1/0
—
RXD
QSM
QSM
SIM
Input
SCK
Input/Output
Output
—
SIZ[1:0]
SS
—
QSM
SIM
Input
0
TSC
Input
—
TXD
QSM
SIM
Output
—
XFC
Input
—
XTAL
SIM
Output
—
Table 3-5 Signal Function
Signal Name
Address Bus
Mnemonic
ADDR[23:0] 24-bit address bus
Function
Address Strobe
Autovector
Bus Error
AS
AVEC
Indicates that a valid address is on the address bus
Requests an automatic vector during interrupt acknowledge
Indicates that a bus error has occurred
BERR
BG
Bus Grant
Indicates that the MCU has relinquished the bus
Indicates that an external device has assumed bus mastership
Signals a hardware breakpoint to the CPU
Bus Grant Acknowledge
Breakpoint
BGACK
BKPT
Bus Request
BR
Indicates that an external device requires bus mastership
System clock output
System Clockout
Chip Selects
CLKOUT
CS[10:0]
CSBOOT
Select external devices at programmed addresses
Chip select for external boot start-up ROM
Boot Chip Select
Data Bus
DATA[15:0] 16-bit data bus
MOTOROLA
3-8
OVERVIEW
MC68331
USER’S MANUAL
MOTOROLA [ MOTOROLA ]
