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