11/3/95
SECTION 1: OVERVIEW
UM Rev 1
MOTOROLA
MC68349 USER'S MANUAL
v
TABLE OF CONTENTS (Continued)
Paragraph
Page
Number
Title
Number
2.15
Synthesizer Power (VCCSYN) .............................................................. 2-13
2.16
System Power and Ground (VCC) ........................................................ 2-14
2.17
Signal Summary .................................................................................... 2-14
Section 3
Bus Operation
3.1
Bus Transfer Signals ............................................................................. 3-1
3.1.1
Bus Control Signals ........................................................................... 3-2
3.1.2
Function Code Signals ...................................................................... 3-3
3.1.3
Address Bus (A31–A0) ...................................................................... 3-3
3.1.4
Address Strobe (AS).......................................................................... 3-3
3.1.5
Data Bus (D31–D0) ........................................................................... 3-4
3.1.6
Data Strobe (DS ) ............................................................................... 3-4
3.1.7
Bus Cycle Termination Signals.......................................................... 3-4
3.1.7.1
Data Transfer and Size Acknowledge Signals
(DSACK1 and DSACK0) ................................................................ 3-4
3.1.7.2
Bus Error (BERR )........................................................................... 3-4
3.1.7.3
Autovector (AVEC) ......................................................................... 3-5
3.2
Data Transfer Mechanism ..................................................................... 3-5
3.2.1
Dynamic Bus Sizing ........................................................................... 3-5
3.2.2
Misaligned Operands......................................................................... 3-13
3.2.3
Effects of Dynamic Bus Sizing and Operand Misalignment............... 3-20
3.2.4
Bus Operation .................................................................................... 3-20
3.2.5
Synchronous Operation with DSACK≈ .............................................. 3-21
3.2.6
Fast Termination Cycles .................................................................... 3-22
3.3
Data Transfer Cycles ............................................................................ 3-23
3.3.1
Read Cycle ........................................................................................ 3-23
3.3.2
Write Cycle ........................................................................................ 3-28
3.3.3
Read-Modify-Write Cycle................................................................... 3-30
3.4
CPU Space Cycles................................................................................ 3-32
3.4.1
Breakpoint Acknowledge Cycle ......................................................... 3-33
3.4.2
LPSTOP Broadcast Cycle ................................................................. 3-34
3.4.3
Module Base Address Register Access............................................. 3-38
3.4.4
Interrupt Acknowledge Bus Cycles .................................................... 3-38
3.4.4.1
Interrupt Acknowledge Cycle—Terminated Normally .................... 3-38
3.4.4.2
Autovector Interrupt Acknowledge Cycle ....................................... 3-41
3.4.4.3
Spurious Interrupt Cycle ................................................................ 3-41
3.5
Bus Exception Control Cycles ............................................................... 3-43
3.5.1
Bus Errors .......................................................................................... 3-45
3.5.2
Retry Operation ................................................................................. 3-47
3.5.3
Halt Operation.................................................................................... 3-50
3.5.4
Double Bus Fault ............................................................................... 3-52