A basic MC68040 bus cycle starts with the transfer start signal, TS. The TS signal
pulses low for about one clock cycle. Another signal, transfer in progress TIP stays
low throughout the cycle, but is not necessarily deasserted between cycles. The end
of the cycle occurs when the processor samples a transfer acknowledge TA or a
transfer error acknowledge TEA or both on the rising edge of the clock. Because of
the nature of these signals, most systems are synchronous to the clock. The typical
system will sample TS on the rising clock edge and then generate a TA signal an
intregal number of clocks later. Wait states are added to a cycle by delaying when
the TA is asserted.
If the emulator is configured for wait states (BCLK >25 MHz), then a compatibility
problem with the emulator may be stalling the processor.
w>cf
cf cache=en
cf mmu=en
cf mon=none
cf rrt=dis
cf ti=en
cf wait=en <- configuration for wait states
w>
The emulator requires at least one wait state in all bus cycles when it is configured
as above. The emulator does not add this wait state, but will not accept a TA from
the target system until after a wait state has been added. If TA is asserted by the
target system during the wait state period and is then deasserted before the emulator
allows termination, the bus cycle will never complete.
This particular example can be easily duplicated on the demo board by configuring
for wait states and interlocking memory to the demo board.
cf wait=en
map 0..0ff eram lock
r rst
If there is no functional reason why the bus cycle would not complete, check the
timing relationships between the various bus cycle control signals. Probably the
first measurement you will want to make is to see if the setup time of TA to BCLK
is within the emulator specification.
If there are no cycles in the trace list, then the processor stopped during the first bus
cycle. In this case, it is pretty easy to set up the trace using TS as the trigger
because the cycle of interest is the first cycle. If there are only a few cycles in the
trace list, the same technique can be used if the oscilloscope or timing analyzer has
enough depth.
Chapter 18: Connecting the Emulator to a Target System
Verifying Operation Of The Emulator In Your Target System
625
Summary of Contents for 64783A
Page 30: ...xxx ...
Page 31: ...Part 1 Quick Start Guide 1 ...
Page 33: ...1 Getting Started 3 ...
Page 70: ...40 ...
Page 75: ...Part 2 Using The Emulator 45 ...
Page 140: ...110 ...
Page 141: ...4 Using the Emulator How to control the processor and view system resources 111 ...
Page 227: ...5 Using the Emulation Bus Analyzer How to record program execution in real time 197 ...
Page 290: ...260 ...
Page 331: ...8 Configuring the Emulator 301 ...
Page 382: ...352 ...
Page 383: ...9 Solving Problems What to do when the emulator doesn t behave as expected 353 ...
Page 397: ...Part 3 Reference 367 ...
Page 399: ...10 Using Memory Management Understanding logical and physical emulation and analysis 369 ...
Page 429: ...11 Emulator Commands The command syntax reference for the emulator softkey interface 399 ...
Page 443: ...copy Chapter 11 Emulator Commands copy 413 ...
Page 451: ...display Chapter 11 Emulator Commands display 421 ...
Page 457: ...DISPLAY MEMORY Chapter 11 Emulator Commands DISPLAY MEMORY 427 ...
Page 461: ...DISPLAY MMU Chapter 11 Emulator Commands DISPLAY MMU 431 ...
Page 464: ...DISPLAY TRACE Chapter 11 Emulator Commands DISPLAY TRACE 434 ...
Page 480: ...modify Chapter 11 Emulator Commands modify 450 ...
Page 501: ...set Chapter 11 Emulator Commands set 471 ...
Page 514: ... SYMB Chapter 11 Emulator Commands SYMB 484 ...
Page 582: ...552 ...
Page 583: ...13 Setting X Resources 553 ...
Page 598: ...568 ...
Page 606: ...576 ...
Page 613: ...16 Specifications and Characteristics 583 ...
Page 627: ...Part 4 Concept Guide 597 ...
Page 629: ...17 X Resources and the Graphical User Interface 599 ...
Page 639: ...Part 5 Installation and Service Guide 609 ...
Page 697: ...19 Installation and Service 667 ...
Page 746: ...Chapter 19 Installation and Service Verifying the Installation 716 ...
Page 755: ...20 Installing Updating Emulator Firmware 725 ...
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Page 810: ...X server 554 604 X Window System 54 Index 780 ...