User`s guide
Address reconstruction overview
When CPU32 microcontrollers are reconfigured, they can present special
problems for debugging. This is especially true when address bits A[19:23]
are reconfigured as chip selects. The HP E2480A Preprocessor Interface
overcomes these problems by using information in the base address register
associated with such chip selects to replace the missing address bits. The
value injected into the signal path depends on which chip select is active.
Refer to chapter 2 for information on programming the preprocessor
interface.
This reconstruction provides many benefits when analyzing a target system:
•
Triggering on address A0 through A23 is possible, even when the upper
address bits are not available from the target microprocessor.
•
The software analyzer, with its increased analysis capabilities, can be used.
•
Code captured in a trace can be correlated with mnemonics in the source
database.
•
Alignment of activity shown in a trace list.
The HP E2480A also reconstructs function control bits FC[0:2] when they are
configured as chip selects, and SIZ[0:1] and DSAck[0:1] when they are
configured as general I/O.
The programming is non-volatile. Once programmed, the HP E2480A does
not need to remain connected to the processor probe to maintain address
reconstruction.
The figure on the following page shows the process by which the HP E2480A
reconstructs addresses.
State and Timing modes use different connectors on the preprocessor
interface. The Timing pins are direct connections to the microcontroller signals.
The State pins have active circuitry on the preprocessor interface. State
information is acquired three target system clock cycles after the same
information is captured in Timing mode.
Reference
Address reconstruction overview
E2480A Motorola CPU32 Preprocessor Interface 4–5