Processor Local Bus Functional Model Toolkit User's Manual

Chapter 8. PLB Compliance Checks
8.1 Monitor Model
The PLB monitor model attaches to the PLB bus and generates informational architectural
compliance messages during simulation. The model is passive in that it does not participate in any
bus protocol signal assertions, but it samples PLB signals in every clock to keep track of the state of
the PLB bus and inform the user of any detectable PLB compliance problems. Messages are
generated to the simulator console, which also may be re-directed to file systems in most simulation
environments.
8.2 Terminology
The following terminology is used in the specification of the PLB monitor compliance checks:
• Active: refers to the situation when a signal is at its true state (a logical 1).
• Asserted: refers to the situation when a signal transitions from inactive to its active state.
• Inactive: refers to the situation when a signal is at its false state. (a logical 0)
• Deasserted: refers to the situation when a signal transitions from active to its inactive state.
• Time-out: refers to the event which occurs when there have been 16 cycles of non-response from a
slave (or Mn_abort) since the assertion of PLB_PAValid. The 16 cycle count may be interrupted by
the slave response of Sln_wait active. And the count will remain interrupted for as long as the wait
is active. The count will be terminated by slave asserting Sln_rearbitrate or Sn_addrAck. The count
may also be terminated by the master asserting Mn_abort (given no Sn_addrAck has been
received). If the count reaches 16 and none of the terminating responses (from master or slave)
have been asserted then a time-out has occurred.
8.3 Address Map Set-up Error
An error message is issued when PLB_reset is de-asserted and the PLB monitor slave address map
has not been initialized.
8.4 Slave Interface/PLB Core OR Logic Error
An error message is issued when the OR’ed value of all the PLB slave control outputs does not equal
the output of the system OR gates which are inputs to the PLB arbiter.
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