uvm: basic sequences

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May 2015

UVM: Basic Sequences Chandra Bhushan Singh

Topics Covered •  Sequence Item •  Sequencer •  Sequences

2 Arrow Devices Pvt Ltd

Sequence Item

Arrow Devices Pvt Ltd

Sequence Item Content

Sequence Item consists of the following

Ø  Control : What type of transfer, what size

Ø  Payload : The main data content of the transfer

Ø  Configuration : Setting up a new mode of operation,

error behavior etc

Ø  Analysis : Convenience fields which aid analysis - time

stamps, rolling checksums etc



Randomiza7on Considera7ons

Ø  Request properties should be rand Ø  Response properties should not be rand

Example: Sequence Item



Sequence Item Methods

Sequencer



Sequencer Characteris7cs

Sequencer has the following characteristics: Ø  Provides coordination between sequence

and driver Ø  Sends transactions to driver Ø  Gets the response from the driver Ø  Responsible for arbitrating between the

parallel sequences


Sequencer-‐Driver Connec7on


UVM Sequencer API API’s Supported by UVM Sequencer Ø  get_next_item Ø  try_next_item Ø  item done Ø  peek Ø  get Ø  put


Recommended Driver-‐Sequencer API

Ø  get_next_item() followed by item_done() Ø  get(req) followed by put(rsp)

1

2


“get_next_item()” followed by “item_done()”

1


“get(req)” followed by “put(rsp)” 2


Sequences


Sequences

Ø  Derived from an uvm_sequence_item Ø  Parameterized with the type of seq_item Ø  Body method Ø  m_sequencer handle

Sequences have the following characteristics:


Example: Sequences


Running a Sequence

Ø  Step 1: Create Sequence

Ø  Step 2: Configure Sequence

Ø  Step 3: Start the Sequence


Step 1: Create Sequence


Step 2: Configure Sequence

Ø  Set up start values Ø  Set up generation loop variables Ø  Set up pointers to test-bench

resources


Step 3: Start Sequence

•  Call to its start() method


Sequence Item To A Driver: The Flow

Ø  Creation of seq item Ø  Ready - start_item() Ø  Set - Randomization Ø  Go - finish_item() Ø  Response - get_response()


Sequence Execu7on Flow

Sequences have two types of execution Ø  Linear Execution Flow Ø  Parallel Execution Flow


Coding Guideline

Ø  Do not use fork, join_any, disable fork Ø  Do not use fork join_none to exit a body

method Ø  Do not fork join a sequence which

contains a forever loop without terminating condition


Sequences Overrides

Two types of overrides: Ø  Sequence Type Factory Override Ø  Sequence Instance Factory Override


Sequence Type Factory Override


Sequence Instance Factory Override

Thank you


uvm: basic sequences

Engineering