Avalon Verification IP Suite: User Guide

ID 683439
Date 2/17/2022
Public
Document Table of Contents

8.1. Timing

The following figure illustrates the timing for an Avalon-ST Source BFM sending data to a sink. In the first instance the sink is not ready when the source has data. In the second instance, the sink is ready but the source does not initially have valid data.
Note: The Avalon-ST BFM behaves differently depending on whether the sink’s READY_LATENCY = 0 or READY_LATENCY > 0. When the ready latency is 0, the source BFM holds its current transaction until the sink is ready. When the ready latency is greater than 0, the BFM drives idles until the sink is ready. Then, it drives the transaction.
Figure 13. Avalon-ST Source Sending Data to a SinkThe following figure illustrates the timing when READY_LATENCY = 0.
Table 12.  Key to AnnotationsThe following table explains the annotations used in the figure.
Symbol Description
Tidle The idle time before a transactions. This time is set by the command set_transaction_idles.
Trl_1 The response latency for the first source to sink transaction, which is 3 cycles. The source gets this time using the get_response_latency command.
Ssrc_dr Signals that the source is driving valid data. The event name is signal_src_driving_transaction.
Ssrc_rdy Signals the source has received the assertion of ready from the sink. The event name is signal_src_ready.
Stc Signals the first transaction is complete. The event name is signal_src_transaction_complete.
Ssrc_~rdy Signals the source has received the deassertion of ready from the sink. The event name is signal_src_not_ready.

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