Altera Avalon Verification IP Suite - Manual (Page 114)

Figure 8-2: Avalon-ST Source Sending Data to a Sink
The following figure illustrates the timing when
READY_LATENCY = 0
.
CLK
ready
valid
data
D1 D2
S
src_dr
S
src_dr
S
src_rdy
S
tc
S
src_~rdy
S
src_~rdy
S
tc
S
src_rdy
T idle T idle T rl_1
Table 8-1: Key to Annotations
The following table explains the annotations used in the figure.
Description Symbol
The idle time before a transactions. This time is set by the command
set_transaction_
idles
.
T
idle
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.
T
rl_1
Signals that the source is driving valid data. The event name is
signal_src_driving_
transaction
.
S
src_dr
Signals the source has received the assertion of ready from the sink. The event name is
signal_src_ready
.
S
src_rdy
Signals the first transaction is complete. The event name is
signal_src_transaction_
complete .
S
tc
Signals the source has received the deassertion of
ready
from the sink. The event name
is
signal_src_not_ready
.
S
src_~rdy
Block Diagram
The following figure provides a block diagram of the Avalon-ST Source BFM. The BFM includes the following
six major blocks:
• Avalon-ST Source API—Provides methods to create Avalon-ST transactions and query the state of all
queues.
• Transaction Descriptor—Accumulates the fields of an Avalon-ST command and inserts completed
commands onto the pending command queue.
• Avalon-ST Physical Driver—Issues transfers and holds each transfer until
ready
is asserted.
• Physical Bus Monitor—Monitors the physical layer and reports on the status of the ready signal to the
Physical Bus Driver and the Public Events module.
• Public Events—Signals the events described in the API.
Avalon-ST Source BFM Altera Corporation
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Block Diagram 8-2