Altera CIC MegaCore Function Manuale Utente Scaricare il pdf (Pagina 28)

Signal Directio

Description

out_endofpacket Output Marks the end of the outgoing result group. If '1', a result

corresponding to channel N-1 is output, where N is the number of

channels.

out_error Output Error signal indicating Avalon-ST protocol violations on source

side:

• 00: No error

• 01: Missing start of packet

• 10: Missing end of packet

• 11: Unexpected end of packet

Other types of errors may also be marked as 11.

out_ready Input Asserted by the downstream module if it is able to accept data.

out_startof-

packet

Output Marks the start of the outgoing result group. If '1', a result

corresponding to channel 0 is output.

out_valid Output Asserted by the IP core when there is valid data to output.

rate Input This signal is available when the variable rate change factor option

is enabled. You can use it to change the decimation or interpola‐

tion rate during run time. It has the size Ceil(log

(maximum rate))

Avalon-ST Interface Data Transfer Timing

Figure 3-7: Avalon-ST Interface Timing with READY_LATENCY=0

0 1 2 3

6 7 84

clk

ready

valid

error

data

00 00 00 00

The source provides data and asserts valid on cycle 1, even though the sink is not ready. The source waits

until cycle 2, when the sink does assert ready, before moving onto the next data cycle. In cycle 3, the

source drives data on the same cycle and because the sink is ready to receive it, the transfer occurs

immediately. In cycle 4, the sink asserts ready, but the source does not drive valid data.

Packet Data Transfers

A beat is the transfer of one unit of data between a source and sink interface. This unit of data may consist

of one or more symbols and makes it is possible to support modules that convey more than one piece of

information about each valid cycle.

Packet data transfers are used for multichannel transfers. Two additional signals (startofpacket and

endofpacket) are defined to implement the packet transfer.

3-12

Avalon-ST Interface Data Transfer Timing

UG-CIC

2014.12.15

Altera Corporation

CIC IP Core Functional Description

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Altera CIC MegaCore Function Manuale Utente Pagina 28

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