Intel® Quartus® Prime Pro Edition User Guide: Platform Designer

ID 683609
Date 10/04/2021
Public

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6.7.3. Avalon® Streaming Round Robin Scheduler IP Operation

If a particular channel is almost full, the Avalon® Streaming Round Robin Scheduler does not schedule data to be read from that channel in the source component.

The scheduler only requests 1 bit of data from a channel at each transaction. To request 1 bit of data from channel n, the scheduler writes the value 1 to address (4 ×n). For example, if the scheduler is requesting data from channel 3, the scheduler writes 1 to address 0xC. At every clock cycle, the scheduler requests data from the next channel. Therefore, if the scheduler starts requesting from channel 1, at the next clock cycle, it requests from channel 2. The scheduler does not request data from a particular channel if the almost-full status for the channel is asserted. In this case, the scheduler uses one clock cycle without a request transaction.

The Avalon® Streaming Round Robin Scheduler cannot determine if the requested component is able to service the request transaction. The component asserts waitrequest when it cannot accept new requests.

Table 183.   Avalon® Streaming Round Robin Scheduler Ports

Signal

Direction

Description

Clock and Reset

clk

In

Clock reference.

reset_n

In

Asynchronous active low reset.

Avalon® Memory Mapped Request Interface

request_address (log2 Max_Channels–1:0)

Out

The write address that indicates which channel has the request.

request_write

Out

Write enable signal.

request_writedata

Out

The amount of data requested from the particular channel.

This value is always fixed at 1.

request_waitrequest

In

Wait request signal that pauses the scheduler when the agent cannot accept a new request.

Avalon® Streaming Almost-Full Status Interface

almost_full_valid

In

Indicates that almost_full_channel and almost_full_data are valid.

almost_full_channel (Channel_Width–1:0)

In

Indicates the channel for the current status indication.

almost_full_data (log2 Max_Channels–1:0)

In

A 1-bit signal that is asserted high to indicate that the channel indicated by almost_full_channel is almost full.