Util RFIFO#

The Util RFIFO core is a designed to downscale the clock rate of the TX data path. There are scenarios when the device clock (interface clock) is too high (above 200 MHz), making it a challenge to integrate any processing cores between the device core and UPACK/DMA, because of the small timing margins. By reducing the clock rate of the data path, the user can easily integrate any custom processing core into the design.

To define the correct configuration, the following questions need to be answered:

  1. What is the clock rate of the device core’s data interface? (dout_clk)

  2. What is the data rate of the device core’s data interface? (dout_valid@dout_clk)

  3. What is the targeted clock rate of the data path (din_clk), and how we can achieve it, respecting the main rule of thumb: input data rate must be equal to the output data rate?

If the device clock rate is equal to the device data rate, the only solution to downscale the clock rate is to increase the data width of the output ports of the FIFO. Currently the util_rfifo supports four data width ratios: 1:1/1:2/1:4/1:8.

Features#

  • Supports Altera and AMD Xilinx devices.

  • Downscale the DAC data path’s clock rate.

  • Supports multiple channels (max 8 channels).

Files#

Name

Description

library/util_rfifo/util_rfifo.v

Verilog source for the peripheral.

Block Diagram#

Util RFIFO block diagram

Timing Diagram#

Util RFIFO timing diagram

Configuration Parameters#

Name

Description

Default Value

Choices/Range
NUM_OF_CHANNELS

The number of channels of the device.

 4

DIN_DATA_WIDTH

The bus width of the input data (DMA bus width).

 32

DOUT_DATA_WIDTH

The bus width of the output data (device core’s data interface bus width).

 64

DIN_ADDRESS_WIDTH

The address width of the internal memory of the FIFO.

 8

Interface#

Physical Port

Logical Port

Direction

Dependency
din_clk CLK

in

Physical Port

Logical Port

Direction

Dependency
dout_clk CLK

in

Physical Port

Logical Port

Direction

Dependency
din_rstn RST

in

Physical Port

Logical Port

Direction

Dependency
dout_rst RST

in

Physical Port

Direction

Dependency

Description
din_unf

in

Input data underflow.
dout_unf

out

Output data underflow.
din_enable_*

out

Enable.
din_valid_*

out

Valid.
din_valid_in_*

in

Looped back valid.
din_data_*

in [31:0]

Data.
dout_enable_*

in

Enable.
dout_valid_*

in

Valid.
dout_valid_out_*

out

Looped back valid.
dout_data_*

out [63:0]

Data.

References#