Xilinx V2.1 manual Math, Accumulator, Xilinx LogiCORE, Block Interface, Xilinx Blocks

Models: V2.1

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Math

Xilinx Blocks

Polyphase behavior: Decimation, Interpolation, Single rate.

Latency: specify input sample period latency.

Hardware Over-Sampling Rate: Hardware clocks per sample. This affects hardware implementation only, and has no effect on simulation. In multi-channel mode, this factor will multiply the implicit oversampling factor.

Other parameters used by this block are explained in the Common Parameters section of the previous chapter.

The FIR filter block cannot be placed in an enabled subsystem in System Generator v2.1. See the Enabled Subsystems section (within the MATLAB I/O library documentation) explanation for more details.

Xilinx LogiCORE

The block always uses the Xilinx LogiCORE Distributed Arithmetic FIR Filter V6.0.

The Simulink model operates on a sample in/sample out basis, but the core has the capability of using serial arithmetic by overclocking. Although this adds latency, it has the benefit of reducing the hardware required for the filter. Refer to the core datasheet for more details of the filter modes and parameters.

The core datasheet can be found on your local disk at:

%XILINX%\coregen\ip\xilinx\eip1\com\xilinx\ip\da_fir_v6_0\doc\ da_fir.pdf

Math

The Math section of the Xilinx Blockset contains mathematical functions.

Accumulator

The Xilinx Accumulator block implements an adder or subtractor based scaling accumulator. The block’s current input is accumulated with a scaled current stored value. The scale factor is a block parameter.

Block Interface

The block has an input b, a reset rst, and an output q. The output must have the same width as the input data. The output q is calculated as follows:

The output must have the same arithmetic type as the input. The block has latency of one sample period.

A subtractor based accumulator replaces addition of the current input b(n) with subtraction. The output will have the same arithmetic type and binary point position as the input. The block always has a latency of one sample period.

Math

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Page 81
Image 81
Xilinx V2.1 manual Math, Accumulator, Xilinx LogiCORE, Block Interface, Xilinx Blocks