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AR# 16948

LogiCORE CORDIC v2.0 data sheet - Why does Example 5 on Page 8, for the Arctan mode, have the wrong result listed for Pout?

Description

Keywords: CORE Generator, CORDIC, Arctan, Atan, Pout

Why does Example 5 on Page 8, for the Arctan mode, have the wrong result listed for Pout?
Example 5, on page 7, in the CORDIC data sheet shows the following example calculation:

Xin:"0010100000" => 00.10100000 => 0.625
Yin:"0010000000" => 00.10000000 => 0.5
Pout:"0010001100" =>001.0001100 => 1.094

The Arctan of (0.5/0.625) actually works out to be 0.674741.

Solution

This is an error in the data sheet. The core will produce the correct value, in this case:

Pout : 0001010110 => 000.1010110=> 0.672

This is fixed in the v3.0 CORDIC data sheet.

Please see (Xilinx Answer 29570) for a detailed list of LogiCORE CORDIC Release Notes and Known Issues.

AR# 16948
Date Created 09/03/2007
Last Updated 03/27/2009
Status Archive
Type General Article