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Unread 13-07-2011, 15:00
JamesBrown JamesBrown is offline
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Re: Cartesian to angle

Quote:
Originally Posted by James Critchley View Post
Fantastic!
With the Intel FPU, most modern PC's and Macs will get (0,0) = 0 "right" provided the compiler actually accesses the FPU directly for this calculation (that would be most compilers including gcc). But what does the cRIO do? Is the FPGA intel based? Looks like "Xilinx Virtex" is a custom processor for FPGA? So you need documentation of a firm commitment to define the result as 0, or you need to test and a re-test every time the chip is upgraded which could happen without a "model" change to cRIO.
There seems to be a lot of confusion as to what an FPGA is, specifically what the FPGA in the cRIO is, if anyone is so inclined it may be of value for someone to write up a description about it. It seems that despite being tucked well within NI's system there is a lot of curiosity about it.

To answer quickly FPGA's and processors are inherently different things. an FPGA or field programmable gate array is basically a huge array of gates, basically if you could take millions of nand gates and organize them in an array such that you can combine them in any way you like you would have the functional equivalent of an FPGA. Obviously the execution of an FPGA is a bit mor ecomplicated but you can visualize what is happening this way. By combining the gates in the FPGA in different ways you can create any logic circuits within the chip, including processors. The Xilinx Virtex is simply the family of FPGA's the one on board the cRIO belongs to. Xilinx is the manufacturer, Virtex is the family. Xilinx does have a few different soft core processors (processors created wthin the FPGA) that you can load onto the chip (MicroBlaze, PicoBlaze etc.). I do not howeve know whether these (or any thing simmilar) are implemented in the FPGA, I would guess they are not.
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