C5535 - Fixed Point Format

Kevin Rumak

Hey everyone,

New to the DSP world here. I'm thinking about getting a TMDX5535EZDSP kit for modifying the signal coming from a guitar's pickup coils. It's a fixed point DSP, but does anyone know what the fixed point format is? How many bits are associated to each side of the decimal point? I've checked around the docs and couldn't find it.

- Kev

over 11 years ago

0 Archaeologist over 11 years ago

TI__Guru* 84285 points

In principle, you get to decide; for addition, fixed-point is identical to integer arithmetic, except for where you consider the decimal point to be. In practice, it's most natural to use Q15 and Q31 (in TI notation), because the hardware is set up to support these sizes natively, particularly in multiplication; that is, C55x has a Q15 x Q15 -> Q31 multiplication mode ("fractional"). See http://en.wikipedia.org/wiki/Q_%28number_format%29

0 Kevin Rumak over 11 years ago in reply to Archaeologist

Prodigy 60 points

Awesome. Thanks for the help!

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C5535 - Fixed Point Format