CCS: _IQ vs Float Point

Mike_3007

Expert 2055 points

Other Parts Discussed in Thread: TMS320F28069M, MOTORWARE

Tool/software: Code Composer Studio

Hi Everyone

First I want to thank you all for your support

I have read C28x IQ – Math Library but a many things I cannot understand at all !

I'm a beginner with this type of data so If somebody could explain to me the advantages and how it can be applied (_IQ) ?

Thanks

Regards

Mike

over 7 years ago

0 Manish Bhardwaj over 7 years ago

TI__Mastermind 43730 points

mike,

which device are you planning on using?

IQ is a way to emulate floating point on a fixed point device.

If you are using floating point device you do not need IQ math lib

0 Ritvik Sadana1 over 7 years ago

TI__Intellectual 835 points

Hi Mike,

This could be a good link to start with: processors.wiki.ti.com/.../IQMath_fixed_vs_floating.pdf

I would then suggest you to try out examples, check their outputs and see how much precision would be suitable for you. A choice between IQ/Floating can be tricky and solely depends on the number of cycles+precision you require.
The pdf covers most of these aspects.

-Ritvik

0 Mike_3007 over 7 years ago in reply to Manish Bhardwaj

Expert 2055 points

I'm using TMS320F28069M. I see many examples of motorware using _IQ that's why I'm a little bit confusing of using it

0 Manish Bhardwaj over 7 years ago in reply to Mike_3007

TI__Mastermind 43730 points

Mike,

yes we use IQ because legacy wise we had to support fixed point devices as well, F2802x and F2803x.

If you are writing new code, I am not sure how much understanding IQ math will be helpfull to you, unless you already understand it :)

On the F28069 the IQ math will not really execute, it will be re-directed to floating point. So even in the code you see IQ, it has no real impact to the code. It helps to use it, because we can run this on F2803x which is a fixed point device.

0 Mike_3007 over 7 years ago in reply to Manish Bhardwaj

Expert 2055 points

Thanks ! I got it

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CCS: _IQ vs Float Point