Question
It looks like the SinCos library requires IQ Math implementation for correct functionality. We are working to incorporate the SinCos library into a larger project that currently uses the FPU without IQ Math. I am unclear on my options here, or the larger impact of including IQ Math into the project. I found this TI support issue: e2e.ti.com/#2240216 which presents a similar concern, however the resolution was not clear to me.
I also found this info on the IQ Math library: IQmath_Library_for_C28x under FAQ stating that there is some compatibility between IQ Math and C28x+FPU. Again, the details here are not completely clear to me and I could use some guidance to make sure we don't back ourselves into a corner with our current project.
Reply:
With the sincos transducer, position measurement comprises two parts:
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The coarse angle, derived from the number of complete sin/cos periods, and
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The fine angle, interpolated within one period and computed using an arctangent.
The first is an integer, the second a float. We need the integer handling capabilities of IQmath to efficiently combine both.
The sincos library is compiled with the MATH_TYPE define in “IQmathLib.h” set to IQ_MATH. This means the IQ functions are called in fixed point mode. This does not impede the use of floating point calculations elsewhere in the program.
