Hi !

I'm looking for FFT accelerator with 21489.

I only found an IIR Accelerator example in .**..\Analog Devices\VisualDSP 5.0\214xx\Examples\ADSP-21489 EZ-Board**.

Is there a way to have an example with FFT ?

Then, I would like to compare with and without accelerator. How can we bypass the accelerator in this example ?

Hi Pereira,

While looking into the programing model (page no: 386 /1304) for FFT given in the Hardware reference manual, you can clearly understand that how to program the FFTCTL2 register with required values. Its mentioned that, the value of VDIM and LOG2VDIM should be as follows.

VDIM= N/16

LOG2VDIM= Log2(N)

where the 'N' is the number of FFT points .

In 256 point FFT example, the value of N is 256 ( N = 256 points), hence the value of VDIM is calculated as 16 (VDIM = 256/16) and FFT_LOG2VDIM is calculated as 8 (LOG2VDIM = Log2(256)). For detailed information about the FFT Accelerator you can refer to the "FFT Accelerator" chapter given in the 'ADSP-214xx SHARC Processor Hardware Reference' manual.

So its indeed to be a mistake in the 'FFTCTL2 Register Bit Descriptions' of the hardware reference manual. Thanks for bringing this in our notice, we will make sure that this will be corrected in the future updates.

Regards,

Jithul