TMS320F28374S: FFT usage in VCU

Part Number:TMS320F28374S

Hi Team,

My customer is using VCU(c28x_vcu2_library.lib) FFT feature in solar inverter for data filter, has feedback with some questions, could you kindly help to clarify?

1. Used CFFT_init256Pt、CFFT_run256Pt for 256 FFT analysis, which required the 512 data of array,   if customer only sampled for 256 data in S zone, how to build the 512 array which required?

2. How to using unpack and pack feature? What’s the input and output?

3. What’s the relationship input & output amplitude? For example, if harmonic amplitude is 20 in the input data array 20Khz, what’s the amplitude of 20Khz after FFT conversation?

4. What’s the limitation for S zone and sample point? For example, if the sample frequency is 320KHz, in theory, the calculated frequency can reach to 160Khz no matter with 256 point or 512 point sample?

Expect for your reply, thanks.

Best Regards

Benjamin