I have some questions in writing 2D FFT code in MPC5775k by using its SPT

1) Use WIN instruction, failed.

// Transfer input vector by PDMA

// 128 x 64-bit real numbers(32bit real,32 bit image), 64-bit PDMA SRAM word holds 2 input points

// Sign Extension,direct, 24 bit complex pack

// VECTOR_LEN = 128 (128 x 2 input points in each), 128 = 0x0080

// SRAM(input_addr) -> OPRAM (0x8000)

0xA1040080, 0xDEADDEAD, 0x80000000, 0x01000001, // test ,move data from SRAM to SPT OPRAM, ok

// FFT 128 RDX4 instruction w/ complex input

// WIN instruction, multiply a constant complex, here is 2 + 0i;

0x86000080, 0x80009000, 0x00000101, 0x00020000, // WIN failed here

// Stop Cmd

0x10000000, 0x00000000, 0x00000000, 0x00000000,

what I want to do is all the data x 2,but failed, why?

2) SPT is fixed point, when I do 2D FFT, the input data is comlex, and its range is -2^23 to +2^23,

Is SPT capable of doing such FFT? I use the real FFT examples provided by NXP FAE, it supports

input data range is 0 ~ 4096(with left shift, unsigned int)

I have implemented real FFT128/256/512/1024, supported input data range is 0 ~ 4096, but get stuck in complex FFT when input data is very large.

3) Where to find complex FFT example for MPC5775K in this forum?

Any help will be very appreciated..

Hi,

this issue is already solved with FAE Jason Yang and automotive experts team.

Regards,

Martin