DSP Builder for Intel® FPGAs (Advanced Blockset): Handbook

ID 683337
Date 4/01/2024
Public
Document Table of Contents

12.1.2.4. FIR Filter Reset

When you release the FIR filter from reset after FPGA programming, DSP Builder sets all internal delay-lines to zero.

DSP Builder asserts a valid FIR filter output on the first cycle that the output data includes a contribution from the first valid input. The remaining input contributions come from the internal delay-lines initially set to zero. As valid data input continues to populate the FIR filter, the output evolves to become entirely a function of valid inputs.

In previous versions of DSP Builder, a FIR filter warm reset does not reset internal delay-lines to zero. When DSP Builder first asserts a valid output, the output data incorporates a contribution from the first valid input and the remaining input contributions are from residue within the FIR filter. Again, as valid data input continues to populate the FIR filter, the output evolves to become entirely a function of valid inputs. However, the first outputs, before they are a function of new inputs, have a diminishing residual contribution.

Depending on how you use the FIR filter, this initial post-warm-reset behavior may not be a concern. However, if you require the FIR filter to behave on a warm reset identically to how it behaves when you program the FPGA, turn on the Soft Reset Rezeroes Delay-Lines FIR filter GUI setting. This parameter may cause a resource increase.