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

ID 683337
Date 7/15/2024
Public
Document Table of Contents

9.1.8. About the ALU Folding Start of Packet Signal

DSP Builder uses a start of packet signal for systems using ALU folding. The start of packet signal is an extra signal on the ChannelIn and ChannelOut blocks. To use the start of packet signal turn on Has Start of Packet Signal on the ChannelIn and ChannelOut blocks. You must use the start of packet signal for multichannel designs.

With the Start of Packet signal:

  • The system is in an idle state after reset and after it finishes processing a data sample.
  • The system indicates the first clock cycle of a packet of data when the start of packet signal goes high.
  • The system processes the data packet if it is in an idle state when it receives the start of packet signal.
  • The system is not idle the clock cycle after the start of packet signal until it finishes processing a data sample.

You may use the valid signal instead of the start of packet signal, which does not allow the folded system to process a non-valid data sample.