FIFO Intel® FPGA IP User Guide

ID 683522
Date 7/08/2024
Public

1.8. SCFIFO and DCFIFO Show-Ahead Mode

You can set the read request/rdreq signal read access behavior by selecting normal or show-ahead mode.

For normal mode, the FIFO Intel® FPGA IP core treats the rdreq port as a normal read request that only performs read operation when the port is asserted.

For show-ahead mode, the FIFO Intel® FPGA IP core treats the rdreq port as a read-acknowledge that automatically outputs the first word of valid data in the FIFO Intel® FPGA IP core (when the empty is low) without asserting the rdreq signal. Asserting the rdreq signal causes the FIFO Intel® FPGA IP core to output the next data word, if available.

Figure 5. Normal Mode Waveform

Data appears after the rdreq asserted.

Figure 6. Show-Ahead Mode Waveform

Data appears before the rdreq asserted.