Visible to Intel only — GUID: jtm1507337780359
Ixiasoft
Visible to Intel only — GUID: jtm1507337780359
Ixiasoft
3.17.2. Extended Delay Measurement for Stratix® 10 Hard FIFOs
The CPRI Intel® FPGA IP uses a dedicated clock, latency_sclk, to measure the delay through the RX and TX Stratix® 10 device hard FIFOs that are configured in the CPRI IP core.
The delay calculation process is identical for the two directions of flow through the IP core; the XCVR_TX_FIFO_DELAY and XCVR_RX_FIFO_DELAY registers hold the same information for the two directions.
To measure the current Tx delay through the hard FIFOs:
- Check the tx_pcs_fifo_delay_valid and tx_core_fifo_delay_valid fields of the XCVR_TX_FIFO_DELAY register at offset 0x84 to ensure the delay count values are updated.
- Add the delay count values in the tx_pcs_fifo_delay and tx_core_fifo_delay fields of the XCVR_TX_FIFO_DELAY register at offset 0x84.
- Multiply the result by the clock period of the latency_sclk.
- Divide this result by 128.
To measure the current Rx delay through the hard FIFOs:
- Check the rx_pcs_fifo_delay_valid and rx_core_fifo_delay_valid fields of the XCVR_RX_FIFO_DELAY register at offset 0x88 to ensure the delay count values are updated.
- Add the delay count values in the rx_pcs_fifo_delay and rx_core_fifo_delay fields of the XCVR_RX_FIFO_DELAY register at offset 0x88.
- Multiply the result by the clock period of the latency_sclk.
- Divide this result by 128.