12. Deterministic Latency PHY IP Core
Deterministic latency enables accurate delay measurements and known timing for the transmit (TX) and receive (RX) datapaths as required in applications such as wireless communication systems, emerging Ethernet standards, and test and measurement equipment. The Deterministic Latency PHY IP Core support 1-32 lanes with a continuous range of data rates from 611–6144 Mbps for Arria V devices, 0.6222–6.144 Gbps in Arria V GZ, 611–5000 Mbps in Cyclone V devices, and 611 Mbps–12200 Mbps for Stratix V devices. By setting the appropriate options using the MegaWizard Plug-In Manager, you can configure the Deterministic Latency PHY IP Core to support many industry-standard protocols that require deterministic latency, including the following protocols:
- Common Public Radio Interface (CPRI)
- Open Base Station Architecture Initiative (OBSAI)
- 1588 Ethernet
For more information about using the Deterministic Latency PHY IP Core to implement CPRI, refer to the application note, Implementing the CPRI Protocol Using the Deterministic PHY IP Core.
The following figure illustrates the top-level interfaces and modules of the Deterministic Latency PHY IP Core. As the figure shows, the physical coding sublayer (PCS) includes the following functions:
- TX and RX Phase Compensation FIFO
- Byte serializer and deserializer
- 8B/10B encoder and decoder
- Word aligner
- TX bit slipper
The data that the Deterministic Latency PHY receives data on its FPGA fabric interface employs the Avalon Streaming (Avalon-ST) protocol to transmit and receive data. The Avalon-ST protocol is a simple protocol designed for driving high bandwidth, low latency, unidirectional data. The Deterministic Latency PHY IP Core also includes an Avalon Memory-Mapped (Avalon-MM) interface to access control and status registers. This is a standard, memory-mapped protocol that is normally used to read and write registers and memory. The transceiver reconfiguration interface connects to the Altera Transceiver Reconfiguration Controller IP Core which can dynamically reconfigure transceiver settings. Finally, the PMA transmits and receives serial data.