AN 729: Implementing JESD204B IP Core System Reference Design with Nios II Processor

ID 683844
Date 5/04/2015
Document Table of Contents

1.4.1. Qsys System

The Qsys system is the heart of the reference design, instantiating both the JESD204B IP core data path and the Nios II subsystem control path.

Figure 2. Qsys Subsystem

The top level Qsys system, jesd204b_ed_qsys.qsys, instantiates the following modules:

  • JESD204B subsystem
  • Nios II subsystem
  • Core PLL and PLL reconfiguration controller
  • SPI master

The main data path flows through the JESD204B subsystem. On the RX data path, serial data flows from the external converters to the JESD204B IP core PHY module and out from the JESD204B IP core base module to the transport layer via a 32-bit per transceiver lane Avalon Streaming (Avalon-ST) interface. In this reference design, since there are 4 transceiver lanes (L=4), the total bit width of the Avalon-ST interface is 128 bits.

The control path is centered on the Nios II processor in the Nios II subsystem and connects to various peripherals via the Avalon Memory-Mapped (Avalon-MM) interface. A secondary control path from the SPI master module links out to the SPI configuration interface of external converters via a 4-wire SPI interconnect. The configuration of the external converters is done by writing configuration data from the Nios II processor to the SPI master module. The SPI master module handles the serial transfer of data to the SPI interface on the converter end via the 4-wire SPI interconnect.

The core PLL generates the link clock and frame clock for the system. During a data rate dynamic reconfiguration process, the core PLL is dynamically reconfigurable at run time via the PLL reconfiguration controller. The data rate dynamic reconfiguration process is described in the Data Rate Reconfiguration section.

To view the top level Qsys system in Qsys, follow the steps below:

  1. Launch the Quartus II software.
  2. On the File menu, click Open.
  3. Browse and select the jesd204b_ed_qsys.qsys file located in the project directory.
  4. Click Open to view the QSYS system.

You can access the address mapping of the submodules in the top level Qsys project by clicking on the Address Map tab in the Qsys window.

Figure 3. Address Map View in Qsys

The Qsys system supports multi-link scenarios (up to 16 links) using the existing address map. To add more links to the system, add more jesd204b_subsystem.qsys modules to the project, connect them to the jesd204b_subsystem Avalon-MM bridge, and adjust the address map accordingly. Bits 16-19 of the jesd204b_subsystem Avalon-MM bridge are reserved to support multi-links.

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