CPRI Intel® FPGA IP User Guide

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ID 683595
Date 5/19/2023
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Document Table of Contents
Document Table of Contents x
1. About the CPRI Intel® FPGA IP Core 2. Getting Started with the CPRI Intel® FPGA IP Core 3. Functional Description 4. CPRI Intel® FPGA IP Core Signals 5. CPRI Intel® FPGA IP Core Registers 6. CPRI Intel® FPGA IP User Guide Archives 7. Document Revision History for the CPRI Intel® FPGA IP User Guide
1. About the CPRI Intel® FPGA IP Core x
1.1. CPRI Intel® FPGA IP Core Supported Features 1.2. CPRI Intel® FPGA IP Core Device Family and Speed Grade Support 1.3. Intel® FPGA IP Core Verification 1.4. Resource Utilization for CPRI Intel® FPGA IP Core 1.5. Release Information
1.2. CPRI Intel® FPGA IP Core Device Family and Speed Grade Support x
1.2.1. Device Family Support 1.2.2. CPRI Intel® FPGA IP Core Performance: Device and Transceiver Speed Grade Support
2. Getting Started with the CPRI Intel® FPGA IP Core x
2.1. Installation and Licensing 2.2. Generating CPRI Intel® FPGA IP Core 2.3. CPRI Intel® FPGA IP File Structure 2.4. CPRI Intel® FPGA IP Core Parameters 2.5. Integrating Your Intel® FPGA IP Core in Your Design: Required External Blocks 2.6. Simulating Intel FPGA IP Cores 2.7. Understanding the Testbench 2.8. Running the Design Example 2.9. Compiling the Full Design and Programming the FPGA
2.1. Installation and Licensing x
2.1.1. Intel® FPGA IP Evaluation Mode
2.5. Integrating Your Intel® FPGA IP Core in Your Design: Required External Blocks x
2.5.1. Adding the Transceiver TX PLL IP Core 2.5.2. System PLL Connections for the Intel Agilex® 7 F-tile Variations 2.5.3. Adding the Reset Controller 2.5.4. Adding the Transceiver Reconfiguration Controller 2.5.5. Adding the Off-Chip Clean-Up PLL 2.5.6. Adding and Connecting the Single-Trip Delay Calibration Blocks 2.5.7. Transceiver PLL Calibration 2.5.8. Reference and System PLL Clock for your IP Design
3. Functional Description x
3.1. Interfaces Overview 3.2. CPRI Intel® FPGA IP Core Clocking Structure 3.3. CPRI Intel® FPGA IP Core Reset Requirements 3.4. Start-Up Sequence Following Reset 3.5. AUX Interface 3.6. Direct IQ Interface 3.7. Ctrl_AxC Interface 3.8. Direct Vendor Specific Access Interface 3.9. Real-Time Vendor Specific Interface 3.10. Direct HDLC Serial Interface 3.11. Direct L1 Control and Status Interface 3.12. L1 Debug Interface 3.13. Media Independent Interface (MII) to External Ethernet Block 3.14. Gigabit Media Independent Interface (GMII) to External Ethernet Block 3.15. CPU Interface to CPRI Intel® FPGA IP Registers 3.16. Auto-Rate Negotiation 3.17. Extended Delay Measurement 3.18. Deterministic Latency and Delay Measurement and Calibration 3.19. CPRI Intel® FPGA IP Transceiver and Transceiver Management Interfaces 3.20. Testing Features
3.2. CPRI Intel® FPGA IP Core Clocking Structure x
3.2.1. Example CPRI Intel® FPGA IP Core Clock Connections in Different Clocking Modes
3.4. Start-Up Sequence Following Reset x
3.4.1. Start-Up Sequence Interface Signals
3.5. AUX Interface x
3.5.1. AUX Interface Signals 3.5.2. AUX Interface Synchronization 3.5.3. Auxiliary Latency Cycles 3.5.4. Direct Interface CPRI Frame Data Format
3.14. Gigabit Media Independent Interface (GMII) to External Ethernet Block x
3.14.1. GMII Normal Mode 3.14.2. Ethernet PCS Bypass Mode 3.14.3. Ethernet PCS Run-Time Switching
3.15. CPU Interface to CPRI Intel® FPGA IP Registers x
3.15.1. CPU Interface Signals 3.15.2. Accessing the Hyperframe Control Words
3.15.2. Accessing the Hyperframe Control Words x
3.15.2.1. Specifying the Control Word 3.15.2.2. Specifying the Position in the Control Word 3.15.2.3. Retrieving the Hyperframe Control Words 3.15.2.4. Writing the Hyperframe Control Words
3.17. Extended Delay Measurement x
3.17.1. Extended Delay Measurement for Soft Internal Buffers 3.17.2. Extended Delay Measurement for Intel® Stratix® 10 Hard FIFOs 3.17.3. Extended Delay Measurement Interface
3.18. Deterministic Latency and Delay Measurement and Calibration x
3.18.1. Delay Measurement and Calibration Features 3.18.2. Delay Requirements 3.18.3. Single-Hop Delay Measurement 3.18.4. Multi-Hop Delay Measurement 3.18.5. Delay Calibration Features
3.18.3. Single-Hop Delay Measurement x
3.18.3.1. Rx Path Delay 3.18.3.2. Tx Path Delay 3.18.3.3. Round-Trip Delay
3.18.5. Delay Calibration Features x
3.18.5.1. Single-Trip Delay Calibration 3.18.5.2. Round-Trip Delay Calibration 3.18.5.3. Tx Bitslip Delay
3.18.5.1. Single-Trip Delay Calibration x
3.18.5.1.1. Single-Trip Latency Measurement and Calibration Interface Signals
3.19. CPRI Intel® FPGA IP Transceiver and Transceiver Management Interfaces x
3.19.1. CPRI Link 3.19.2. Main Transceiver Clock and Reset Signals 3.19.3. Arria V, Arria V GZ, Cyclone V, and Stratix V Transceiver Reconfiguration Interface 3.19.4. Intel® Arria® 10, Intel® Stratix® 10, and Intel Agilex® 7 Transceiver Reconfiguration Interface 3.19.5. RS-FEC Interface 3.19.6. Interface to the External Reset Controller 3.19.7. Interface to the External PLL 3.19.8. Transceiver Debug Interface
3.20. Testing Features x
3.20.1. CPRI Intel® FPGA IP Core Loopback Modes 3.20.2. CPRI Intel® FPGA IP Core Self-Synchronization Feature
4. CPRI Intel® FPGA IP Core Signals x
4.1. CPRI Intel® FPGA IP Core L2 Interface 4.2. CPRI Intel® FPGA IP Core L1 Direct Access Interfaces 4.3. CPRI Intel® FPGA IP Core Management Interfaces 4.4. CPRI Intel® FPGA IP Core Transceiver and Transceiver Management Signals
1. About the CPRI Intel® FPGA IP Core
2. Getting Started with the CPRI Intel® FPGA IP Core
3. Functional Description
4. CPRI Intel® FPGA IP Core Signals
5. CPRI Intel® FPGA IP Core Registers
6. CPRI Intel® FPGA IP User Guide Archives
7. Document Revision History for the CPRI Intel® FPGA IP User Guide

3.18.5.3. Tx Bitslip Delay

To increase the consistency of the round-trip delay, the CPRI RE slave introduces a variable bitslip on the Tx path to complement the variability in the word aligner in the transceiver on the Rx path.

The CPRI Intel® FPGA IP core reports the Rx bitslip through the word aligner in the rx_bitslip_out field of the XCVR_BITSLIP register, and compensates for the variable delay by adding a bitslip in the Tx path. The current size of this bitslip in bits is available in the tx_bitslip_in field of the XCVR_BITSLIP register. When you leave the tx_bitslip_en field at its default value of 0, this feature is active.

The Tx bitslip feature ensures stability in the round-trip delay through a CPRI RE core, but introduces a variable component in each of the Tx and Rx paths when considered independently. In CPRI IP cores in master clocking mode, the rx_bitslip_out field has the constant value of 0.

If you set the value of the tx_bitslip_en field to 1, you can override the current rx_bitslip_out value to control the Tx bitslip delay manually. Intel® does not recommend implementing the manual override.

In CPRI IP variations that target an Arria V, Cyclone V, or Stratix V device, the Tx bitslip functionality is included in the Transceiver PHY Intel® FPGA IP core that is generated with the CPRI Intel® FPGA IP. These variations include the XCVR_BITSLIP register to support manual override of the Tx bitslip delay.

Note: Intel® does not recommend implementing the manual override for the Tx bitslip.

The total of the Tx bitslip delay and the word aligner bitslip delay in the transceiver receiver is added to the detailed round-trip delay calculation as part of the Tx and Rx transceiver delays. However, the total of these two bit values does not reach the duration of a single cpri_clkout cycle, nor does it reach the threshold of the CPRI specification R-20 and R-21 requirements. The bitslip delay is noticeable only with an oscilloscope.

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