R-tile Avalon® Streaming Intel® FPGA IP for PCI Express* Design Example User Guide

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ID 683544
Date 12/13/2021
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Document Table of Contents
Document Table of Contents x
1. Design Example Description 2. Quick Start Guide 3. R-Tile Avalon® Streaming Intel® FPGA IP for PCI Express* Design Example User Guide Archives 4. Document Revision History for the R-tile Avalon® Streaming Intel FPGA IP for PCI Express Design Example User Guide
1. Design Example Description x
1.1. Credit Initialization Sequence
1.1. Credit Initialization Sequence x
1.1.1. Credit Value Initialization and Return 1.1.2. Credit Distribution
2. Quick Start Guide x
2.1. Directory Structure 2.2. Generating the Design Example 2.3. Simulating the Design Example 2.4. Root Port BFM 2.5. Compiling the Design Example 2.6. Running the Design Example
2.3. Simulating the Design Example x
2.3.1. Testbench
2.3.1. Testbench x
2.3.1.1. Testbench Modules 2.3.1.2. Test Driver Module 2.3.1.3. PIO Design Example
2.4. Root Port BFM x
2.4.1. BFM Memory Map 2.4.2. Configuration Space Bus and Device Numbering 2.4.3. Configuration of Root Port and Endpoint 2.4.4. Issuing Read and Write Transactions to the Application Layer 2.4.5. BFM Procedures and Functions
2.4.5. BFM Procedures and Functions x
2.4.5.1. ebfm_barwr Procedure 2.4.5.2. ebfm_barwr_imm Procedure 2.4.5.3. ebfm_barrd_wait Procedure 2.4.5.4. ebfm_barrd_nowt Procedure 2.4.5.5. ebfm_cfgwr_imm_wait Procedure 2.4.5.6. ebfm_cfgwr_imm_nowt Procedure 2.4.5.7. ebfm_cfgrd_wait Procedure 2.4.5.8. ebfm_cfgrd_nowt Procedure 2.4.5.9. BFM Configuration Procedures 2.4.5.10. BFM Shared Memory Access Procedures 2.4.5.11. BFM Log and Message Procedures 2.4.5.12. Verilog HDL Formatting Functions
2.4.5.9. BFM Configuration Procedures x
2.4.5.9.1. ebfm_cfg_rp_ep Procedure 2.4.5.9.2. ebfm_cfg_decode_bar Procedure
2.4.5.10. BFM Shared Memory Access Procedures x
2.4.5.10.1. Shared Memory Constants 2.4.5.10.2. shmem_write Task 2.4.5.10.3. shmem_read Function 2.4.5.10.4. shmem_display Verilog HDL Function 2.4.5.10.5. shmem_fill Procedure 2.4.5.10.6. shmem_chk_ok Function
2.4.5.11. BFM Log and Message Procedures x
2.4.5.11.1. ebfm_display Verilog HDL Function 2.4.5.11.2. ebfm_log_stop_sim Verilog HDL Function 2.4.5.11.3. ebfm_log_set_suppressed_msg_mask Task 2.4.5.11.4. ebfm_log_set_stop_on_msg_mask Verilog HDL Task 2.4.5.11.5. ebfm_log_open Verilog HDL Function 2.4.5.11.6. ebfm_log_close Verilog HDL Function
2.4.5.12. Verilog HDL Formatting Functions x
2.4.5.12.1. himage1 2.4.5.12.2. himage2 2.4.5.12.3. himage4 2.4.5.12.4. himage8 2.4.5.12.5. himage16 2.4.5.12.6. dimage1 2.4.5.12.7. dimage2 2.4.5.12.8. dimage3 2.4.5.12.9. dimage4 2.4.5.12.10. dimage5 2.4.5.12.11. dimage6 2.4.5.12.12. dimage7
1. Design Example Description
2. Quick Start Guide
3. R-Tile Avalon® Streaming Intel® FPGA IP for PCI Express* Design Example User Guide Archives
4. Document Revision History for the R-tile Avalon® Streaming Intel FPGA IP for PCI Express Design Example User Guide

1.1. Credit Initialization Sequence

In R-tile, the back-pressure mechanism by the PIO component is done through the credit system. Therefore, the credit value must be declared during the credit initialization stage. An initial TX credit value is captured by the DUT and will be deducted for any TLP sent to the PIO. When the credit value reaches zero, the DUT stops sending any more TLP until the credit is returned by the PIO.

For the R-tile design example, the RX_CRDT_INIT block interfaces with the credit signals from the DUT as shown in the figure below. The block focuses on initializing and returning the RX credit. In the TX direction, only crdt_init_ack is asserted in the block to complete the initialization stage. The PIO component will capture the TX credit during the initialization stage, which is initiated by the DUT.

Figure 6. Credit System of the Design Example

The waveforms below show the initialization sequence for RX credit from PIO to DUT. During the initialization phase, the *crdt_init signal is asserted by the PIO. In response, the DUT will assert the *crdt_init_ack. After receiving the ack signal, the *crdt_update is asserted and the *crdt_update_cnt value is captured by the internal crdt_cnt by the DUT

Figure 7. Waveforms of Credit Transactions During the Initialization Stage
Level Two Title