Embedded Memory User Guide: Agilex™ 5 FPGAs and SoCs

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ID 813901
Date 4/01/2024
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Document Table of Contents
Document Table of Contents x
1. Agilex™ 5 Embedded Memory Overview 2. Agilex™ 5 Embedded Memory Architecture and Features 3. Agilex™ 5 Embedded Memory Design Considerations 4. Agilex™ 5 Embedded Memory IP References 5. Agilex™ 5 Embedded Memory Debugging 6. Document Revision History for the Embedded Memory User Guide: Agilex™ 5 FPGAs and SoCs
1. Agilex™ 5 Embedded Memory Overview x
1.1. Agilex™ 5 Embedded Memory Features
2. Agilex™ 5 Embedded Memory Architecture and Features x
2.1. Byte Enable in Agilex™ 5 Embedded Memory Blocks 2.2. Address Clock Enable Support 2.3. Asynchronous Clear and Synchronous Clear 2.4. Memory Blocks Error Correction Code (ECC) Support 2.5. Agilex™ 5 Embedded Memory Clocking Modes 2.6. Agilex™ 5 Embedded Memory Configurations 2.7. Force-to-Zero 2.8. Coherent Read Memory 2.9. Freeze Logic 2.10. True Dual Port Dual Clock Emulator 2.11. Initial Value of Read and Write Address Registers 2.12. Timing/Power Optimization Feature in M20K Blocks
2.1. Byte Enable in Agilex™ 5 Embedded Memory Blocks x
2.1.1. Byte Enable Controls 2.1.2. Data Byte Output 2.1.3. Byte Enable Behavior
2.4. Memory Blocks Error Correction Code (ECC) Support x
2.4.1. Parity Bit 2.4.2. ECC Parity Flip 2.4.3. ECC Read-During-Write Behavior 2.4.4. Error Correction Code Truth Table
2.5. Agilex™ 5 Embedded Memory Clocking Modes x
2.5.1. Single Clock Mode 2.5.2. Read/Write Clock Mode 2.5.3. Input/Output Clock Mode 2.5.4. Asynchronous/Synchronous Clears in Clocking Modes 2.5.5. Output Read Data in Simultaneous Read/Write 2.5.6. Independent Clock Enables in Clocking Modes
2.6. Agilex™ 5 Embedded Memory Configurations x
2.6.1. Mixed-Width Port Configurations
2.8. Coherent Read Memory x
2.8.1. Forwarding Logic
3. Agilex™ 5 Embedded Memory Design Considerations x
3.1. Consider the Memory Block Selection 3.2. Consider the Concurrent Read Behavior 3.3. Customize Read-During-Write Behavior 3.4. Consider Power-Up State and Memory Initialization 3.5. Reduce Power Consumption 3.6. Avoid Providing Non-Deterministic Input 3.7. Avoid Changing Clock Signals and Other Control Signals Simultaneously 3.8. Advanced Settings in Quartus® Prime Software for Memory 3.9. Consider the Memory Depth Setting 3.10. Consider Registering the Memory Output
3.3. Customize Read-During-Write Behavior x
3.3.1. Same-Port Read-During-Write Mode 3.3.2. Mixed-Port Read-During-Write Mode
4. Agilex™ 5 Embedded Memory IP References x
4.1. On Chip Memory RAM and ROM Intel® FPGA IP Cores 4.2. FIFO Intel® FPGA IP 4.3. Shift Register (RAM-based) Intel® FPGA IP
4.1. On Chip Memory RAM and ROM Intel® FPGA IP Cores x
4.1.1. Release Information for RAM and ROM Intel® FPGA IPs 4.1.2. RAM: 1-PORT Intel® FPGA IP Parameters 4.1.3. RAM: 2-PORT Intel® FPGA IP Parameters 4.1.4. RAM: 4-PORT Intel® FPGA IP Parameters 4.1.5. ROM: 1-PORT Intel® FPGA IP Parameters 4.1.6. ROM: 2-PORT Intel® FPGA IP Parameters 4.1.7. Changing Parameter Settings Manually 4.1.8. RAM and ROM Interface Signals
4.1.7. Changing Parameter Settings Manually x
4.1.7.1. RAM and ROM Parameter Settings
4.2. FIFO Intel® FPGA IP x
4.2.1. Release Information for FIFO Intel® FPGA IP 4.2.2. Configuration Methods 4.2.3. Specifications 4.2.4. FIFO Functional Timing Requirements 4.2.5. SCFIFO ALMOST_EMPTY Functional Timing 4.2.6. FIFO Output Status Flag and Latency 4.2.7. FIFO Metastability Protection and Related Options 4.2.8. FIFO Synchronous Clear and Asynchronous Clear Effect 4.2.9. SCFIFO and DCFIFO Show-Ahead Mode 4.2.10. Different Input and Output Width 4.2.11. DCFIFO Timing Constraint Setting 4.2.12. Coding Example for Manual Instantiation 4.2.13. Instantiation Template 4.2.14. Design Example 4.2.15. Gray-Code Counter Transfer at the Clock Domain Crossing 4.2.16. Guidelines for Embedded Memory ECC Feature 4.2.17. FIFO Intel® FPGA IP Parameters 4.2.18. Reset Scheme
4.2.3. Specifications x
4.2.3.1. Verilog HDL Prototype 4.2.3.2. VHDL Component Declaration 4.2.3.3. VHDL LIBRARY-USE Declaration 4.2.3.4. HDL Code from Parameterizable Macros Template 4.2.3.5. FIFO Signals 4.2.3.6. FIFO Parameter Settings
4.2.8. FIFO Synchronous Clear and Asynchronous Clear Effect x
4.2.8.1. Recovery and Removal Timing Violation Warnings when Compiling a DCFIFO
4.2.11. DCFIFO Timing Constraint Setting x
4.2.11.1. Embedded Timing Constraint 4.2.11.2. User Configurable Timing Constraint
4.2.11.2. User Configurable Timing Constraint x
4.2.11.2.1. SDC Commands
4.3. Shift Register (RAM-based) Intel® FPGA IP x
4.3.1. Release Information for Shift Register (RAM-based) Intel® FPGA IP 4.3.2. Shift Register (RAM-based) Intel® FPGA IP Features 4.3.3. Shift Register (RAM-based) Intel® FPGA IP General Description 4.3.4. Shift Register (RAM-based) Intel® FPGA IP Parameter Settings 4.3.5. Shift Register Ports and Parameters Setting
1. Agilex™ 5 Embedded Memory Overview
2. Agilex™ 5 Embedded Memory Architecture and Features
3. Agilex™ 5 Embedded Memory Design Considerations
4. Agilex™ 5 Embedded Memory IP References
5. Agilex™ 5 Embedded Memory Debugging
6. Document Revision History for the Embedded Memory User Guide: Agilex™ 5 FPGAs and SoCs

4.2.5. SCFIFO ALMOST_EMPTY Functional Timing

In SCFIFO, the almost_empty is asserted only when the usedw is less than the almost_empty_value that you set. The almost_empty signal does not consider the data readiness at the output. When the almost_empty_value is set too low, it is possible to observe that SCFIFO asserts the empty signal without asserting the almost_emtpy signal.

Figure 33. Example of empty Signal Assertion without Asserting almost_empty Signal

In this example, the almost_empty_value is 1 which means the almost_empty asserts when usedw is 0. There are three words in the FIFO before the read request is received. After the first read, the wrreq asserts and the rdreq signal remains high. The usedw remains at 2. In the next cycle, the wrreq de-asserts but there is another rdreq going on. The usedw decrease to 1 and the almost_empty signal remains low. However, the write data has not been written into the FIFO due to the write latency. The empty signal asserts to indicate the FIFO is empty.

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