Embedded Peripherals IP User Guide

ID 683130
Date 8/11/2025
Public
Document Table of Contents
1. Introduction 2. Avalon® -ST Single-Clock and Dual-Clock FIFO Cores 3. Avalon® -ST Serial Peripheral Interface Core 4. SPI Core 5. SPI Agent/JTAG to Avalon® Host Bridge Cores 6. Intel eSPI Agent Core 7. eSPI to LPC Bridge Core 8. Ethernet MDIO Core 9. Intel FPGA 16550 Compatible UART Core 10. UART Core 11. JTAG UART Core 12. Intel FPGA Avalon® Mailbox Core 13. Intel FPGA Avalon® Mutex Core 14. Intel FPGA Avalon® I2C (Host) Core 15. Intel FPGA I2C Agent to Avalon® -MM Host Bridge Core 16. Intel FPGA Avalon® Compact Flash Core 17. EPCS/EPCQA Serial Flash Controller Core 18. Intel FPGA Serial Flash Controller Core 19. Intel FPGA Serial Flash Controller II Core 20. Intel FPGA Generic QUAD SPI Controller Core 21. Intel FPGA Generic QUAD SPI Controller II Core 22. Interval Timer Core 23. Intel FPGA Avalon FIFO Memory Core 24. On-Chip Memory (RAM and ROM) Intel FPGA IP 25. On-Chip Memory II (RAM or ROM) Intel FPGA IP 26. Optrex 16207 LCD Controller Core 27. PIO Core 28. PLL Cores 29. DMA Controller Core 30. Modular Scatter-Gather DMA Core 31. Scatter-Gather DMA Controller Core 32. SDRAM Controller Core 33. Tri-State SDRAM Core 34. Video Sync Generator and Pixel Converter Cores 35. Intel FPGA Interrupt Latency Counter Core 36. Performance Counter Unit Core 37. Vectored Interrupt Controller Core 38. Avalon® -ST Data Pattern Generator and Checker Cores 39. Avalon® -ST Test Pattern Generator and Checker Cores 40. System ID Peripheral Core 41. Avalon® Packets to Transactions Converter Core 42. Avalon® -ST Multiplexer and Demultiplexer Cores 43. Avalon® -ST Bytes to Packets and Packets to Bytes Converter IP 44. Avalon® -ST Delay Core 45. Avalon® -ST Round Robin Scheduler Core 46. Avalon® -ST Splitter Core 47. Avalon® -MM DDR Memory Half Rate Bridge Core 48. Intel FPGA GMII to RGMII Converter Core 49. HPS GMII to RGMII Adapter Intel® FPGA IP 50. Intel FPGA MII to RMII Converter Core 51. HPS GMII to TSE 1000BASE-X/SGMII PCS Bridge Core Intel® FPGA IP 52. Intel FPGA HPS EMAC to Multi-rate PHY GMII Adapter Core 53. Intel FPGA MSI to GIC Generator Core 54. Cache Coherency Translator Intel® FPGA IP 55. Altera ACE5-Lite Cache Coherency Translator 56. Lightweight UART Core

47.3. Functional Description

The Avalon® MM DDR Memory Half Rate Bridge works under two constraints:

  • Its memory-side host has a clock frequency that is synchronous (zero phase shift) to, and twice the frequency of, the CPU-side agent.
  • Its memory-side host is half as wide as its CPU-side agent.

The bridge leverages these two constraints to provide lightweight, low-latency clock-crossing logic between the CPU and the memory. These constraints are in contrast with the Avalon® -MM Clock-Crossing Bridge, which makes no assumptions about the frequency/phase relationship between the host- and agent-side clocks, and provides higher-latency logic that fully-synchronizes all signals that pass between the two domains.

The Avalon® MM DDR Memory Half-Rate Bridge has an Avalon® -MM agent interface that accepts single-word (non-bursting) transactions. When the agent interface receives a transaction from a connected CPU, it issues a two-word burst transaction on its host interface (which is half as wide and twice as fast). If the transaction is a read request, the bridge's host interface waits for the agent’s two-word response, concatenates the two words, and presents them as a single readdata word on its agent interface to the CPU. Every time the data width is halved, the clock rate is doubled. As a result, the data throughput is matched between the CPU and the off-chip memory device.

The figure below shows the latency in the Avalon® -MM Half-Rate Bridge core. The core adds two cycles of latency in the agent clock domain for read transactions. The first cycle is introduced during the command phase of the transaction and the second cycle, during the response phase of the transaction. The total latency is 2+<x>, where <x> refers to the latency of the DDR SDRAM high-performance memory controller. Using the clock crossing bridge for this same purpose would impose approximately 12 cycles of additional latency.

Figure 160.  Avalon® -MM DDR Memory Half-Rate Bridge Block Diagram