Embedded Peripherals IP User Guide

ID 683130
Date 10/24/2025
Public
Document Table of Contents
1. Introduction 2. Avalon® -ST Serial Peripheral Interface Core 3. SPI Core 4. SPI Agent/JTAG to Avalon® Host Bridge Cores 5. Intel eSPI Agent Core 6. eSPI to LPC Bridge Core 7. Ethernet MDIO Core 8. Intel FPGA 16550 Compatible UART Core 9. UART Core 10. Lightweight 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. EPCS/EPCQA Serial Flash Controller Core 17. Intel FPGA Serial Flash Controller Core 18. Intel FPGA Serial Flash Controller II Core 19. Intel FPGA Generic QUAD SPI Controller Core 20. Intel FPGA Generic QUAD SPI Controller II Core 21. Interval Timer Core 22. Intel FPGA Avalon FIFO Memory Core 23. On-Chip Memory (RAM and ROM) Intel FPGA IP 24. On-Chip Memory II (RAM or ROM) Intel FPGA IP 25. PIO Core 26. PLL Cores 27. DMA Controller Core 28. Modular Scatter-Gather DMA Core 29. Scatter-Gather DMA Controller Core 30. Video Sync Generator and Pixel Converter Cores 31. Intel FPGA Interrupt Latency Counter Core 32. Performance Counter Unit Core 33. Vectored Interrupt Controller Core 34. System ID Peripheral Core 35. Intel FPGA GMII to RGMII Converter Core 36. HPS GMII to RGMII Adapter IP 37. Intel FPGA MII to RMII Converter Core 38. HPS GMII to TSE 1000BASE-X/SGMII PCS Bridge Core IP 39. Intel FPGA HPS EMAC to Multi-rate PHY GMII Adapter Core 40. Intel FPGA MSI to GIC Generator Core 41. Cache Coherency Translator IP 42. Altera ACE5-Lite Cache Coherency Translator

38.3.4. Transmit Elastic Buffer

Transmit elastic buffer is asynchronous FIFO with fix high and low watermark level. High watermark level is fixed at (TX_BUFFER_DEPTH/2 + 4) valid entries and low watermark level is fixed at (TX_BUFFER_DEPTH/2 - 4) valid entries. When the number of valid entries is equal or above the high watermark level, any IDLE symbol appearing at the write port of the buffer is dropped (IDLE symbol deletion). When the number of valid entries is equal or below low watermarks level, any IDLE symbol read from the read port does not increment the read pointer of the buffer (IDLE symbol insertion). IDLE symbol definition is tx_en = 0 and tx_err = 0.

The buffer depth is fixed at 64. Higher buffer depths provides more margins to avoid overflow/underflow condition to occur. The buffer depth configuration depends on the maximum Ethernet packet or maximum IDLE symbol separation in the Ethernet protocol and the maximum ppm different between the two clock sources.

Figure 166. Elastic Buffer Watermark Level