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

31.7. IP Caveats

There are limitations in the Intel FPGA interrupt latency which the user needs to be aware of. This limitation arises due to the nature of state machines which incurs a period of clock cycle for state transitions.
  1. The data latency registers cannot be read before a first IRQ is fired in any of the 32 channels. This causes the Waitrequest signal to be perpetually high which would lead to a system stall.
  2. The data registers can only be read three clock cycles after the counter registers stop counting. These three clock cycles originate from the state machine moving from the start state to the stop/store state. It takes an additional clock cycle to propagate the data from the counter registers to the data store registers.
  3. In the pulse IRQ mode, there is an idle cycle present between two consecutive write commands into the counter stop register. So, in the event that channel 1 is halted immediately after channel 0 is halted, then the minimum difference you see in the registered values is 2.
  4. The interrupt latency counter will not notify you if an overflow occurs but the counter can count up to very huge numbers before an overflow happens. The magnitude of the delay numbers reported will suggest that the system has hung indefinitely.