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

31.6.1. Interrupt Latency Counter Architecture

Interrupt Latency Calculator Architecture

The interrupt latency calculator operates on a single clock domain which is determined by which clock it is receiving at the CLK interface. The interrupt detector circuit is made up of a positive-edge triggered flop which delays the IRQ signal to be XORed with the original signal. The pulse resulted from the previous operation is then fed to an enable register where it will switch its state from logic ‘low’ to ‘high’. This will trigger the counter to start its operation. Prior to this, the reset signal is assumed to be triggered through the firmware. Once the Interrupt service routine has been completed, the IRQ signal drops to logic low. This causes another pulse to be generated to stop the counter. Data from the counter is then duplicated into the latency data register to be read out.

When the interrupt detector is configured to react to a pulse signal, the incoming pulse is fed directly to enable the register to turn on the counter. In this mode, to halt the counter’s operation, you have to write a Boolean ‘1’ to the counter stop bit. Only the first IRQ pulse can trigger the counter to start counting and that subsequent pulse will not cause the counter to reset until a Boolean ‘1’ is written into the counter stop register. In ‘pulse’ mode, the latency measured by the IP is one clock cycle more than actual latency.