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

5.1.2. Transaction Layer

The RX Shifter block in the transaction layer gets the parallel data bus from the link layer. The RX Shifter block identifies the fields of an eSPI transaction such as Header, Data, or Status and sends it to the Command Detector block for decoding. On the transmit side, the Response Generator block gathers information about the eSPI transaction. Thereafter, the TX shifter block sends out the transaction as per the field order to the link layer.

The transaction layer also contains an Error Detection and Handling block. There is no error correction capability or hardware recovery mechanism defined for the eSPI bus. The eSPI agent core categorizes and handles the errors detected on the eSPI bus as follows:
Table 12.  Error Detection and Handling Categories
Error Condition eSPI Agent Core Response and Handling
Invalid command opcode Command is discarded. eSPI agent core responds with NO_RESPONSE opcode.
Invalid cycle type Command is discarded. eSPI agent core responds with NO_RESPONSE opcode.
Command phase CRC error Command is discarded. eSPI agent core responds with NO_RESPONSE opcode.
Unexpected espi_cs_n de-assertion eSPI agent core tri-states the data bus after espi_cs_n is deasserted and follows tSHQZ rule. It also triggers CRC error during response phase only if CRC checking is enabled.
Protocol error:
  • PUT without FREE
  • GET without AVAILABLE
Command is discarded. eSPI agent core responds with FATAL_ERROR opcode.
Malformed packet during command phase:
  • Peripheral Channel:
    • Payload length > Maximum Payload Size
    • Read Request Size > Maximum Read Request Size
    • (Address + Length) > 4Kb
  • Virtual Wire Channel:
    • Count > Maximum Virtual Wire Count
Command is discarded. eSPI agent core responds with FATAL_ERROR opcode.
When PORT 00h to PORT 100h only supports PC_CHANNEL IO SHORT command and the host issues IO READ/WRITE SHORT command to address outside of 00h to 100h. Command is discarded. eSPI agent core responds with NON_FATAL_ERROR opcode.
Besides the Error Detection and Handling block, there is a CRC-8 Generator block to protect the eSPI transaction packets. The command phase and response phase contain their respective CRC byte. For command phase, the CRC calculation includes all the bytes during the command phase such as the Command Opcode, Header and Data. For response phase, the CRC calculation includes all the bytes during the response phase such as the Response Opcode (except WAIT_STATE), Header, Data and Status. CRC checking is disabled by default. To enable CRC checking, set the CRC Checking Enable bit using the SET_CONFIGURATION command.