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

15.2.5. Write Operation

The Avalon® write data width is 32 bits wide. A 32-bit width limits the bridge to only issue word align Avalon® addresses. It also allows the upstream I2C host to write to any sequence of bytes on any address alignment. There is a conversion logic which sits between the Avalon® interface and the I2C interface.

Write operation conversion logic flow:

  • Checks the address alignment issued by the I2C host.
  • Enables data by setting byteenable high to indicate which byte address the I2C host wants to write into.
    Note: If the address issued by I2C host is 0x03h, the byteenable is 4’b1000.
  • Combines multiple bytes of data into a 32-bit packet if their addresses are sequential.
    Note: If the first write is to address 0x04 and the second write is to address 0x05, then byteenable is 4’b0011.

Legal byteenable combinations are 4’b0001, 4’b0010, 4’b0100, 4’b1000, 4’b0011, 4’b1100 and 4’b1111.

  • If the write request issued by the I2C host ends up with an illegal byteenable combination such as, 4’b0110, 4’b0111, or 4’b1110, then the bridge generates multiple Avalon® byte writes.
    Note: If the sequential write request from the I2C host starts from 0x0 and ends at 0x02 (illegal byteenable, b’0111), then the bridge will generate three Avalon® write requests with legal byteenable 4’b0001, 4’b0010 and 4’b0100.
  • Issues a word align Avalon® address according to the address sent by the I2C host with the two LSB set to zero.

Upon receiving of the agent address with the R/W bit set to zero, the bridge issues an acknowledge to the I2C host. The next byte transmitted by the host is the byte address. The byte address is written into the address counter inside the bridge. The bridge acknowledges the I2C host again and the host transmits the data byte to be written into the addressed memory location. The host keeps sending data bytes to the bridge and terminates the operation with a Stop condition at the end.

Figure 60. Write Operation