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

8.4.4. fcr

Identifier Title Offset Access Reset Value Description
fcr FIFO Control 0x8 W 0x00000000 Controls FIFO operation when written.
Bit Fields
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
- rt dmam xfifor rfifor fifoe
Table 71.  fcr Fields
Bit Name/Identifier Description Access Reset
[31:8] Reserved R 0x0
[7:6] Rx Trigger Level (rt)

This register is configured to implement FIFOs RxTrigger (or RT). This is used to select the trigger level in the receiver FIFO at which the Received Data Available Interrupt will be generated. In auto flow control mode it is used to determine when the rts_n signal will be de-asserted

The following trigger levels are supported:

  • 00 - One character in FIFO
  • 01 - FIFO 1/4 full
  • 10 - FIFO 1/2 ful
  • 11 - FIFO two less than full
W 0x0
[5:4] Reserved R 0x0
[3] DMA Mode (dmam)

This determines the DMA signaling mode used for the uart_dma_tx_req_n and uart_dma_rx_req_n output signals when additional DMA handshaking signals are not selected. DMA mode 0 supports single DMA data transfers at a time. In mode 0, the uart_dma_tx_req_n signal goes active low under the following conditions:

  • When the Transmitter Holding Register is empty in non-FIFO mode.

  • When the transmitter FIFO is empty in FIFO mode.

It goes inactive under the following conditions:

  • When a single character has been written into the Transmitter Holding Register or transmitter FIFO.

  • When the transmitter FIFO is above the threshold.

DMA mode 1 supports multi-DMA data transfers, where multiple transfers are made continuously until the receiver FIFO has been emptied or the transmit FIFO has been filled. In mode 1 the uart_dma_tx_req_n signal is asserted under the following condition:

  • When the transmitter FIFO is empty.

W 0x0
[2] Tx FIFO Reset (xfifor)

This bit resets the control portion of the transmit FIFO and treats the FIFO as empty. Note that this bit is 'self-clearing' and it is not necessary to clear this bit. Please allow for 8 clock cycles to pass after changing this register bit before reading from RBR or writing to THR.

W 0x0
[1] Rx FIFO Reset (rfifor)

Resets the control portion of the receive FIFO and treats the FIFO as empty. Note that this bit is self-clearing' and it is not necessary to clear this bit. Allow for 8 clock cycles to pass after changing this register bit before reading from RBR or writing to THR.

W 0x0
[0] FIFO Enable (fifoe)

This bit enables/disables the transmit (Tx) and receive (Rx ) FIFO's. Whenever the value of this bit is changed both the Tx and Rx controller portion of FIFO's will be reset.

Any existing data in both Tx and Rx FIFO will be lost when this bit is changed. Please allow for 8 clock cycles to pass after changing this register bit before reading from RBR or writing to THR.

W 0x0