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

8.4.2. ier_dlh

Identifier Title Offset Access Reset Value Description
ier_dlh Interrupt Enable and Divisor Latch High 0x4 RW 0x00000000

The ier_dlh (Interrupt Enable Register) may only be accessed when the DLAB bit [7] of the LCR Register is set to 0. Allows control of the Interrupt Enables for transmit and receive functions.This is a multi-function register. This register enables/disables receive and transmit interrupts and also controls the most-significant 8-bits of the baud rate divisor.

The Divisor Latch High Register is accessed when the DLAB bit (LCR[7] is set to 1). Bits[7:0] contain the high order 8-bits of the baud rate divisor. The output baud rate is equal to the system clock (clk) frequency divided by sixteen times the value of the baud rate divisor, as follows:

baud rate = (system clock freq) / (16 * divisor)

Note: With the Divisor Latch Registers (DLL and DLH) set to zero, the baud clock is disabled and no serial communications will occur. Also, once the DLL is set, at least 8 system clock cycles should be allowed to pass before transmitting or receiving data.
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
- dlh7_4 edssi_dhl3 elsi_dhl2 etbei_dlh1 erbfi_dlh0
Table 68.  ier_dlh Fields
Bit Name/Identifier Description Access Reset
[31:8] Reserved R 0x0
[7:4] DLH[7:4] (dlh7_4)
  • Divisor Latch High Register:

    Bit 4, 5, 6 and 7 of DLH value.

RW 0x0
[3] DLH[3] and Enable Modem Status Interrupt (edssi_dhl3)
  • Divisor Latch High Register:

    Bit 3 of DLH value.

  • Interrupt Enable Register:

    This is used to enable/disable the generation of Modem Status Interrupts. This is the fourth highest priority interrupt.

RW 0x0
[2] DLH[2] and Enable Receiver Line Status (elsi_dhl2)
  • Divisor Latch High Register:

    Bit 2 of DLH value.

  • Interrupt Enable Register:

    This is used to enable/disable the generation of Receiver Line Status Interrupt. This is the highest priority interrupt

RW 0x0
[1] DLH[1] and Transmit Data Interrupt Control (etbei_dlh1)
  • Divisor Latch High Register:

    Bit 1 of DLH value.

  • Interrupt Enable Register:

    Enable Transmit Holding Register Empty Interrupt. This is used to enable/disable the generation of Transmitter Holding Register Empty Interrupt. This is the third highest priority interrupt.

RW 0x0
[0] DLH[0] and Receive Data Interrupt Enable (erbfi_dlh0)
  • Divisor Latch High Register:

    Bit 0 of DLH value.

  • Interrupt Enable Register:

    This is used to enable/disable the generation of the Receive Data Available Interrupt and the Character Timeout Interrupt (if FIFO's enabled). These are the second highest priority interrupts.

RW 0x0