Embedded Peripherals IP User Guide

ID 683130
Date 8/11/2025
Public
Document Table of Contents
1. Introduction 2. Avalon® -ST Single-Clock and Dual-Clock FIFO Cores 3. Avalon® -ST Serial Peripheral Interface Core 4. SPI Core 5. SPI Agent/JTAG to Avalon® Host Bridge Cores 6. Intel eSPI Agent Core 7. eSPI to LPC Bridge Core 8. Ethernet MDIO Core 9. Intel FPGA 16550 Compatible UART Core 10. 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. Intel FPGA Avalon® Compact Flash Core 17. EPCS/EPCQA Serial Flash Controller Core 18. Intel FPGA Serial Flash Controller Core 19. Intel FPGA Serial Flash Controller II Core 20. Intel FPGA Generic QUAD SPI Controller Core 21. Intel FPGA Generic QUAD SPI Controller II Core 22. Interval Timer Core 23. Intel FPGA Avalon FIFO Memory Core 24. On-Chip Memory (RAM and ROM) Intel FPGA IP 25. On-Chip Memory II (RAM or ROM) Intel FPGA IP 26. Optrex 16207 LCD Controller Core 27. PIO Core 28. PLL Cores 29. DMA Controller Core 30. Modular Scatter-Gather DMA Core 31. Scatter-Gather DMA Controller Core 32. SDRAM Controller Core 33. Tri-State SDRAM Core 34. Video Sync Generator and Pixel Converter Cores 35. Intel FPGA Interrupt Latency Counter Core 36. Performance Counter Unit Core 37. Vectored Interrupt Controller Core 38. Avalon® -ST Data Pattern Generator and Checker Cores 39. Avalon® -ST Test Pattern Generator and Checker Cores 40. System ID Peripheral Core 41. Avalon® Packets to Transactions Converter Core 42. Avalon® -ST Multiplexer and Demultiplexer Cores 43. Avalon® -ST Bytes to Packets and Packets to Bytes Converter IP 44. Avalon® -ST Delay Core 45. Avalon® -ST Round Robin Scheduler Core 46. Avalon® -ST Splitter Core 47. Avalon® -MM DDR Memory Half Rate Bridge Core 48. Intel FPGA GMII to RGMII Converter Core 49. HPS GMII to RGMII Adapter Intel® FPGA IP 50. Intel FPGA MII to RMII Converter Core 51. HPS GMII to TSE 1000BASE-X/SGMII PCS Bridge Core Intel® FPGA IP 52. Intel FPGA HPS EMAC to Multi-rate PHY GMII Adapter Core 53. Intel FPGA MSI to GIC Generator Core 54. Cache Coherency Translator Intel® FPGA IP 55. Altera ACE5-Lite Cache Coherency Translator 56. Lightweight UART Core

9.4.1. rbr_thr_dll

Identifier Title Offset Access Reset Value Description
rbr_thr_dll Rx Buffer, Tx Holding, and Divisor Latch Low 0x0 RW 0x0000000 This is a multi-function register. This register holds receives and transmit data and controls the least-signficant 8 bits of the baud rate divisor.
Note: Rx Buffer register and Tx Holding register use 9-bit. The divisor latch low uses 8-bit only.
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
  rbr_thr_dll
Table 71.  rbr_thr_dll Fields
Bit Name/Identifier Description Access Reset
[31:8] Reserved R 0x0
[7:0] rbr_thr_dll
  • Receive Buffer Register:

    This register contains the data byte received on the serial input port (sin). The data in this register is valid only if the Data Ready (LSR[0] is set to 1). If FIFOs are disabled (FCR[0] is cleared to 0) the data in the RBR must be read before the next data arrives, otherwise it will be overwritten, resulting in an overrun error. If FIFOs are enabled (FCR[0] set to 1) this register accesses the head of the receive FIFO. If the receive FIFO is full, and this register is not read before the next data character arrives, then the data already in the FIFO will be preserved but any incoming data will be lost. An overrun error will also occur.

  • Transmit Holding Register:

    This register contains data to be transmitted on the serial output port (sout). Data should only be written to the THR when the THR Empty bit (LSR[5] is set to 1). If FIFOs are disabled (FCR[0] is set to 0) and THRE is set to 1, writing a single character to the THR clears the THRE. Any additional writes to the THR before the THRE is set again causes the THR data to be overwritten. If FIFO's are enabled (FCR[0] is set to 1) and THRE is set, the FIFO can be filled up to a pre-configured depth (FIFO_DEPTH). Any attempt to write data when the FIFO is full results in the write data being lost.

  • Divisor Latch Low:

    This register makes up the lower 8-bits of a 16-bit, Read/write, Divisor Latch register that contains the baud rate divisor for the UART. This register may only be accessed when the DLAB bit (LCR[7] is set to 1). 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.
RW 0x00