Embedded Peripherals IP User Guide

ID 683130
Date 9/18/2024
Public
Document Table of Contents
1. Introduction 2. Avalon® -ST Multi-Channel Shared Memory FIFO Core 3. Avalon® -ST Single-Clock and Dual-Clock FIFO Cores 4. Avalon® -ST Serial Peripheral Interface Core 5. SPI Core 6. SPI Agent/JTAG to Avalon® Host Bridge Cores 7. Intel eSPI Agent Core 8. eSPI to LPC Bridge Core 9. Ethernet MDIO Core 10. Intel FPGA 16550 Compatible UART Core 11. UART Core 12. JTAG UART Core 13. Intel FPGA Avalon® Mailbox Core 14. Intel FPGA Avalon® Mutex Core 15. Intel FPGA Avalon® I2C (Host) Core 16. Intel FPGA I2C Agent to Avalon® -MM Host Bridge Core 17. Intel FPGA Avalon® Compact Flash Core 18. EPCS/EPCQA Serial Flash Controller Core 19. Intel FPGA Serial Flash Controller Core 20. Intel FPGA Serial Flash Controller II Core 21. Intel FPGA Generic QUAD SPI Controller Core 22. Intel FPGA Generic QUAD SPI Controller II Core 23. Interval Timer Core 24. Intel FPGA Avalon FIFO Memory Core 25. On-Chip Memory (RAM and ROM) Intel FPGA IP 26. On-Chip Memory II (RAM or ROM) Intel FPGA IP 27. Optrex 16207 LCD Controller Core 28. PIO Core 29. PLL Cores 30. DMA Controller Core 31. Modular Scatter-Gather DMA Core 32. Scatter-Gather DMA Controller Core 33. SDRAM Controller Core 34. Tri-State SDRAM Core 35. Video Sync Generator and Pixel Converter Cores 36. Intel FPGA Interrupt Latency Counter Core 37. Performance Counter Unit Core 38. Vectored Interrupt Controller Core 39. Avalon® -ST Data Pattern Generator and Checker Cores 40. Avalon® -ST Test Pattern Generator and Checker Cores 41. System ID Peripheral Core 42. Avalon® Packets to Transactions Converter Core 43. Avalon® -ST Multiplexer and Demultiplexer Cores 44. Avalon® -ST Bytes to Packets and Packets to Bytes Converter Cores 45. Avalon® -ST Delay Core 46. Avalon® -ST Round Robin Scheduler Core 47. Avalon® -ST Splitter Core 48. Avalon® -MM DDR Memory Half Rate Bridge Core 49. Intel FPGA GMII to RGMII Converter Core 50. HPS GMII to RGMII Adapter Intel® FPGA IP 51. Intel FPGA MII to RMII Converter Core 52. HPS GMII to TSE 1000BASE-X/SGMII PCS Bridge Core Intel® FPGA IP 53. Intel FPGA HPS EMAC to Multi-rate PHY GMII Adapter Core 54. Intel FPGA MSI to GIC Generator Core 55. Cache Coherency Translator Intel® FPGA IP 56. Lightweight UART Core

10.4.7. lsr

Identifier Title Offset Access Reset Value Description
lsr Line Status Register 0x14 R 0x00000060 Reports status of transmit and receive.
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
rfe temt thre bi fe pe oe dr
Table 85.  lsr Fields
Bit Name/ Identifier Description Access Reset
[31:8] Reserved R 0x0
[7] Receiver FIFO Error bit (rfe)

This bit is only relevant when FIFO's are enabled (FCR[0] set to one). This is used to indicate if there is at least one parity error, framing error, or break indication in the FIFO. This bit is cleared when the LSR is read and the character with the error is at the top of the receiver FIFO and there are no subsequent errors in the FIFO.

R 0x0
[6] Transmitter Empty bit (temt)

If in FIFO mode and FIFO's enabled (FCR[0] set to one), this bit is set whenever the Transmitter Shift Register and the FIFO are both empty. If FIFO's are disabled, this bit is set whenever the Transmitter Holding Register and the Transmitter Shift Register are both empty. Indicator is cleared when new data is written into the THR or Transmit FIFO.

R 0x1
[5] Transmit Holding Register Empty bit (thre)

This bit indicates that the THR or Tx FIFO is empty. This bit is set when data is transferred from the THR or Tx FIFO to the transmitter shift register and no new data has been written to the THR or Tx FIFO. This also causes a THRE Interrupt to execute, if the THRE Interrupt is enabled.

R 0x1
[4] Break Interrupt (bi)

This is used to indicate the detection of a break sequence on the serial input data. Set whenever the serial input, sin, is held in a logic 0 state for longer than the sum of start time + data bits + parity + stop bits. A break condition on serial input causes one and only one character, consisting of all zeros, to be received by the UART. The character associated with the break condition is carried through the FIFO and is revealed when the character is at the top of the FIFO. This bit always stays in sync with the associated character in RBR. If the current associated character is read through RBR, this bit will be updated to be in sync with the next character in RBR. Reading the LSR clears the BI bit.

RC 0x0
[3] Framing Error (fe)

This is used to indicate the occurrence of a framing error in the receiver. A framing error occurs when the receiver does not detect a valid STOP bit in the received data. In the FIFO mode, since the framing error is associated with a character received, it is revealed when the character with the framing error is at the top of the FIFO. When a framing error occurs the UART will try to resynchronize. It does this by assuming that the error was due to the start bit of the next character and then continues receiving the other bit data, and/or parity and stop. It should be noted that the Framing Error (FE) bit(LSR[3]) will be set if a break interrupt has occurred, as indicated by a Break Interrupt BIT bit (LSR[4]). This bit always stays in sync with the associated character in RBR. If the current associated character is read through RBR, this bit will be updated to be in sync with the next character in RBR. Reading the LSR clears the FE bit.

RC 0x0
[2] Parity Error (pe)

This is used to indicate the occurrence of a parity error in the receiver if the Parity Enable (PEN) bit (LCR[3]) is set. Since the parity error is associated with a character received, it is revealed when the character with the parity error arrives at the top of the FIFO. It should be noted that the Parity Error (PE) bit (LSR[2]) will be set if a break interrupt has occurred, as indicated by Break Interrupt (BI) bit (LSR[4]). In this situation, the Parity Error bit is set depending on the combination of EPS (LCR[4]) and DLS (LCR[1:0]). This bit always stays in sync with the associated character in RBR. If the current associated character is read through RBR, this bit will be updated to be in sync with the next character in RBR. Reading the LSR clears the PE bit.

RC 0x0
[1] Overrun error bit (oe)

This is used to indicate the occurrence of an overrun error. This occurs if a new data character was received before the previous data was read. In the non-FIFO mode, the OE bit is set when a new character arrives in the receiver before the previous character was read from the RBR. When this happens, the data in the RBR is overwritten. In the FIFO mode, an overrun error occurs when the FIFO is full and new character arrives at the receiver. The data in the FIFO is retained and the data in the receive shift register is lost.Reading the LSR clears the OE bit.

RC 0x0
[0] Data Ready bit (dr)

This is used to indicate that the receiver contains at least one character in the RBR or the receiver FIFO. This bit is cleared when the RBR is read in the non-FIFO mode, or when the receiver FIFO is empty, in the FIFO mode.

R 0x0