Embedded Peripherals IP User Guide

ID 683130
Date 12/13/2021
Public

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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. Intel FPGA MII to RMII Converter Core 51. Intel FPGA HPS GMII to TSE 1000BASE-X/SGMII PCS Bridge Core 52. Intel FPGA HPS EMAC to Multi-rate PHY GMII Adapter Core 53. Intel FPGA MSI to GIC Generator Core

11.4.3.3. status Register

The status register consists of individual bits that indicate particular conditions inside the UART core. Each status bit is associated with a corresponding interrupt-enable bit in the control register. The status register can be read at any time. Reading does not change the value of any of the bits. Writing zero to the status register clears the DCTS, E, TOE, ROE, BRK, FE, and PE bits.

Table 97.  status Register Bits
Bit Name Access Description
0 18 PE RC Parity error. A parity error occurs when the received parity bit has an unexpected (incorrect) logic level. The PE bit is set to 1 when the core receives a character with an incorrect parity bit. The PE bit stays set to 1 until it is explicitly cleared by a write to the status register. When the PE bit is set, reading from the rxdata register produces an undefined value.

If the Parity hardware option is not enabled, no parity checking is performed and the PE bit always reads 0. Refer to Data Bits, Stop Bits, Parity section.

1 FE RC Framing error. A framing error occurs when the receiver fails to detect a correct stop bit. The FE bit is set to 1 when the core receives a character with an incorrect stop bit. The FE bit stays set to 1 until it is explicitly cleared by a write to the status register. When the FE bit is set, reading from the rxdata register produces an undefined value.
2 BRK RC Break detect. The receiver logic detects a break when the RXD pin is held low (logic 0) continuously for longer than a full-character time (data bits, plus start, stop, and parity bits). When a break is detected, the BRK bit is set to 1. The BRK bit stays set to 1 until it is explicitly cleared by a write to the status register.
3 ROE RC Receive overrun error. A receive-overrun error occurs when a newly received character is transferred into the rxdata holding register before the previous character is read (in other words, while the RRDY bit is 1). In this case, the ROE bit is set to 1, and the previous contents of rxdata are overwritten with the new character. The ROE bit stays set to 1 until it is explicitly cleared by a write to the status register.
4 TOE RC Transmit overrun error. A transmit-overrun error occurs when a new character is written to the txdata holding register before the previous character is transferred into the shift register (in other words, while the TRDY bit is 0). In this case the TOE bit is set to 1. The TOE bit stays set to 1 until it is explicitly cleared by a write to the status register.
5 TMT R Transmit empty. The TMT bit indicates the transmitter shift register’s current state. When the shift register is in the process of shifting a character out the TXD pin, TMT is set to 0. When the shift register is idle (in other words, a character is not being transmitted) the TMT bit is 1. An Avalon® -MM host peripheral can determine if a transmission is completed (and received at the other end of a serial link) by checking the TMT bit.
6 TRDY R Transmit ready. The TRDY bit indicates the txdata holding register’s current state. When the txdata register is empty, it is ready for a new character, and TRDY is 1. When the txdata register is full, TRDY is 0. An Avalon® -MM host peripheral must wait for TRDY to be 1 before writing new data to txdata.
7 RRDY R Receive character ready. The RRDY bit indicates the rxdata holding register’s current state. When the rxdata register is empty, it is not ready to be read and RRDY is 0. When a newly received value is transferred into the rxdata register, RRDY is set to 1. Reading the rxdata register clears the RRDY bit to 0. An Avalon® -MM host peripheral must wait for RRDY to equal 1 before reading the rxdata register.
8 E RC Exception. The E bit indicates that an exception condition occurred. The E bit is a logical-OR of the TOE, ROE, BRK, FE, and PE bits. The E bit and its corresponding interrupt-enable bit (IE) bit in the control register provide a convenient method to enable/disable IRQs for all error conditions.

The E bit is set to 0 by a write operation to the status register.

10 18 DCTS RC Change in clear to send (CTS) signal. The DCTS bit is set to 1 whenever a logic-level transition is detected on the CTS_N input port (sampled synchronously to the Avalon® -MM clock). This bit is set by both falling and rising transitions on CTS_N. The DCTS bit stays set to 1 until it is explicitly cleared by a write to the status register.
11 18 CTS R Clear-to-send (CTS) signal. The CTS bit reflects the CTS_N input’s instantaneous state (sampled synchronously to the Avalon® -MM clock).

The CTS_N input has no effect on the transmit or receive processes. The only visible effect of the CTS_N input is the state of the CTS and DCTS bits, and an IRQ that can be generated when the control register’s idcts bit is enabled.

12 18 EOP R18 End of packet encountered. The EOP bit is set to 1 by one of the following events:

An EOP character is written to txdata

An EOP character is read from rxdata

The EOP character is determined by the contents of the endofpacket register. The EOP bit stays set to 1 until it is explicitly cleared by a write to the status register.

If the Include End-of-Packet Register hardware option is not enabled, the EOP bit always reads 0. Refer to Streaming Data (DMA) Control Section.

18 This bit is optional and may not exist in hardware.