Embedded Peripherals IP User Guide

ID 683130
Date 3/28/2022
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 54. Cache Coherency Translator Intel® FPGA IP

10.2.11. Hardware Auto Flow-Control

Hardware based auto flow-control uses 2 signals (cts_n & rts_n) from the Modem Control/Status group. With Hardware auto flow-control disabled, these signals will directly drive the Modem Status register (cts_n) or be driven by the Modem Control register (rts_n).

With auto flow-control enabled, these signals perform flow-control duty with another UART at the other end.

The cts_n input is, when active (low state), will allow the Tx FIFO to send data to the transmit buffer. When cts_n is inactive (high state), the Tx FIFO stops sending data to the transmit buffer. cts_n is expected to be connected to the rts_n output of the other UART.

The rts_n output will go active (low state), when the Rx FIFO is empty, signaling to the opposite UART that it is ready for data. The rts_n output goes inactive (high state) when the Rx FIFO level is reached, signaling to the opposite UART that the FIFO is about to go full and it should stop transmitting.

Due to the delays within the UART logic, one additional character may be transmitted after cts_n is sampled active low. For the same reason, the Rx FIFO will accommodate up to 1 additional character after asserting rts_n (this is allowed because Rx FIFO trigger level is at worst, two entries from being truly full). Both are observed to prevent overflow/underflow between UARTs.

Figure 37. Hardware Auto Flow-Control Between two UARTs