Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

5.13.6.7.4. Receive FIFO Overflow

During UART serial transfers, receive FIFO requests are made to the DMA whenever the number of entries in the receive FIFO is at or above the decoded level of Receive Trigger (RT) field in the FIFO Control Register (IIR_FCR). This is known as the watermark level. The DMA responds by fetching a burst of data from the receive FIFO.

Data should be fetched by the DMA often enough for the receive FIFO to accept serial transfers continuously, that is, when the FIFO begins to fill, another DMA transfer is requested. Otherwise, the FIFO fills with data (overflow). To prevent this condition, the user must set the watermark level correctly.