DMA FIFO - 2022.2 English

AI Engine Kernel and Graph Programming Guide (UG1079)

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2022.2 English

A fifo_depth() constraint specification above 40 allocates FIFOs from memory, known as DMA FIFOs. The following is an example of a FIFO allocation for a request of fifo_depth(3000) bytes which is allocated in memory.

Figure 1. DMA FIFO Allocation

Note: TLAST is dropped when data goes through DMA FIFO.
Note: Write to DMA FIFO must be continuous or multiple of 4 words (4 words = 128 bits).

You can also specify the type of FIFO allocated, whether stream switch or DMA, as well as their locations. More information can be found in FIFO Location Constraints.