Generally, there are two methods to transfer data between kernels–window or stream. When using the window, data transfers can be realized as ping-pong buffers or optionally, using a single buffer. AI Engine tools will take care of buffer synchronization between the kernels. Designers need to decide the window size and buffer location between kernels through their partition of the application. If an overlap is needed between different windows of the data, AI Engine tools provide options for setting a margin for the window, that is, to copy the overlap of data by AI Engine tools automatically.
When using the stream, the data movement involves two input as well as two output stream ports, along with one dedicated cascade stream input port and output port. Stream ports can provide 32-bit per cycle or, 128-bit per four cycles on each port. Stream interfaces are bidirectional and can read or write neighboring or non-neighboring AI Engines by stream ports. However, cascade stream ports are unidirectional and only provide a one-way access between the neighboring AI Engines.