MAC Receiver

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MAC receiver block receives data using MII, GMII, or SGMII interface and stores the data in the RX packet buffer. Using RX DMA controller, data from the RX packet buffer is read and transferred to the memory using AXI interface.

The MAC receive block checks for valid preamble, FCS, alignment, and length, and presents received frames to the MAC address checking block. Firmware can configure GEM to receive jumbo frames up to 10,240 bytes.

The address checker identifies the following:

During frame reception, if the frame is too long, a bad frame indication is sent to the DMA controller and the receiver logic does not store that frame in the internal DMA buffer. At the end of frame reception, the receive block indicates to the DMA block whether the frame is good or bad. The DMA block recovers the current receive buffer if the frame is bad.