The RX interface is the gateway to the RX datapath of the GTM transceiver. The application receives data through the GTM transceiver by reading data to the RXDATA port on the positive edge of RXUSRCLK. Port widths can be 32, 40, 64, 80, 128, 160, and 256 bits for NRZ mode, or 64, 80, 128, 160, 256, 320, and 512 bits for PAM4 mode. The rate of the parallel clock (RXUSRCLK) at the interface is determined by the RX line rate and the width of the RXDATA port.
Each RX fabric interface natively supports up to 256 bits output to the fabric design. To extend fabric interface support to 320 and 512 bits, two RX channel interfaces should be combined—this is referred to as half density mode. In this mode, only one RX front end channel is active. Refer to RX Interface Width Configuration for more details.