autoneg_enable - 3.1 English

UltraScale+ Devices Integrated 100G Ethernet Subsystem Product Guide (PG203)

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3.1 English

When the ctl_autoneg_enable input signal is set to 1, auto negotiation begins automatically at power-up, or if the carrier signal is lost, or if the input ctl_restart_negotiation signal is cycled from a 0 to a 1. All of the Ability input signals as well as the two input signals pause and asm_dir are tied Low or High to indicate the capability of the hardware. The nonce_seed[7:0] input must be set to a unique non-zero value for every instance of the auto negotiator. This is important to guarantee that no dead-locks occur at power-up. If two link partners connected together attempt to auto-negotiate with their nonce_seed[7:0] inputs set to the same value, the auto-negotiation fails continuously. The ctl_an_pseudo_sel input is an arbitrary selection that is used to select the polynomial of the random bit generator used in bit position 49 of the DME pages used during auto-negotiation. Any selection on this input is valid and does not result in any adverse behavior.