Specifications

Software Developer’s Manual 177
Ethernet Interface
When the XOFF signal is asserted high, the device transmits a single XOFF frame. The assertion of
I_XON (after deassertion of XOFF) initiates an XON frame transmission if enabled by
FCRTL.XONE. The assertion/deassertion of XON is required between assertions of XOFF in order
to send another XOFF frame, providing a built-in hysteresis mechanism.
Output signals are also provided from the
82544GC/EI to indicate the device is either above the
programmed flow control high threshold or below the flow control low threshold (ABV_HI and
BLW_LOW respectively).
Flow control transmission must also be enabled through CTRL.TFCE.