uint32_tfcbba:1;/*This bit initiates a Pause frame in the full-duplex mode and activates the backpressure function in the half-duplex mode if the TFCE bit is set. In the full-duplex mode this bit should be read as 1'b0 before writing to the Flow Control register. To initiate a Pause frame the Application must set this bit to 1'b1. During a transfer of the Control Frame this bit continues to be set to signify that a frame transmission is in progress. After the completion of Pause frame transmission the MAC resets this bit to 1'b0. The Flow Control register should not be written to until this bit is cleared. In the half-duplex mode when this bit is set (and TFCE is set) then backpressure is asserted by the MAC. During backpressure when the MAC receives a new frame the transmitter starts sending a JAM pattern resulting in a collision. When the MAC is configured for the full-duplex mode the BPA(backpressure activate) is automatically disabled.*/