37.8.1 GMAC Network Control Register

Writing a '1' to this bit will flush the next packet from the external RX DPRAM. Flushing the next packet will only take effect if the DMA is not currently writing a packet already stored in the DPRAM to memory.

Takes the values stored in the Transmit PFC Pause Register.

Writing a '1' to this bit enables PFC Priority Based Pause Reception capabilities, enabling PFC negotiation and recognition of priority-based pause frames.

Writing a '1' to this bit causes the CRC of every received frame to be replaced with the value of the nanoseconds field of the 1588 timer that was captured as the receive frame passed the message time stamp point.

Note that bit RFCS in register GMAC_NCFGR may not be set to 1 when the timer should be captured.

Writing a '1' to this bit causes a pause frame with zero quantum to be transmitted.

Writing a '0' to this bit has no effect.

Writing one to this bit causes a pause frame to be transmitted.

Writing a '0' to this bit has no effect.

Writing a '1' to this bit halts transmission as soon as any ongoing frame transmission ends.

Writing a '0' to this bit has no effect.

Writing a '1' to this bit starts transmission.

Writing a '0' to this bit has no effect.

In 10M or 100M half duplex mode, writing a '1' to this bit forces collisions on all received frames. Ignored in gigabit half duplex mode.

Writing a '1' to this bit makes the statistics registers writable for functional test purposes.

Writing a '1' to this bit increments all Statistics Registers by one for test purposes.

Writing a '0' to this bit has no effect.

This bit will always read '0'.

Writing a '1' to this bit clears the Statistics Registers.

Writing a '0' to this bit has no effect.

This bit will always read '0'.

Writing a '1' to this bit enables the Management Port.

Writing a '0' to this bit disables the Management Port, and forces MDIO to high impedance state and MDC to low impedance.

Writing a '1' to this bit enables the GMAC transmitter to send data.

Writing a '0' to this bit stops transmission immediately, the transmit pipeline and control registers is cleared, and the Transmit Queue Pointer Register will be set to point to the start of the transmit descriptor list.

Writing a '1' to this bit enables the GMAC to receive data.

Writing a '0' to this bit stops frame reception immediately, and the receive pipeline is cleared. The Receive Queue Pointer Register is not affected.

Writing '1' to this bit connects GTX to GRX, GTXEN to GRXDV, and forces full duplex mode.

GRXCK and GTXCK may malfunction as the GMAC is switched into and out of internal loop back. It is important that receive and transmit circuits have already been disabled when making the switch into and out of internal loop back.