Chapter 41 gmac ethernet Interface


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Description

4

RW

0x0

DC
Deferral Check
When this bit is set, the deferral check function is enabled in the GMAC. The GMAC will issue a Frame Abort status, along with the excessive deferral error bit set in the transmit frame status when the transmit state machine is deferred for more than 24,288 bit times in 10/100-Mbps mode. If the Core is configured for 1000 Mbps operation, the threshold for deferral is 155,680 bits times. Deferral begins when the transmitter is ready to transmit, but is prevented because of an active CRS (carrier sense) signal on the GMII/MII. Defer time is not cumulative. If the transmitter defers for 10,000 bit times, then transmits, collides, backs off, and then has to defer again after completion of back-off, the deferral timer resets to 0 and restarts.
When this bit is reset, the deferral check
function is disabled and the GMAC defers until the CRS signal goes inactive.

3

RW

0x0

TE
Transmitter Enable
When this bit is set, the transmit state machine of the GMAC is enabled for transmission on the GMII/MII. When this bit is reset, the GMAC transmit state machine is disabled after the completion of the transmission of the current frame, and will not transmit any further frames.

2

RW

0x0

RE
Receiver Enable
When this bit is set, the receiver state machine of the GMAC is enabled for receiving frames from the GMII/MII. When this bit is reset, the GMAC receive state machine is disabled after the completion of the reception of the current frame, and will not receive any further frames from the GMII/MII.

1:0

RO

0x0

reserved


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