ZHCSNO0B April 2021 – November 2021 DP83561-SP
PRODUCTION DATA
All RGMII signals are positive logic. The 8-bit data is multiplexed by taking advantage of both clock edges. The lower 4 bits are latched on the positive clock edge and the upper 4 bits are latched on trailing clock edge. The control signals are multiplexed into a single clock cycle using the same technique.
To reduce power consumption of RGMII interface, TXEN_ER and RXDV_ER are encoded in a manner that minimizes transitions during normal network operation. This is done by following encoding method. Note that the value of GMII_TX_ER and GMII_TX_EN are valid at the rising edge of the clock. In RGMII mode, GMII_TX_ER is presented on TX_CTRL at the falling edge of the GTX_CLK clock. RX_CTRL coding is implemented the same fashion.
where
where
When receiving a valid frame with no error, RX_CTRL = True is generated as a logic high on the rising edge of RX_CLK and RX_CTRL = False is generated as a logic high at the falling edge of RX_CLK. When no frame is being received, RX_CTRL = False is generated as a logic low on the rising edge of RX_CLK and RX_CTRL = False is generated as a logic low on the falling edge of RX_CLK.
TX_CTRL is treated in a similar manner. During normal frame transmission, the signal stays at a logic high for both edges of GTX_CLK and during the period between frames where no error is indicated, the signal stays low for both edges.