SPRUIV7B May 2022 – September 2023 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP
Figure 12-125 shows a device with integrated EMAC and MDIO interfaced via a RMII connection in a typical system. The individual CPSW0 and MDIO signals for the RMII interface are summarized in Table 12-142.
The CPSW0 module integrated in the device supports internal and external clock sources in RMII mode. Figure 12-125 shows the internal clock source for RMII_MHZ_50_CLK clock. It is 50 MHz clock source that is provided on the CLKOUT0 device pin. This clock has to be routed on the PCB to the RMII_REF_CLK device pin and the external PHY, RMII clock input.
For more information, refer to either the IEEE 802.3 standard or ISO/IEC 8802-3:2000(E).
Figure 12-126 shows the external clock source for RMII_MHZ_50_CLK clock. In this case a 50 MHz clock is available on the PCB and it can be sourced from an oscillator or from the Ethernet PHY. This externally generated clock should be routed to both RMII_REF_CLK device pin and the external PHY, RMII clock input.
Signal(2) | Device Pin(s) | I/O(1) | Description |
---|---|---|---|
RMIIn_TXD[1:0] | RMIIn_TXD[1:0] | O | Transmit data. The transmit data pins are a collection of 2 bits of data. TXD0 is the least-significant bit (LSB). The signals are synchronized by RMII_MHZ_50_CLK and valid only when RMIIn_TX_EN is asserted. |
RMIIn_TX_EN | RMIIn_TX_EN | O | RMII transmit enable. The transmit enable signal indicates that the RMIIn_TXD[1:0] pins are generating data for use by the PHY. RMIIn_TX_EN is synchronous to RMII_MHZ_50_CLK. |
RMII_MHZ_50_CLK | RMII_REF_CLK | I | RMII 50MHz reference clock. |
The reference clock is used to synchronize all RMII signals. RMII_MHZ_50_CLK must be continuous and fixed at 50 MHz. | |||
RMIIn_RXD[1:0] | RMIIn_RXD[1:0] | I | Receive data. The receive data pins are a collection of 2 bits of data. RXD0 is the least-significant bit (LSB). The signals are synchronized by RMII_MHZ_50_CLK and valid only when RMIIn_CRS_DV is asserted and RMIIn_RX_ER is de-asserted. |
RMIIn_CRS_DV | RMIIn_CRS_DV | I | Carrier sense/receive data valid. Multiplexed signal between carrier sense and receive data valid. |
RMIIn_RX_ER | RMIIn_RX_ER | I | Receive error. The receive error signal is asserted to indicate that an error was detected in the received frame. |
MDIO_MCLK | MDIO0_MDC | O | Management data clock (MDIO_MCLK). The MDIO data clock is sourced by the MDIO module on the system. It is used to synchronize MDIO data access operations done on the MDIO0_MDIO data pin. |
MDIO_MDIO | MDIO0_MDIO | I/O | MDIO data pin drives PHY management data into and out of the PHY by way of an access frame consisting of start of frame, read/write indication, PHY address, register address, and data bit cycles. The MDIO0_MDIO pin acts as an output for all but the data bit cycles at which time it is an input for read operations. |