Functional Description
14.3.5.2 RMII Transmit (TX)
The CPRMII transmit (TX) interface converts the 3PSW MII input data into the RMII transmit format. The
data is then output to the external RMII PHY.
The 3PSW does not source the transmit error (MII TXERR) signal. Any transmit frame from the CPGMAC
with an error (ie. underrun) will be indicated as an error by an error CRC. Transmit error is assumed to be
deasserted at all times and is not an input into the CPRMII module.Zeroes are output on RMII_TXD[1:0]
for each clock that RMII_TXEN is deasserted.
14.3.6 RGMII Interface
The CPRGMII peripheral shall be compliant to the RGMII specification document.
Features:
•
Supports 1000/100/10 Mbps Speed.
•
MII mode is not supported.
If RGMII is used, and a 10Mbit operation is desired, in-band mode must be used and an ethernet PHY
that supports in-band status signaling must be selected.
14.3.6.1 RGMII Receive (RX)
The CPRGMII receive (RX) interface converts the source synchronous DDR input data from the external
RGMII PHY into the required G/MII (CPGMAC) signals.
14.3.6.2 In-Band Mode of Operation
The CPRGMII is operating in the in-band mode of operation when the RGMII_RX_INBAND input is
asserted.RGMII_RX_INPUT is asserted by configuring the ext_en bit to 1 of the MACCONTROL register.
The link status, duplexity, and speed are determined from the RGMII input data stream as defined in the
RGMII specification. The link speed is indicated as shown in the following table:
RGMII-_SPEED(1:0)
Link Speed
00
10 Mbs mode
01
100 Mbs mode
10
1000 Mbs mode
11
reserved
14.3.6.3 Forced Mode of Operation
The CPRGMII is operating in the forced mode of operation when the RGMII_RX_INBAND input is
deasserted by setting MACCONTROL.EXT_EN to 0. In the forced mode of operation, the in-band data is
ignored if present. In this mode, the contents of RGMII_CTL are meaningless. Link status, duplexity, and
speed status should be determined from the external ethernet PHY via MDIO transactions.
14.3.6.4 RGMII Transmit (TX)
The CPRGMII transmit (TX) interface converts the CPGMAC G/MII input data into the DDR RGMII format.
The DDR data is then output to the external PHY.
The CPGMAC does not source the transmit error (MTXERR) signal. Any transmit frame from the
CPGMAC with an error (ie. underrun) will be indicated as an error by an error CRC. Transmit error is
assumed to be deasserted at all times and is not an input into the CPRGMII module.
In 10/100 mode, the MTXD (7:0) data bus uses only the lower nibble. The CPRGMII will output the lower
nibble twice in 10/100 mode to avoid unnecessary signal switching.
Packets will be precluded from transmission through the CPRGMII module for 4096 transmit clocks after
the rising edge of RGMII_LINK. Packet transmission will begin on the first GMII_MTXEN rising edge after
the 4096 transmit clock count has expired.
1226
Ethernet Subsystem
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated