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3.2.6
Gigabit Ethernet signals
The Gigabit Ethernet interface is realised, on Q7-C25 module by using a Texas Instruments DP83867CRRGZR Gigabit Ethernet transceiver, which is interfaced to
NXP i.MX 8M processor through an RGMII interface.
Here following the signals involved in PCI express management
GBE_MDI0+/GBE_MDI0-: Media Dependent Interface (MDI) I/O differential pair #0
GBE_MDI1+/GBE_MDI1-: Media Dependent Interface (MDI) I/O differential pair #1
GBE_MDI2+/GBE_MDI2-: Media Dependent Interface (MDI) I/O differential pair #2, only used for 1Gbps
Ethernet mode (not for 10/100Mbps modes)
GBE_MDI3+/GBE_MDI3-: Media Dependent Interface (MDI) I/O differential pair #3, only used for 1Gbps
Ethernet mode (not for 10/100Mbps modes)
GBE_ACT#: Ethernet controller activity indicator, Active Low Output signal, electrical level +3.3V_RUN with
10k pull-up resistor
GBE_LINK#: Ethernet controller link indicator, Active Low Output signal, electrical level +3.3V_RUN with10k
pull-up resistor
GBE_LINK100#: Ethernet controller 100Mbps link indicator, Active Low Output signal, electrical level
+3.3V_RUN with 10k pull-up resistor
GBE_LINK1000#: Ethernet controller 1Gbps link indicator, Active Low Output signal, electrical level +3.3V_RUN
with 10k pull-up resistor
These signals can be connected, on the Carrier board, directly to an RJ-45 connector, in order to complete the Ethernet interface.
Please notice that if just a FastEthernet (i.e. 10/100 Mbps) is needed, then only MDI0 and MDI1 differential lanes are necessary.
Unused differential pairs and signals can be left unconnected. Please look to the schematic above as an example of implementation of Gigabit Ethernet connector.
In this example, it is also present GBE_CTREF signal connected on pin #2 of the RJ-45 connector. DP83867 PHY
centre tap, therefore the signal GBE_CTREF is not available on Qseven
Q7-C25
Q7-C25 User Manual - Rev. First Edition: 1.0 - Last Edition: 1.0 - Authors: S.B. and A.R - Reviewed by N.P. - Copyright © 2020 SECO S.p.A
®
golden finger connector
D2
R1
R-249
GBE_LINK1000#
G
D1
R2
R-249
GBE_LINK100#
2
GBE_CTREF
9
GBE_MDI0+
10
GBE_MDI0-
7
GBE_MDI1+
8
GBE_MDI1-
5
GBE_MDI2+
6
GBE_MDI2-
3
GBE_MDI3+
4
GBE_MDI3-
1
D4
R3
R-249
GBE_ACT#
G
D3
R4
R-249
GBE_LINK#
CN1
Y
1
75
0.1uF
2
3
75
0.1uF
6
4
75
0.1uF
5
7
75
0.1uF
8
1000pF
2kV
Y
SHIELD GND
LPJG16314A4NL
28
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