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MSC SM2S-IMX8M User Manual
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4.2 Ethernet
Based on Texas Instruments
™ DP83867 Ethernet controller the module provides 10/100/1000 Mbps Ethernet with MDI differential pairs for an
external transformer.
The DP83867 includes a voltage mode line driver
so it doesn’t require an analog powered center tap. Therefore Pin P28 GBE0_CTREF specified in
the SMARC
™ specification 2.0 is not connected on the module.
The DP83867 has built in termination resistors. As a result, no external termination resistors should be used. Please refer to the DP83867EVM
schematics for correct magnetics wiring. Each Center tap of the magnetics should be independently de-coupled to ground via a 0.1µF capacitor.
Table 4-2: Ethernet Signal Description
Signal
Pin Type
Signal
Level
Pin on i.MX8M
pin name on i.MX8M
Power
Tolerance
PU/PD Description
GB
GBE0_MDI0-
I/O
Analog
n.a.
n.a.
3.3V
Media Dependent Interface Differential Pair 0
Used for the receive pair in 10/100 Mbit/s mode
GB
GBE0_MDI1-
I/O
Analog
n.a.
n.a.
3.3V
Media Dependent Interface Differential Pair 1
Used for the transmit pair in 10/100 Mbit/s
mode
GB
GBE0_MDI2-
I/O
Analog
n.a.
n.a.
3.3V
Media Dependent Interface Differential Pair 2
This signal pair is only used for 1000Mbit/s
mode.
GB
GBE0_MDI3-
I/O
Analog
n.a.
n.a.
3.3V
Media Dependent Interface Differential Pair 3
This signal pair is only used for 1000Mbit/s
mode.
GBE0_LINK_ACT#
O PP
3.3V
CMOS
n.a.
n.a.
3.3V
Link/Activity Indication, active low, 24mA output
drive.
GBE0_LINK100#
O PP
3.3V
CMOS
n.a
n.a
Link Speed Indication for 100Mbps, active low,
24mA output drive.
GBE0_LINK1000#
O PP
3.3V
CMOS
n.a.
n.a.
3.3V
Link Speed Indication for 1000Mbps, active low,
24mA output drive.
NOTE:
If only 10/100 Mbit/s is required, the unused MDI Pins can be left unconnected.