IGEP
TM
SMARC iMX6
Hardware Reference Manual
ISEE 2007 S.L. All rights reserved, IGEP is a registered trademark from ISEE 2007 S.L. The following is provided for informational purposes only.
NIF:ESB64377005 Document:
MAN-IGEP0046-001
/ Revision:
1.3
/ Date:
23/06/2016
17
4.4
ETHERNET
The module can be connected to a standard 10 or 100 or 1000 Mbps Ethernet system. For this function, there
is a block of pins in the SMARC-314 that can be connected directly to the Ethernet LAN. MDI lines are
differential (in the pin function is indicated the Negative and Positive) and they should be connected to
isolation magnetics. The data lines have to be equal length and symmetric, and respect a 100Ω differential
impedance in the layout traces. The differential pairs must be isolated from nearby signals and circuitry to
maintain the signal integrity.
Moreover, the magnetics module has a critical effect so it has to be designed carefully. In order to obtain a
smaller size, it’s usual to use RJ45 connectors with the magnetics incorporated. If the magnetics are discrete
components, they have to respect a separation under of 25mm between them and the RJ45 connector, and
20mm or greater between them and the SMARC-314 connector.
There are also two outputs to manage LEDs. These LEDs are used to indicate the good functioning of the
Ethernet connection. The first one (output GBE_LINK100#, usually a yellow LED) gives an indication about
the line link (LED off for no link and LED on for valid link). The other (output GBE_LINK_ACT#, usually a green
LED) gives an indication about the line activity: LED on indicates a valid link; when LED is blinking there is
data traffic.
In the next figure (page 69 of SMARC Design Guide) is shown an example of connection diagram, using a RJ45
jack with integrated magnetics.
