KSZ9031RNX-EVAL Board User’s Guide
Micrel, Inc.
August 17, 2012
Rev.
1.1
11/22
4.5 Reduced Gigabit Media Independent Interface (RGMII)
The KSZ9031RNX-EVAL board provides open access to the KSZ9031RNX device’s RGMII
signals, and enables the RGMII signals to be wired for the following two usages:
•
RGMII Loop Back
•
RGMII Connection to GMAC
4.5.1 RGMII
Loop
Back
The KSZ9031RNX-EVAL board is shipped with the RGMII signals configured for RGMII Loop
Back. Resistors [R14, R16, R136-R139] are populated to connect the RGMII output clock and
signals to their respective RGMII input clock and signals, thru resistors [R18, R17, R143, R142,
R141, R140], respectively. Refer to KSZ9031RNX-EVAL Board Schematic for details.
RGMII Loop Back enables the KSZ9031RNX device to operate as a standalone evaluation
platform without the need of an external GMAC. Ethernet traffic from the link partner (Spirent
SmartBits 6000B in the following figure) are received by the KSZ9031RNX device, looped back
externally via RGMII pins, and transmitted back to the link partner.
Figure 2. KSZ9031RNX-EVAL Board – RGMII Loop Back
RGMII Loop Back is supported for 1000Base-T and 100Base-TX only. 10Base-T requires a MAC
due to preamble consumption, and therefore is not supported.
