MX7D SABRE RGMII2 modification

[demoniacmilk]

Hello Community!

BACKGROUND:

Before creating custom MX7D hardware from scratch I would like to create an addon board for the SABRE and test custom peripherals. This way, all peripherals can be tested with a known-to-work base platform. Once the peripherals are tested, the SoC/RAM/memory etc circuitry/hardware will be created and combined with the peripherals.

ETHERNET:

One of the peripherals is Ethernet and i would like to test my Ethernet Phy circuitry on the addon board.

SMI and RMII signals are needed.

1. SMI:
   • To access the SMI interface a wire could be connected to R271 (pullup MDIO) and R495 (Termination MDC).
2. RMII:
   • ENET2 signals are multiplexed with EPDC signals and should be accessible through the EPDC connector.
   • I need to cut the connection of ENET2 and the SABRE Ethernet Phy. how may i do this? remove U36?
   • Are any additional steps necessary to access the signals? (e.g. adding resistors/bridges)

[igorpadykov · Accepted solution]

Hi Lars

in general you are right:

ENET2 signals are multiplexed with EPDC signals and are accessible through the EPDC connector,

U36 enables RGMII2 signals using ENET_EN_B (GPIO1_IO04).

Best regards
igor
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[demoniacmilk]

So if i pull GPIO1_IO04 high, then U36 "cuts" the connection between Phy and MX7?
Sounds good. Thank you.