The AM261x controlSOM routes two instances of the AM261x MCU on-die programmable real-time unit and industrial communication subsystem (PRU-ICSS) to the SOM HD connectors. On the HSEC180ADAPEVM-AM2, there are two external Ethernet ports - one on-board gigabit Ethernet PHY transceiver (DP83869), and one Ethernet add-on board connector. The gigabit Ethernet PHY is connected to the PR0_PRU0 core of the PRU-ICSS, and the Ethernet add-on board interface is connected to the PR0_PRU1 core of the PRU-ICSS. Table 2-12 details the protocols supported at each Ethernet port interface:

The Ethernet data signals of the DP83869 PHY are terminated to a RJ45 connector. The RJ45 connector supports Ethernet speeds of 10/100/1000 Mbps connectivity and has integrated magnets and LEDs for link and activity indication.

There are a series of multiplexers on the paths of the PRU-ICSS nets from the SOM HD connectors to their external interfaces. 3 high-speed, 12-channel switches (TS3DDR3812) control the routing of the PRx_PRUx_GPIOx signals to either the Ethernet interfaces or to the HSEC connector. The select lines for the muxes are software controlled by two output signals configured by the on-SOM IO Expander, or hardware controlled by the on-board switches (SW3 and SW4) on the HSEC180ADAPEVM-AM2. An additional mux selects which set of MDIO signals is routed to the DP83869 PHY, and is dependent on which protocol is being used on the DP83869 - CPSW RGMII or PRU MII. The select line of this mux is controlled by AM261x GPIO74, which is routed from the MCU to the HSEC180ADAPEVM-AM2 through SOM HD connector J2. Table 2-13 shows the mux configurations. Figure 2-18 shows the mux select switches.