UART header pin locations?

I’m looking through the BeagleBone System Reference Manual, and I can’t seem to find the UART3_RXD on the headers. In looking through the /sys/kernel/debug/omap_mux, It’s mux 2 on the spi0_cs1.gpio0_6, but I cant find that either.

root@beaglebone:/sys/kernel/debug/omap_mux# cat spi0_cs1
name: spi0_cs1.gpio0_6 (0x44e10960/0x960 = 0x0037), b NA, t NA
signals: spi0_cs1 | uart3_rxd | NA | mmc0_pow | NA | mmc0_sdcd | NA | gpio0_6

Anybody know how to get to this?

All the pins are not accessible. Read section 6.3.6.

6.3.6 Serial Ports

There are four serial ports on the expansion headers. UART ports 1, 2, 4 ports have

TX,Rx,RTS and CTS signals while UART5 only has TX and RX.

You will see UART3 is not listed. Due to pin usage on the board, all of the UART3 signals are not on the expansion header.