BeagleBone Black/OpenBSD Serial Install
From Bibliotheca Anonoma
The Beaglebone is capable of installing OpenBSD to it (without support for encrypted partitions), but lacks a driver for its HDMI port. Thus, the OpenBSD installation all has to be done on GUI-less serial port. This means you'll need to find some serial to USB connector.
Connect the following pins to the serial pins on the Beaglebone. The USB converter should have each of its pins labeled on it.
--- Ethernet connector ---
GND -> J1
J2
J3
TXD -> J4
RXD -> J5
J6
--- USB connector ---
Finally, connect to the USB serial device using screen.
sudo screen /dev/ttyUSB0 115200
By default Linux sets the USB to serial converter to /dev/ttyUSB0 unless you have a (non-USB) direct serial connection. In addition, the baud rate is 115200.
