June 27, 2018

A serial console for the Beaglebone Black

I view this as a necessity.

The board has a 6 pin header (marked J1 on my BBG and my BBB) that is parallel to and very close to P9. You need to connect to 3 pins on this header. Hold the board with P9 close to you and the network jack on the left.
Then, from left to right, the 6 pins are:

  1. Ground
  2. ---
  3. ---
  4. Rx
  5. Tx
  6. ---
There is a tiny dot next to pin 1 on the silkscreen.

Note that the logic levels are 3.3 volts. Be sure whatever you connect to this header does not try to drive levels to 5 volts. Don't connect to the other pins. I forget what they are and am too lazy right now to check the schematic and find out.

There are many USB to serial gadgets that can be used. I buy cheap CP2102 based things from China for $2 each. These usually will not directly plug onto the BBB though and some fiddling is required. The following are more expensive, but perhaps more convenient.

You will want to connect Rx on your "cable" to Tx on the BBB (and likewise Tx to Rx). It at first it does not work, try it the other way.

I use picocom on my linux system, with the following command: 

picocom -b 115200 /dev/ttyUSB0
The actual USB serial device may be different, depending on your system and what other USB gadgets you have plugged in. Some people like "screen" instead of picocom. If you use windows, you may find Putty useful.

Feedback? Questions? Drop me a line!

Tom's Computer Info / tom@mmto.org