Electronic – What are all of the pins of the Beaglebone Black Rev. C serial (debug) header

beaglebone blackrs232serial

The Beaglebone Black Rev. C has a serial debug header with 6 pins. I would like to know what each of these pins is. If numbered 1-6 starting closer to the 5v barrel connector, pin 1 is ground, pin 4 is RX, and pin 5 is TX. What are the other pins? Are they NC (not connected)? do any supply any power? Can they safely have an applied voltage (3.3V, 5V, or other)? Consider that most FTDI cables, which match up to the Tx/Rx/Gnd header pins, have a supply voltage output that would line up with header pin 3 (as I have defined the numbering). Are the other pins functional RTS and CTS, as would match up with the FTDI connections? What are the safe/recommended voltage ranges for pins?

Best Answer

There is a schematic available here: http://elinux.org/Beagleboard:BeagleBoneBlack#LATEST_PRODUCTION_FILES_.28C.29

See page 4. Looks like J1 (the UART0 serial port) has only three of the six pins connected - ground, TX, and RX. The others are NC, so you can apply any reasonable voltage to them. Looks like it is designed to work with a USB to TTL serial cable. The TX and RX signals pass through a 74LVC2G241 dual tristate non-inverting buffer/driver that is powered by the 3.3 volt supply. The inputs are 5v tolerant.

The CTS pin of the UART is not connected while the RTS pin is brought out as TP9.

By the way, those are some of the longest pin names that I have seen.