BBB UART question for newbie

Hello all BBB users

i’m looking for the number of FREE UART available (need only RX/TX pins, no handshake on the different connectors of the boards.

I search on the BBB_SRM.pdf, and found on page 54, table 5 : 6 UART available on the processor.
the UART0 seem reserved for debug terminal purpose.

I find

UART1 on table 10 (P9 pin 24/26) which are noted UART0 on the right column … what’s wrong ?

UART2 on table 10 (P9 pin 21/22) which are noted UART0 on the right column … what’s wrong ?
UART3 I find only RTS CTS on pin P8 34/36 …?
UART4 on table 12 (P9 pin 11/13) which are, on the other columns, other pin name … ?
UART5 on header P8 (table 11), on mode 4 (and UART2 handshake on mode 6) … I don’t know exactly what is it for now.
UART5 seem shared with LCD pins (table14). but I don’t need LCD on my application. so may I use UART5 ?

so… i’m confuse … for now, I need to know which UART are free and available for the application user ?

thanks for your help, regards

If you don’t need LCD, yes, you can use that pin as a UART.

As I already said, pins can have more that one function based on the pinmux settings. You can have UART0 or UART1 on the same pin, but not at the same time. Pick one. The table shows all of the functions that CAN be on that pin. This process is called pin muxing. Nothing is wrong!

Handshake is RTS and CTS, l suggest you google serial ports or RS232 and learn what those signals do.


I found this tutorial to be useful in setting up my UART port:

Another good place to start is


Hi Gerald.

I am starting with Beaglebone and I need use a LCD, but I need almost 2 UART free.
Can I generate UART by software in any GPIO?.
I will apreciate your answer.
Best regards.

Did you check for other availability?

Bit banging a UART can be done but I doubt you will get the results you want.


Hi Gerald.


I working with Microchip microcontrollers, and I can create a UARTS by software with it.

I don´t know if that is possible in Beaglebone.

May be exist some library to create UARTs by software and then I could use any GPIO.

I will investigate it, and I will write to you about it.

Other alternative is use the LCD by HDMI connection. In this case the UARts will be free.

Thank you for yours answer.

Best Regards.


It is possible, but the Linux OS may not help in that effort.