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Serial ports on the Beaglebone Black

On the BeagleBone Black, it's only the /dev/ttyO0 that is enabled by default, and it is coupled to the serial console. The other serial ports must be enabled before they can be used. To enable the uarts 1,2,4 and/or 5 on the BeagleBone Black, rev A, B and C: Rev A/B: Open the file sudo nano/media/BEAGLEBONE/uEnv.txt Mine is Rev C: So sudo nano  /boot/uboot/uEnv.txt Add the key "capemgr.enable_partno=" Add the ports you want to enable, comma separated (BB-UART1, BB-UART2. BB-UART4, BB-UART5) In my case I want to add tty04 so I can hook up to the RF Transmitter and LCD of my home automation  Reboot An example line looks like this: ubuntu@beaglebone:~$ sudo nano /boot/uboot/uEnv.txt Find a suitable line to edit e.g. ##Disable HDMI cape_disable=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN capemgr.enable_partno=BB-UART4 After reboot, the device is present in the device list: ubuntu@beaglebone:~$ ls -l /dev/ttyO* crw-rw---- 1 root tty     248, 0 Jul  1 20:39 /dev/ttyO0 crw-rw---- 1 root dialout 248, 4 Jul  1 20:39 /dev/ttyO4 The UARTs map to pins and devices like this:  RX  TX  CTS  RTS  Device  Remark  UART0     J1_4  J1_5      /dev/ttyO0 BeagleBone Black only  UART1  P9_26  P9_24  P9_20  P9_19  /dev/ttyO1  UART2  P9_22  P9_21  P8_37  P8_38  /dev/ttyO2  UART3  P9_42  P8_36  P8_34  /dev/ttyO3  TX only  UART4  P9_11  P9_13  P8_35  P8_33  /dev/ttyO4  UART5  P8_38  P8_37  P8_31  P8_32  /dev/ttyO5