The BeagleBone has six on-board serial ports.
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 /media/BEAGLEBONE/uEnv.txt in an editor (vim/nano)
- Rev C: Open the file /boot/uboot/uEnv.txt in an editor (vim/nano)
- Add the key "capemgr.enable_partno="
- Add the ports you want to enable, comma separated (BB-UART1, BB-UART2. BB-UART4, BB-UART5)
- Reboot
An example line looks like this:root@beaglebone:/dev# cat /media/BEAGLEBONE/uEnv.txt
optargs=quiet drm.debug=7 capemgr.enable_partno=BB-UART4
After reboot, the device is present in the device list: root@beaglebone:/dev# ls -l /dev/ttyO*
crw-rw---- 1 root tty 249, 0 Jan 1 01:18 /dev/ttyO0
crw-rw---- 1 root dialout 249, 4 Jan 1 01:18 /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 | |
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