# Beaglebone Black and UART, how to enable

**URL:** <https://forums.balena.io/t/beaglebone-black-and-uart-how-to-enable/373455>\
**Category:** balenaOS\
**Tags:** beaglebone\
**Created:** [January 27, 2025, 2:13pm UTC](https://forums.balena.io/t/beaglebone-black-and-uart-how-to-enable/373455 "2025-01-27T14:13:28Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![cheezymcsquibble](https://avatars.discourse-cdn.com/v4/letter/c/a183cd/32.png) [@cheezymcsquibble](https://forums.balena.io/u/cheezymcsquibble)\
**Post date:** [January 27, 2025, 2:13pm UTC](https://forums.balena.io/t/beaglebone-black-and-uart-how-to-enable/373455/1 "2025-01-27T14:13:28Z")

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Hello, as of 2025 what is the current method to enable UART port on a Beaglebone Black? There seems to be a lot of outdated information on this forum which is not working for me.

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**Author:** ![jaan513](https://avatars.discourse-cdn.com/v4/letter/j/e9bcb4/32.png) [@jaan513](https://forums.balena.io/u/jaan513)\
**Post date:** [January 31, 2025, 2:32pm UTC](https://forums.balena.io/t/beaglebone-black-and-uart-how-to-enable/373455/2 "2025-01-31T14:32:25Z")

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1. Do you need it to enable login via UART?
2. Or to enable using UART for data transfer?

To answer the question **1** I wrote, UART0 (/dev/ttyS0) seems to be enabled by default, but I don’t know if there is a getty listening there. Systemd is running and getty target (which usually refers to login prompt, I guess) is active, but I’m not currently aware how it is set up. I could test hooking up some cables to the serial debug port (UART0), to see what it’s doing.

To answer the question **2** I wrote, I’ve been using other Beaglebone Black UARTs (/dev/ttyS1…/dev/ttyS5 which correspond to UART1…UART5) for data transfer. Running BalenaOS 6.0.32 now.

I separately add these lines on each Balena device (“host OS”) to /mnt/boot/uEnv.txt:

```auto
enable_uboot_overlays=1
uboot_overlay_addr0=/boot/overlays/BB-UART1-00A0.dtbo
uboot_overlay_addr1=/boot/overlays/BB-UART2-00A0.dtbo
uboot_overlay_addr2=/boot/overlays/BB-UART3-00A0.dtbo
uboot_overlay_addr3=/boot/overlays/BB-UART4-00A0.dtbo
uboot_overlay_addr4=/boot/overlays/BB-UART5-00A0.dtbo

```

and reboot.

Note there is only TX (no RX) on UART3.

Using overlays, you can also enable using I2C ports, RTCs etc. The pre-compiled overlays are in “host OS” under /boot/overlays (not /mnt/boot). I’ve used RTCs and I2C sensors with Balena, it should work.

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**Author:** ![cheezymcsquibble](https://avatars.discourse-cdn.com/v4/letter/c/a183cd/32.png) [@cheezymcsquibble](https://forums.balena.io/u/cheezymcsquibble)\
**Post date:** [January 31, 2025, 3:48pm UTC](https://forums.balena.io/t/beaglebone-black-and-uart-how-to-enable/373455/3 "2025-01-31T15:48:38Z")

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Hi, we figured it out in the end, but to me this doesn’t seem like something I can roll out to a fleet of these devices, if i need to manually edit a boot file on each one to get it to read the /ttys01 device … I was hoping it could be done using device configuration variables or dockerfile