BBIO Library - UART3 & UART5

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Billwaa
 
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Joined: Wed Apr 16, 2014 11:10 pm

BBIO Library - UART3 & UART5

Post by Billwaa »

Hi,

I am trying to enable UART 1 to 5 at boot without log in. It's for a quadcopter project where the BBB is the flight computer. So I wrote a python script and launch it at boot using Cron.

When I do a "dmesg | grep tty", I get the following:

Code: Select all

[    0.000000] Kernel command line: console=tty0 console=ttyO0,115200n8 root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait fixrtc quiet init=/lib/systemd/systemd
[    0.000000] console [tty0] enabled
[    0.535141] 44e09000.serial: ttyO0 at MMIO 0x44e09000 (irq = 72) is a OMAP UART0
[    0.547010] console [ttyO0] enabled
[   16.415168] 48022000.serial: ttyO1 at MMIO 0x48022000 (irq = 73) is a OMAP UART1
[   16.657944] 48024000.serial: ttyO2 at MMIO 0x48024000 (irq = 74) is a OMAP UART2
[   17.151622] 481a8000.serial: ttyO4 at MMIO 0x481a8000 (irq = 45) is a OMAP UART4
So I guess UART 1 ,2 and 4 works. What about UART 3 and 5?
I know UART 3 only have a TX, but I only use it to communicate one way to a pwm controller.

I was able to use the device tree files here and manually enable 3 and 5.
http://www.armhf.com/beaglebone-black-s ... tbo-files/

But when I edit the /boot/uboot/uEnv.txt , it gave me error trying to enable them.
Surprisingly, when I use the built-in BB-UART5, it works.
But there is no built-in BB-UART3.

Thanks,

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adafruit2
 
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Re: BBIO Library - UART3 & UART5

Post by adafruit2 »

we haven't added support for every possible combination of BBB I/Os yet to the BBIO library, so right now i'd say you may have to use the manually implemented device tree overlay. if you have a patch to add support please submit a github pull, it would be greatly appreciated :)

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Billwaa
 
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Re: BBIO Library - UART3 & UART5

Post by Billwaa »

adafruit2 wrote:we haven't added support for every possible combination of BBB I/Os yet to the BBIO library, so right now i'd say you may have to use the manually implemented device tree overlay. if you have a patch to add support please submit a github pull, it would be greatly appreciated :)
hi, I got it figured out by modifying the "am335x-boneblack.dtb" in the /boot/uboot/dtbs directory. In this case, I don't even have to use the BBIO library to setup the UARTS at launch, it does it automatically. I don't know how to use github, but, I basically follow directions in the comments of this page near the bottom:
http://www.armhf.com/beaglebone-black-s ... tbo-files/

UART3 is different in that you only have to define the TX pins "pinctrl-single,pins = <...>"

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