Using UART3

Has anyone been able to enable and use UART3 (ttyO3) on the Beaglebone Black? Any tips or tricks to share?

Access to uart3_rxd is not available on the headers...

Regards,

Thank you for your input. You cannot enable uart3_txd?

Sure you can enable that one:

https://github.com/beagleboard/bb.org-overlays/blob/master/src/arm/BB-UART3-00A0.dts

Just add:

cape_enable=bone_capemgr.enable_partno=BB-UART3

to /boot/uEnv.txt

Regards,

Thank you, Robert, for the tips and files. Still not having luck with enabling the uart3_txd. With the github file, linked above, does that have to be put in a special place and does it need compiled? Also, can the other uarts be enabled along with the uart3_txd? Normally, I include this “cape_enable=capemgr.enable_partno=BB-UART1,BB-UART2,BB-UART4,BB-UART5” in my uEnv.txt file so I can enable those uarts. I have tried issuing adding the line you sent me, “cape_enable=bone_capemgr.enable_partno=BB-UART3”, both with and without my normal line and still not seeing the uart3_txd(ttyO3) listed in device list.

I appreciate your help with this matter.

Regards,

Mike

cape_enable=capemgr.enable_partno=BB-UART1,BB-UART2,BB-UART3,BB-UART4,BB-UART5

Regards,

Assuming he’s using one of the newer images,
Any reason it can’t be done with config-pin instead of an overlay?

What image do I need to be using, in order to use the uart3_txd? I am currently using Debian, version 3.8.13-bone79.

I apologize for bothering you again. I seem to be having a problem compiling the BB-UART3-00A0.dts file that you sent me a link to. Here is the command I issue to compile it. “dtc -O dtb -o BB-UART3-00A0.dtbo -b 0 -@ BB-UART3-00A0.dts” I have tried several times and have received the following error

“Error: BB-UART3-00A0.dts:11.1-9 syntax error
FATAL ERROR: Unable to parse input tree”

is there a trick or something special I need to do to compile it to get it to compile correctly?

Thanks again,

Mike

Well it doesn't matter as you are using 3.8.13-bone79

https://github.com/beagleboard/bb.org-overlays

is 4.1.x+ only..

Regards,

dont you love the error when compiling ?
no line number or more infos to help you troubleshoot.

have you modified it in any way ?

i had issues manually compiling so i just used the makefile

make clean then make and if all went well a sudo make install

dont you love the error when compiling ?
no line number or more infos to help you troubleshoot.

The issue, he didn't run gcc pre-proccessor on it. :wink:

Easier to just run make in the included makefiel..

have you modified it in any way ?

i had issues manually compiling so i just used the makefile

make clean then make and if all went well a sudo make install

Regards,

Ok. I have made a bit of progress, this afternoon.

I finally was able to get the file you sent me to compile with the dtc version that I have. The only problem, is it is not assigning BB-UART3 to /dev/ttyO3 for use. Attached is my updated “.dts” file.

Thanks again for your help.

Regards,

Mike

BB-UART3-00A0.dts (1.74 KB)

if you are still using 3.8.13, see this:

https://github.com/beagleboard/linux/blob/3.8/firmware/capes/BB-UART4-00A0.dts#L41

Notice:

target = <&uart5>; /* really uart4 */

Change your &uart3 to &uart4...

Regards,