How Do I Changed to Debug Port to UART4

[Faruk]

Hello

I working on Olimex-A64 board. I struggle to change debug port from UART0 to UART4. I tried this patch: https://github.com/armbian/sunxi-DT-overlays/blob/master/sun50i-a64/sun50i-a64-uart4.dts#L24 but it is not working. I can't see any character on UART4 when booting. I don't have so much experience on .dts file. So I can't be sure if I'm doing it right. Is there anyone who can give any clue or show way about it?

Thanks

[LubOlimex]

Try our repos:

https://github.com/OLIMEX/OLIMEX-sunxi-overlays

https://github.com/OLIMEX/OLIMEX-sunxi-overlays/tree/master/sun50i-a64

[Faruk]

Hi

Thanks for your reply. When I went over the subject again, I saw that I made a mistake about making patches. I follow https://github.com/OLIMEX/OLIMEX-sunxi-overlays this Readme.md instructions and I added uart4 patch.

Thanks

[LubOlimex]

Good! If you decide to test the latest images, there is also script that does it even easier. Check the blog post here:

https://olimex.wordpress.com/2020/04/21/olimage-mainline-linux-images-building-script-for-all-of-our-olinuxino-and-som-boards/

The super use account is root with password olimex. For some different overlays type:

olinuxino-overlay

This script allows enabling different ports and buses - use arrow keys to move up, down, left or right, "space" to enable or disable different interface, once done - press "tab" to move selector down to "ok" and "cancel" options, press "enter" over "ok" or "cancel", if you've made changes restart the board with "reboot now" so that the changes get applied. There is another script:

olinuxino-display

It is used to set different video output options.

[Faruk]

Thank you. I have one more question about this uart4. I activated uart4 and I sent any character on termial to olimex board, it's worked and I saw data in olimex board. However when I tried to opposite so I tried sent data on terminal from olimex board to PC, I could not accomplish. I examined pinout with osiloscope but I could not see anything. Do you have any clue about this problem?

Thanks

[LubOlimex]

Which pin did you use for TX and which for RX? Looking at the schematic PD2 that is TX seems to be used by the Ethernet and LCD. Try different position of the jumper in the middle of the board (open, closed).

[Faruk]

Hello again. I haven't had time for this for a few days. I am back to this job again. I soldered wrong pin. That's way uart work just one way. Now Uart4 working.

Now I try seeing u-boot debug output from uart4(This is so specific desire but I try ). I followed this step https://forum.armbian.com/topic/11301-change-u-boot-uart-on-orangepi-zero/ and change u-boot debug output from uart0 to uart2 on Olinuxino-A64 and it is work easily. However I tried same process for uart4 but it's not working. My patch file is https://github.com/farukkilavuz/uboot-uart4/blob/master/uart4.patch.

The port uart0 and uart2 are connected to GPIO B. So easily switched debug port from uart0 to uart2. But  Uart4 is connected to GPIO D. I think, the reason for the problem is that but I can not sure and I don't know how can I solve this problem. Do you have any idea for this situation?

Thanks