Tinker Board Forum

Hi,
  We are porting some of our company products (amusement games), currently based on Raspberry Pi3, to your awesome Tinker Board.

We expected a 100% compatibility as regards the 40 pins socket, but if we swap the RPi3 with a Tinker Board, the latter does not boot.
We investigated, and we found that the reason is the UART1: if we disconnect the RX (pin10) and TX (pin8) wires, the Tinker boots normally!

The adapter board takes the UART1 TX/RX connections, and converts them to a CCTALK bus (TTL 5V), and I suppose TX and RX are internally connected together.

It seems that the Tinker at boot time checks something at UART1 TX/RX that prevents booting for some reasons...
If we enable UART2 on the Tinker, and connect RX (pin33) and TX (pin32) to our adapter, it boots normally, so the problem is related to UART1 only.

How can we disable this behavior ?

Thank you very much for your support.
David

Hi David

Can I know what OS and version you use?

Hi,
 we are using the stock image:http://dlcdnet.asus.com/pub/ASUS/mb/Linu...v2.0.4.zip

 The super kind Asus support has just contacted me to suggest a solution!


We need to update the "uboot", recompiling it after applying a patch in order to disable the debug mode.

Thanks

Hi David

As I know, your image just use UART3 as tty for uboot debug mode, not UART1.
so UART1 should not cause device into shell at uboot stage.

However, disable debug mode at uboot is still worth a try.

Hi David

#Give up apply
git am  --abort
#rollback repository
git reset  --hard && git clean -df

And modify “CONFIG_BOOTDELAY=0” at line 71 in configs/tinker-rk3288_defconfig
Then built it.

Hi,
  thanks again! We were able to complete the procedure.

As you imagined, the Tinker still does not boot when UART1 is connected to our custom board...

Any other idea..?
Is it possible to modify the /debian_u-boot/configs/tinker-rk3288_defconfig file in order to "swap" the pins of UART1 and UART2... ?
We have no boot problems if we connect UART2 to our board...

Thank you very much for all your help.
David

Hi David
 
i am sorry, after my check with internal. v 2.0.4 use UART1 as debug tty.
please try "CONFIG_BOOTDELAY=-2", i think it can solve your problem.

Hi David

you can try to update image by following link
https://tinkerboarding.co.uk/forum/thread-1198.html.