NanoPi Neo 4 serial console - u-boot text unreadable. Works once booted.

[Jim MacKenzie]

Hi,

 

I have deployed a NanoPi Neo 4 and for the most part, I'm happy with it, but am having a peculiar problem.

 

I am using the manufacturer-supplied serial console cable and USB adapter (via screen /dev/ttyUSBx 115200).  Once the machine is properly booted, if I hit enter, I get a serial console as normal.  However, I get garbage from u-boot (and presumably from the kernel boot messages).  It looks just as if I have a speed mismatch.

 

I have tried many other speeds (1500000, 230400, 57600, 38400, 19200, 9600) and none of these seem to work.

 

What am I doing wrong?  Or is the state of the box right now that u-boot sends garbage through the serial port?

 

I'm having a bit a problem with the box (it may be power-related) and being able to see the console would be a huge help.

 

Thanks!

 

Jim

[martinayotte]

1 hour ago, Jim MacKenzie said:

via screen /dev/ttyUSBx 115200

The RK3399 SoC is defaulted to 1500000 and the U-Boot too...

[Jim MacKenzie]

2 minutes ago, martinayotte said:

The RK3399 SoC is defaulted to 1500000 and the U-Boot too...

 

I tried that, and I still got garbage.  I'll give it another go, though.

[Jim MacKenzie]

Confirmed, I get garbage at 1500000 bps as well.  I also tried 230400, 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1200 and 300, out of desperation.

 

The UART/USB adapter says it's USB 2.0 but lsusb -v shows it's only connected at 1.1 speeds.  I doubt this should matter - 1.1 can still handle 1.5Mbps - but thought I should mention it.

[Jim MacKenzie]

I got it working by moving the USB cable to another machine.  Maybe it's some weird USB-port incompatibility with 1.5Mbps.  (It used to be plugged into an old ARM box - the box that the new NanoPi is replacing - but is now plugged into a Core 2 Duo desktop, also running Linux.)

 

I still don't get any kernel booting messages (any way to force this to happen?) but I see the u-boot messages, at least, and was able to diagnose my problem and get the NanoPi booted again.

[martinayotte]

14 hours ago, Jim MacKenzie said:

I still don't get any kernel booting messages (any way to force this to happen?)

If you mean that you don't see any kernel logs after "starting kernel", make sure that /boot/armbianEnv.txt have "console=serial" and "verbosity=7" ...

[Jim MacKenzie]

17 minutes ago, martinayotte said:

If you mean that you don't see any kernel logs after "starting kernel", make sure that /boot/armbianEnv.txt have "console=serial" and "verbosity=7" ...

That's exactly what I mean.  I'll make that tweak.  Thanks!