How I worked around startup issues with pynq z1

Support
1

I wrote the image to the SD card, inserted it. But jupyter only showed a blank screen.
after seeing that the jupyter service crashed after some time, I decided to run it manually, only to get

 Exception: You must define the 'cookie_secret' setting in your application to use secure cookies

when connecting to the server.

Turns out, something was wrong with the config… after some googling I figured out it had to do with the tornado security. So to hack a fix for this, I changed
/home/root/.jupyter/jupyter_notebook_config.py
I uncommented the line and added the b’anything’
c.NotebookApp.cookie_secret = b’anything’
and tested if it worked by running
jupyter-lab --allow-root as root
This worked for me.

2

Thanks for sharing this.

Could you let us know the following?:

  • Which version of PYNQ are you using?
  • Which OS/Browser?
  • Which IP are you using to connect to PYNQ and is your board connected to the internet?

Cathal

3

I’m using pynq z1, connected with an ethernet-usb dongle to my windows 10 laptop
using a version 2.5 image from xilinx downloads.
Note that after changing the setting, I can connect normally from boot, and everything seems to work fine.

– Magnus

4

I had the exact same issue with my PYNQ Z2, using the PYNQ 2.5 image from Xilinx. Tried 2 different ways of flashing the SD-card with the image, and it was the same each time. Started up, no blinking LEDs, and jupyter crashing with complaints about that secret.

I tried your solution and it worked. Then the next time I booted it up, it went into a reboot loop, so I suspected it was a power issue. Unplugged it from my USB-hub and plugged it directly into the computer, and it booted up without issue. And I also saw the LEDs flashing for the first time.

So suspecting it might have been a power issue all along, I reflashed the SD-card to get rid of any changes I did and booted it up. And it worked perfectly.

I can see it’s drawing upwards of 0.61 amps during boot, and maybe that’s too much for my USB-hub.

Just posting this in case anyone else has this strange issue. Could be a simple solution.

1 Like
5

I also had the boot loop problem which after power on / off went completely dead. So now power supply doesn’t even turn on the initial red led.

So after your hint, I unplugged the power supply, changed jumper from REG to USB and used USB for power. It started up, but a minute or so after os booted up, it rebooted and is now in boot loop again.