Yocto build on Raspberry Pi3 stuck on Rainbow screen

Question

I am trying to learn about Yocto Project on my Raspberry Pi3 board. I have followed the steps mentioned in this link to build the Yocto image.

I am behind a firewall, so I have changed the git.py file to use https instead of git. To be precise I have done below changes

Change 1:

if 'protocol' in ud.parm:
    ud.proto = ud.parm['protocol']
elif not ud.host:
    ud.proto = 'file'
else:
    #ud.proto = "git"
    ud.proto = "http"

Change 2:

repourl = "https://%s%s%s" % (username, ud.host, ud.path)

I am able to build successfully and have extracted the image on to the SD card as instructed in the link. But after loading the SD card on my Pi board, it is stuck in the initial screen (rainbow screen) and I don't see any logs coming on the serial console.

I have also tried by changing machine variable in the conf/local.conf file as mentioned below:

MACHINE ?= "raspberrypi2" 

Am not sure what am missing, any help will be appreciated. Thanks.

Answer 1

If your power supply is good then this elinux.com website states :

In some cases (Stuck on the Rainbow Screen), freezing at this point has been fixed by adding "boot_delay=1" to the config.txt file.

There more troubleshooting guide on that page check it out.

Answer 2

I had a similar issue and I found it was because I wasn't using a powerful enough power adapter for the Pi. It needs to be 2.5A@5V.

When there isn't enough power it hangs on the rainbow screen.