codeshift
Posts: 2
Joined: Tue Sep 25, 2012 11:31 pm

HDMI Handshake Issues?

Wed Sep 26, 2012 12:20 am

Hello everyone,
I just received my Raspberry Pi after 6 months of long waiting!
I've noticed some strange behavior on the HDMI.

If I try to POWER ON the Pi with no HDMI cable plugged in and I plug it in after boot,I get NO SIGNAL.
However,if my TV is already ON and then POWER ON the Pi,I get perfect signal without any problems.

I only resolved this by enabling "hdmi_force_hotplug".

Is this a normal behavior or it's something wrong with the HDMI handshaking?
Should the TV be ON before POWERing ON the Raspberry?
I've tried 2 different HDMI TV/Monitors and nothing changed.

Thanks in advance.

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5318
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: HDMI Handshake Issues?

Wed Sep 26, 2012 9:26 am

That is expected behaviour.

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Burngate
Posts: 5972
Joined: Thu Sep 29, 2011 4:34 pm
Location: Berkshire UK Tralfamadore
Contact: Website

Re: HDMI Handshake Issues?

Wed Sep 26, 2012 10:03 am

As the Pi is booting, it looks for an HDMI connection; if it finds none it reverts to composite. "hdmi_force_hotplug" forces it to use HDMI even if no HDMI connection is found.

Some HDMI monitors will communicate even on standby, others only when on, and yet others only when switched to the correct input.

codeshift
Posts: 2
Joined: Tue Sep 25, 2012 11:31 pm

Re: HDMI Handshake Issues?

Wed Sep 26, 2012 10:41 am

Thanks for your fast reply.I'm happy to know this is normal,thanks again!

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