Connecting mini DisplayPort to HDMI....How?

[signal]

This may sound like a basic question, but it has me stumped.

I have Raspberry PI's which of course have an HDMI connector.  I would like to connect my Apple Cinema Display to these, but the output of the display is a hard wired mini Display Port.  I have tried some obvious things:

Use a female-to-female mini display port coupler, connect to the RPI using a HDMI to mini Display Port cable
Use a mini Display Port to DisplayPort coupler and connect to the RPI using a HDMI to Display Port cable

Neither of these work, I get no signal.  In fact when reading reviews for many of these coupler type devices I see the same thing, people not having success.

Does anyone know how I can connect a mini DisplayPort male plug easily to a HDMI port on the RPI?  I am trying to avoid having to have a second display on my desk for when I wish to work with the RPI.

Brian

[Richard Crowley]

Although they use the same kind of TMDS channels (4 in DP, and 3 in HDMI), DisplayPort is different than HDMI. 
Many (most?) DisplayPort outputs can be re-configured to output HDMI-like signals so you can use a simple DisplayPort to HDMI cable or adapter.
But, alas, there is no way to do the reverse. If you have a simple HDMI output (as on the RasPi), there is no way to convert it to DisplayPort with a simple adapter.

[signal]

Richard,

Thanks, that is very helpful information that could have saved me some $$$ in numerous cables and connectors .

I wonder if some item exists that will allow for this.  I am going to search, but my guess is its probably too expensive.  Maybe I just buy one of those very small HDMI TFT displays and call it a day for when I need to plug in the RPI's.

Brian

[Richard Crowley]

It appears that there are active HDMI to DP converter boxes that people have successfully used with that screen.
Kanex XD HDMI to Mini Displayport Converter
http://www.amazon.com/Kanex-HDMI-Mini-Displayport-Converter/dp/B003LGOWNQ

[signal]

Thanks for pointing me to that!

[German_EE]

http://www.startech.com/AV/Converters/Video/Active-HDMI-or-DVI-to-DisplayPort-Converter~HDMI2DP

http://www.cablestogo.com/product/54179

http://www.lindy-usa.com/HDMI-to-DisplayPort-4K-Adapter-38146.html

[signal]

Thank you all for the links.