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I've got a Raspberry Pi 2 Model B and a touchscreen that still uses VGA as input. I got myself a passive HDMI-VGA adapter and tried to turn it on but there was no signal coming in at the screen.

I do know now that the RPi outputs a maximum of 200 mA to the HDMI slot.

My idea is to turn the passive adapter into an active one, but I'm not really sure how to do this. After going through some specs and pin layouts I'd try to connect PIN 18 (HDMI) to "+" and PIN 5 (HDMI) to "-" on my power source (a USB cable).

Will that work or should I expect to fry the adapter or even the RPi with this idea?

  • I do not beleive it can be that simple. If it was why are active adapters more expensive than passive ones? – joan Sep 18 '15 at 22:56
  • It's indeed probably not that simple. However, the circuitry cannot be that expensive as I did found working adaptors for about $2 bulk and about $4 retail. Living nextdoor to an el-cheapo Asian electronic mall might help :-) – EDP Sep 19 '15 at 4:05
  • Even if the circuitry was simple and inexpensive, making it will not be - HDMI is high speed interface that uses tiny wires and will suffer from interference if you removed enough shielding to actually do anything with it – user2813274 Nov 19 '15 at 4:39
  • Perhaps raspberrypi.stackexchange.com/questions/222/… can help. My comment there describes that most HDMI-VGA converters probably work fine despite of what others claim. Might need some small tweaking though. – EDP Feb 16 '16 at 12:46
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I'd like to know which cable adapter you have that claims to be "passive". From what I know (check http://www.tomshardware.com/answers/id-2596178/difference-passive-active.html for a good summary, especially the last post), there are 2 "definitions" of active vs passive:

  1. Passive = no external power source required, i.e. all powered from the power supply of the device that contains the source signal.
  2. Passive = no transformation of the signal, i.e. the signal is just rearranged from one input pin to another output pin.

From that definition, the manufacturer of your HDMI-VGA adapter probably used definition #1 as the "passive" description. However, given the fact that HDMI is a digital standard, and VGA is analog, there is no way the adapter could also be "passive" from the perspective of definition #2.

Now to your question's answer: I use a "passive"(definition #1) HDMI-VGA adapter regularly with my rPi's (both B, B+ and 2B) and it works, IF AND ONLY IF I plug in the adapter before the rPi turns on AND the monitor I connect to is already turned on as well. If I try to add my HDMI-VGA adapter while the rPi is running, I get no signal. Can you try this?

If that fails, make sure you have looked at all the HDMI configuration options in /boot/config.txt - perhaps you need to force something there to make the dongle work.

I would NOT start with trying to modify the dongle - it should be properly powered from the rPi's HDMI port ("passive" as per your manufacturer) - the cause is most likely in the two things I mentioned above.

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