And just what do you think the OS under Android is? I'll grant you that it is hidden away pretty well... (Likewise, OS/X is unix in a clever plastic disguise.)ViewTouch wrote:Linux has been quite shut out of the tablet & smartphone device market....
No idea. However I'm here as I've just found the RPi will power my HDMI passthru box which also splits Toslink optical and two line level out just fine.rpdom wrote:Why are you replying to a three year old post? The poster in question hasn't posted since then.
Thats strange as new PI's even use a specific IC (the RT9741CGV-ND) to block current going into the PI from the 50mA 5V wire used to power the EEPROM in the HDMI monitor, and to limit current flowing out. Older PI's used a simple (BAT54) Schottky diode, but that sometimes burned out, especially when using a cheap HDMI to VGA adapter that "stole" power from the EEPROM, and used much more than 50mA.
Talked to a HW guy who knows HDMI, this is nonsense. Please don't try this at home.glenenglish wrote: ↑Fri Aug 31, 2018 6:23 ameveryone has been barking up the wrong tree
HDMI lends it self to powering the device common mode, just like PoE
If the data rate isn't too high, say 25fps SD, , then it probably will work with standard PoE transformers for ethernet.
do some reading on how PoE works.
you'll be good up to 50W easily done right
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-----------. .-------- _|_ _|_ Pi | |================================| | TV | |================================| | .--. | | | | --|5V|-->|___|------------------------------->|___|--> 5V `--' | Pin 18 Pin 18 | -----------' `--------
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Splitter Injector -----------. .-------. .-------. .-------- _|_ |_ _| |_ _| _|_ Pi | |===| |===| |========| |===| |===| | TV | |===| |===| |========| |===| |===| | .--. | | | | | | | | | | | | --|5V|-->|___|---|_| .-|_|<-------|_|-.-|_|-->|___|--> 5V `--' | | | | -----------' | | .--. `-------- 5V <--' `--|5V|--< `--'
I was initially puzzled as well.
That appears to be as per official HDMI specification. Pin 18 on a display is 5V @ 50mA input. It is a sink only, never a source.
Thanks for explaining this! I use one of those powered VGA to HDMI converters and I noticed one time that upon cutting the normal power source that the Raspberry Pi did not shut off. Only after unplugging the HDMI cable did it power off. I thought "Great! I can power a Raspberry Pi using HDMI!" But, as you mentioned I could not get it to power up using HDMI power, only maintain its powered on status.hippy wrote: ↑Mon Sep 30, 2019 11:37 amI was initially puzzled as well.
First the display should not be putting 5V out over HDMI and, even if it does, it would not be expected to be of sufficient current to power a Pi 3, but it is feasible some display's could
And then, if any 5V did reach the Pi 3 I was not expecting it to be able to back-feed through the RT9741CGV high-side switch and power the board's main 5V line.
However, re-reading the datasheet; "If VOUT is greater than VIN, current will flow from VOUT to VIN since the MOSFET is bidirectional when on".
If a Pi is being powered by normal means, with 5V injected on Pin 18 of its HDMI socket, it seems it can continue to draw its 5V through that even when the normal power were removed.
It seems the Pi can continue to be powered through HDMI, but not powered-up by that means.