The Pi carried on being powered.
"Andy Burns" <usenet@andyburns.uk> wrote
| Unless a 4B is different to any other rPi, they never turn off, they
| just halt.
|
? They have a power switch.
if you made it from scratch you might not have a power
line switch, but it's standard with the kits.
Tim Streater wrote:
The Pi carried on being powered.
Unless a 4B is different to any other rPi, they never turn off, they
just halt.
A bit later I shut it down, **and then turned off the Pi power supply.**
The Pi carried on being powered.
On Wed, 06 Jan 2021 09:44:02 +0000, Mike wrote:
In article <i5kab6FrpbpU2@mid.individual.net>,
Andy Burns <usenet@andyburns.uk> wrote:
Tim Streater wrote:
The Pi carried on being powered.
Unless a 4B is different to any other rPi, they never turn off, they
just halt.
But, from the original post, which you snipped :-
A bit later I shut it down, **and then turned off the Pi power
supply.**
The Pi carried on being powered.
Are you saying the Pi 4B is a stealth free-energy device? ;)
Its not. This just shows that, if there are common positive and ground
rails on the Pi's PCB that are connected to ALL sockets capable of
accepting a connection from an externally powered peripheral device,
which AFAIK is the case for all Pi models, then a Pi will remain active
as long as external device with a power source providing enough current
to keep the RPi alive is connected to it.
It also means that you can destroy a Pi by connecting it to anything
which requires more than 5v to operate and that has its positive and
ground rails connected to the plug it uses to talk to the Pi.
Andy Burns wrote:
Tim Streater wrote:
The Pi carried on being powered.
Unless a 4B is different to any other rPi, they never turn off, they
just halt.
But, from the original post, which you snipped :-
A bit later I shut it down, **and then turned off the Pi power supply.**
The Pi carried on being powered.
Are you saying the Pi 4B is a stealth free-energy device? ;)
In article <i5kab6FrpbpU2@mid.individual.net>,
Andy Burns <usenet@andyburns.uk> wrote:
Tim Streater wrote:
The Pi carried on being powered.
Unless a 4B is different to any other rPi, they never turn off, they
just halt.
But, from the original post, which you snipped :-
A bit later I shut it down, **and then turned off the Pi power
supply.**
The Pi carried on being powered.
Are you saying the Pi 4B is a stealth free-energy device? ;)
OK. So what device is providing the power to the HDMI cables, and
why? In my setup I have a Dell display connected via its DVI (?)
socket and an adapter to a small HDMI switcher that can route the
display either to my Mac Mini or to the Pi.
I did notice that, after disconnecting the HDMI from the Pi, and
reconnecting it (all this with the Pi's power adapter unplugged from
the mains), the Pi did not power up again. So whatever is on teh
HDMI is not a strong power source.
In article <i5kab6FrpbpU2@mid.individual.net>,
Andy Burns <usenet@andyburns.uk> wrote:
Tim Streater wrote:
The Pi carried on being powered.
Unless a 4B is different to any other rPi, they never turn off, they
just halt.
But, from the original post, which you snipped :-
A bit later I shut it down, **and then turned off the Pi power supply.**
The Pi carried on being powered.
Are you saying the Pi 4B is a stealth free-energy device? ;)
Mike wrote:
Are you saying the Pi 4B is a stealth free-energy device? ;)
Ah, someone referring to my OP, instead of rabbiting on about irrelevancies.
Mike wrote:
Andy Burns wrote:
Tim Streater wrote:
The Pi carried on being powered.
Unless a 4B is different to any other rPi, they never turn off, they
just halt.
But, from the original post, which you snipped :-
A bit later I shut it down, **and then turned off the Pi power supply.** >> The Pi carried on being powered.
Are you saying the Pi 4B is a stealth free-energy device? ;)
The Pi is the HDMI source, and the monitor is the HDMI sink, per the
spec the 5V power should be supplied from the Pi to the monitor, not the reverse ...
Tim Streater wrote:
Mike wrote:
Are you saying the Pi 4B is a stealth free-energy device? ;)
Ah, someone referring to my OP, instead of rabbiting on about irrelevancies.
What's relevant is that your monitor shouldn't be reverse feeding 5V to
the Pi
that isn't beset by the software and 'anti pirating' stuff that's in
HDMI.
Andy Burns wrote:
What's relevant is that your monitor shouldn't be reverse feeding 5V to
the Pi
Agreed, if that's what its doing. Could be the other Mini, I suppose. I'll have to do some more testing.
Ah, someone referring to my OP, instead of rabbiting on about irrelevancies.
Chris Green wrote:
that isn't beset by the software and 'anti pirating' stuff that's in
HDMI.
Exactly. And there is another thing. Originally video had to be fast,
for the eye needed at least 70 Hz not to see annnoying flicker. Those
days are long gone. Current dispays are static or buffered. Not all
computing is video or games (though admittedly those are the uses that
bring the revenue in), so cables, buffers and a lot of critical stuff
could be made much easier by reducing to 10 frames per socond or even
less. One frame per second is plenty for many use cases, at least all
those requiring long cables and long distances.
It's a real pity that there isn't really a modern video/display cable
that isn't beset by the software and 'anti pirating' stuff that's in
HDMI.
TimS wrote:
Andy Burns wrote:
What's relevant is that your monitor shouldn't be reverse feeding 5V to >>> the Pi
Agreed, if that's what its doing. Could be the other Mini, I suppose. I'll >> have to do some more testing.
Wouldn't be the biggest surprise in the world if the a cheap switch box
just commoned all the 5V pins together (since it can act as either a 2>1
or 1>2 device, it'll be dumb).
But a source HDMI device is expected to protect itself from an
unexpected 5V arriving into its output, so no harm "should" occur.
They don't. Like Andy said: if you do not physically disconnect the power >plug, the Pi will be halted, not powered off.
Andy Burns wrote:
Wouldn't be the biggest surprise in the world if the a cheap switch box
just commoned all the 5V pins together
Are these 5V signal or power?
From what Joe said upthread, both ends need to
see the other. A 5V signal should suffice for that, I would have thought. No need for the source to be offering to power the remote end.
TimS wrote:
Andy Burns wrote:
Wouldn't be the biggest surprise in the world if the a cheap switch box >>> just commoned all the 5V pins together
Are these 5V signal or power?
Power, but only 55mA
On 06 Jan 2021 at 14:41:25 GMT, Andy Burns <usenet@andyburns.uk> wrote:
TimS wrote:
Andy Burns wrote:
Wouldn't be the biggest surprise in the world if the a cheap switch
box just commoned all the 5V pins together
Are these 5V signal or power?
Power, but only 55mA
Not enough to run a Pi, then, I imagine, but enough to flutter the Pi's red/green LEDs.
On Wed, 06 Jan 2021 15:17:59 +0000, TimS wrote:
On 06 Jan 2021 at 14:41:25 GMT, Andy Burns <usenet@andyburns.uk> wrote:
TimS wrote:
Andy Burns wrote:
Wouldn't be the biggest surprise in the world if the a cheap switch >>>>> box just commoned all the 5V pins together
Are these 5V signal or power?
Power, but only 55mA
Not enough to run a Pi, then, I imagine, but enough to flutter the Pi's
red/green LEDs.
The red LED just shows that power is on - nothing more.
The yellow and green ones show whether the Pi is active: stop a running
Pi with the 'sudo stop' command and all the LEDs go out apart from the
red one, which stays on until you switch off or unplug the wall rat.
That you don't know that shows that you usually stop your Pis by powering them off.
Not a good idea because it can corrupt the SD card - and Murphy
says that you WILL soon or later power it off while the SD card is in the middle of wear balancing - this will cause unrecoverable errors.
Andy Burns <usenet@andyburns.uk> wrote:
The Pi is the HDMI source, and the monitor is the HDMI sink, per the
spec the 5V power should be supplied from the Pi to the monitor, not the reverse ...
I've heard it said that the HDMI spec is a real can of worms.
This thread is just another thing that increases my dislike of HDMI.
Maybe there are use cases where people want to
power their Pis from HDMI, I don't know.
On Wed, 6 Jan 2021 11:19:51 +0000
Chris Green <cl@isbd.net> wrote:
It's a real pity that there isn't really a modern video/display cable
that isn't beset by the software and 'anti pirating' stuff that's in
HDMI.
The software and anti-pirating stuff is HDCP not HDMI. HDCP runs
over HDMI, DVI and DisplayPort as well as USB-3 and will probably be
required in anything new that comes up even though it is essentially
useless. HDMI itself doesn't seem worse than any of the others, better than DVI in that it carries audio as well as video.
Yes, but you can't get an HDMI interface that doesn't implement HDCP
can you? That's the whole point, it prevents (supposedly) you viewing
things you shouldn't with your TV (or whatever) that has an HDMI
connector.
On Wed, 06 Jan 2021 16:41:25 +0000, Theo wrote:
Maybe there are use cases where people want toDoing that would make the installation tidier if I wanted to glue the Pi enclosure to the back of the screen - provided that the screen
power their Pis from HDMI, I don't know.
can provide the wattage needed. Is that likely, bearing in mind that, if
I did that, I'd also want it to power a keyboard and mouse via the USB sockets on the Pi.
Chris Green <cl@isbd.net> wrote:
Andy Burns <usenet@andyburns.uk> wrote:
The Pi is the HDMI source, and the monitor is the HDMI sink, per theI've heard it said that the HDMI spec is a real can of worms.
spec the 5V power should be supplied from the Pi to the monitor, not the >> > reverse ...
This thread is just another thing that increases my dislike of HDMI.
It's exactly the same with VGA.
The purpose of this is for the computer to read the EDID ROM from the monitor. It supplies 5V to allow detection of the connected monitor even if it's turned off.
The monitor/KVM should not be emitting power on this rail.
On Wed, 06 Jan 2021 13:13:42 +0100
Axel Berger <Spam@Berger-Odenthal.De> wrote:
Exactly. And there is another thing. Originally video had to be
fast, for the eye needed at least 70 Hz not to see annnoying
flicker. Those
That number seems to have been creeping up all my life -
24FPS was once considered good enough for movie cameras.
On 06/01/2021 17:04, Martin Gregorie wrote:
On Wed, 06 Jan 2021 16:41:25 +0000, Theo wrote:
Maybe there are use cases where people want to power their Pis fromDoing that would make the installation tidier if I wanted to glue the
HDMI, I don't know.
Pi enclosure to the back of the screen - provided that the screen can
provide the wattage needed. Is that likely, bearing in mind that, if I
did that, I'd also want it to power a keyboard and mouse via the USB
sockets on the Pi.
HDMI will never power a Pi, way too thirsty.
Similar devices such as an Amazon Firestick have to have an external
PSU, as they require more power than even the TV's USB port can supply.
Note that if this does seem to work, you are probably overstressing your
TVs electronics, which will lead to premature failure.
For filming, but it was never displayed at that rate. In 50Hz countries, telecines and cinema projectors had a double shutter to display each
frame twice (though no interpolation)
and NTSC telecines repeated alternately 2/3 times to get it up to 60.
Axel Berger <Spam@Berger-Odenthal.De> wrote:
Exactly. And there is another thing. Originally video had to be fast,That number seems to have been creeping up all my life - 24FPS was
for the eye needed at least 70 Hz not to see annnoying flicker. Those
once considered good enough for movie cameras.
In more recent times 60Hz was said to be needed
for flicker free and now it's 70Hz I'm seeing and high end TVs are currently advertising 120Hz.
In comp.sys.raspberry-pi, Ahem A Rivet's Shot <steveo@eircom.net> wrote:
Axel Berger <Spam@Berger-Odenthal.De> wrote:
Exactly. And there is another thing. Originally video had to be fast,That number seems to have been creeping up all my life - 24FPS
for the eye needed at least 70 Hz not to see annnoying flicker. Those
was once considered good enough for movie cameras.
Possibly, but probably not. Thomas Edison believed 48 FPS was minimum
quality projection. Is that during your life?
Film was recorded at 24
FPS, yes, but projected so that each frame was shown two or three
times, 48 to 72 FPS.
On Wed, 6 Jan 2021 23:08:51 +0000 (UTC)
Eli the Bearded <*@eli.users.panix.com> wrote:
In comp.sys.raspberry-pi, Ahem A Rivet's Shot <steveo@eircom.net> wrote: >>> Axel Berger <Spam@Berger-Odenthal.De> wrote:
Exactly. And there is another thing. Originally video had to be fast,That number seems to have been creeping up all my life - 24FPS
for the eye needed at least 70 Hz not to see annnoying flicker. Those
was once considered good enough for movie cameras.
Possibly, but probably not. Thomas Edison believed 48 FPS was minimum
quality projection. Is that during your life?
No, but 50Hz interlaced monitors (stripped TVs really) are and
removing the interlace was considered enough to make it flicker free and "professional" circa 1980 - I sometimes turned the interlace back on and pushed the resolution up. In more recent times 60Hz was said to be needed
for flicker free and now it's 70Hz I'm seeing and high end TVs are currently advertising 120Hz.
Film was recorded at 24
FPS, yes, but projected so that each frame was shown two or three
times, 48 to 72 FPS.
Weren't domestic cine projectors 24 fps and considered good enough
for the use ?
Ahem A Rivet's Shot wrote:currently
In more recent times 60Hz was said to be needed
for flicker free and now it's 70Hz I'm seeing and high end TVs are
advertising 120Hz.
The way I remember it is, that one of the reason for white on black was
the lower sensitivity of the eye for flicker. The first monitors with a
white background were hailed as a huge improvement but they all -- both highly expesive ISA card monitor combos and the Atari -- needed 70 Hz to
be acceptable. 60 Hz was considered borderline for colour when white backgrounds were avoided.
No, but 50Hz interlaced monitors (stripped TVs really) are and
removing the interlace was considered enough to make it flicker free and "professional" circa 1980 - I sometimes turned the interlace back on and pushed the resolution up. In more recent times 60Hz was said to be needed
for flicker free and now it's 70Hz I'm seeing and high end TVs are currently advertising 120Hz.
Now with LCD, LCD/LED and OLED technologies the screen does not flicker
at the update rate. Panels used to have a 60Hz update rate to match US content (but would be fine for 50Hz), but active 3D drove the adoption
of 120Hz or greater panels, so alternate views could be shown at 60Hz.
3D has largely been dropped now, but 120Hz or greater panels still
exist, so they can either be driven at a higher frame rate by games
consoles, or additional intermediate frames are generated for lower
refresh rate content, in both cases to make animation smoother.
Weren't domestic cine projectors 24 fps and considered good enough
for the use ?
Weren't domestic cine projectors 24 fps and considered good enough
for the use ?
The Pi carried on being powered. After dismissing the possibility of sentient >self-powered computers taking over, I discovered that the volts were coming >via the HDMI port.
https://en.wikipedia.org/wiki/HDMI look at the pin-out... Pin 18 is intended to provide power for "active cables" https://www.hdmi.org/spec/hdmi2_1 https://www.hdmi.org/spec21sub/cablepower
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