On 13/09/2020 17:30, NY wrote:

I have an Atolla powered USB hub

https://www.amazon.co.uk/gp/product/B07B2HJG8P/ref=ppx_yo_dt_b_asin_title_o03_s 01

which I bought to power a spinning HDD that I plugged into my Pi 3B+.

I'm now using it in my Pi 4B. If the Pi is rebooted without shutdown and power-off/on, it boots fine. However if it is shutdown and then the
power is
removed and replaced (whether that is immediately or half an hour later)
the
Pi refuses to boot: the green LED does not come on and nothing appears on either HDMI output. If it is in that state and I unplug the hub, booting continues immediately, even if the hub is replaced immediately after being removed.

Has anyone some across this incompatibility? It's a bit of a bummer because it means the Pi will not auto-start in the even of a power-cut - unless
I am
present to remove/replace the hub.

It is related to the hub rather than what is plugged into it. It happens
even if the HDD and other devices are removed from it. Removing the
power to
the hub is sufficient to allow booting: maybe I need some means of making
the mains to the hub delay coming on for a few seconds after power it supplied to the Pi!

I'm wondering whether to buy a different make of hub, or whether I may find that this is affected in the same way.

Does anyone know of a make of powered USB3 hub which is known to work
with the Pi 4 after power-cycle?

This is separate to the /etc/fstab auto-mount problem that I posted about yesterday. In that case, the Pi would *start* to boot and then fail at
mount
time; in this case there is no sign that the Pi is even beginning to boot.

Known problem:

https://www.raspberrypi.org/forums/viewtopic.php?t=244900

One fix is to snip the red wire in the cable between the hub and the Pi.
--
Dave

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"Dave" <dave@cyw.uklinux.net> wrote in message news:rjlj9s$1bd$1@dont-email.me...

Does anyone know of a make of powered USB3 hub which is known to work
with the Pi 4 after power-cycle?

Known problem:

https://www.raspberrypi.org/forums/viewtopic.php?t=244900

One fix is to snip the red wire in the cable between the hub and the Pi.

I've read some reports that this doesn't always fix the problem, though from
my understanding of the problem (hub wrongly continues to supply power to Pi when Pi's own PSU is unpowered) it *ought* to fix it.

Does anyone know whether the list https://elinux.org/RPi_Powered_USB_Hubs is relevant to the Pi 4? I can't find a revision date.

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NY <me@privacy.invalid> wrote:

Does anyone know whether the list https://elinux.org/RPi_Powered_USB_Hubs is relevant to the Pi 4? I can't find a revision date.

Probably not: https://elinux.org/index.php?title=RPi_Powered_USB_Hubs&action=history

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"Theo" <theom+news@chiark.greenend.org.uk> wrote in message news:7hl*zz61x@news.chiark.greenend.org.uk...

NY <me@privacy.invalid> wrote:

Does anyone know whether the list https://elinux.org/RPi_Powered_USB_Hubs
is
relevant to the Pi 4? I can't find a revision date.

Probably not: https://elinux.org/index.php?title=RPi_Powered_USB_Hubs&action=history

Ah! Forgot to check that history.

Incidentally, Dave's suggestion of cutting the red wire (presumably +5V)
didn't work. I cut the red wire of a short male USB A - female USB A lead
and inserted it between the hub and the Pi. But the Pi still fails to boot
from power-off state if the hub is powered-up (irrespective of whether
anything is plugged into the hub).

Any other suggestions? Pi Hut sell a 7-port powered hub which is said not to backfeed power from hub to Pi, but it's only USB 2, and I'll like to take
full advantage of the Pi's USB3 ports if I have several discs, some of them USB3, all connected to the Pi through the hub.

Is it a problem that the Pi 4 is more susceptible to than the 3B+? Because I never encountered it with that.

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"Chris Elvidge" <chris@mshome.net> wrote in message news:rjndmk$et8$1@dont-email.me...

On 13/09/2020 05:30 pm, NY wrote:

Has anyone some across this incompatibility? It's a bit of a bummer
because
it means the Pi will not auto-start in the even of a power-cut - unless I
am
present to remove/replace the hub.

Yes, I've seen this but I stopped using USB hubs so can't test.
"In the event of a power-cut." Won't the hub be powered down as well as
the Pi? What happens if you shut the Pi down (shutdown -h now) and then remove/reconnect power to the hub, leaving all the other connections as
they were?

I've yet to test a simulated power cut: shutdown Pi, then turn off both Pi
and hub, turning them on simultaneously as if power had been restored after
a power cut. I imagine it will be a boundary condition: depending on how the
Pi reacts, the fact that the hub has power *as* the Pi boots will either
just work or else just fail. I'll report back on this thread when I've had chance to try a simulated power cut.

We went through a phase last year when there were frequent brief
interruptions to our village's supply because trees were shorting high
voltage lines somewhere in the area, tripping circuit breakers. Hopefully that's been resolved now, but it will always be a weak point if a power cut (when we're not at home) puts the Pi into a state where it will not reboot, given that I will be using it as a PVR for recording TV. If I can't resolve
it by getting a hub that works OK with the Pi 4, I may have to go back to
using my older Pi 3 again for doing that job - luckily everything is still configured on the 3. I suppose I could buy an external hard disc with its
own power supply, and dispense with the hub - as long as the disc itself doesn't prevent the Pi booting if disc and Pi PSUs both turn on at the same time.

The fact that a lead with the red 5V wire cut still experiences the problem suggests that back-feeding of power from hub to Pi *may* be a red herring.
I'm wondering whether it's rogue negotiations on the data lines as the
devices start up. Goodness knows how that can be resolved.

Are there devices which delay the mains being turned on by a few seconds if
I need the Pi to be turned on just before the hub?

--- SoupGate-Win32 v1.05
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On 13/09/2020 05:30 pm, NY wrote:

Has anyone some across this incompatibility? It's a bit of a bummer because it means the Pi will not auto-start in the even of a power-cut - unless
I am
present to remove/replace the hub.

Yes, I've seen this but I stopped using USB hubs so can't test.
"In the event of a power-cut." Won't the hub be powered down as well as
the Pi? What happens if you shut the Pi down (shutdown -h now) and then remove/reconnect power to the hub, leaving all the other connections as
they were?


--

Chris Elvidge, England

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On 14/09/2020 11:19, NY wrote:

The fact that a lead with the red 5V wire cut still experiences the
problem suggests that back-feeding of power from hub to Pi *may* be a
red herring. I'm wondering whether it's rogue negotiations on the data
lines as the devices start up. Goodness knows how that can be resolved.

There's a post on the forum thread I mentioned which states that the Pi
must have all its power buses below 200mV in order to fully reset. It
seems that power from the hub's USB data lines is leaking onto the Pi
and causing the problem.
--
Dave

--- SoupGate-Win32 v1.05
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In article <rjng4a$tsi$1@dont-email.me>, NY <me@privacy.invalid> wrote:

Are there devices which delay the mains being turned on by a few seconds if
I need the Pi to be turned on just before the hub?

Yes, whether they will work with low-draw devices like a Pi? I can't say.

There are power-saving mains switches/extension strips where you are
intended to plug the "computer" into the master port, and other
peripherals into the "peripheral" port(s). When the computer powers on,
the peripherals come on a couple of seconds later. When the computer
powers down, peripherals go off after a short delay.

The snag is, the one I have (free from eon/n-power?) continues to calibrate itself based on current draw, not just a simple "0ma or something more" cutoff.

So when used with power tools (to activate an always-on vacuum cleaner
for auto-dust collection), it can sometimes get confused as the load goes
from zero, to "idling saw" (at which point it turns on), to "saw is cutting wood for 10 seconds" then back to "idling saw": and switches off, because
the load dropped noticeably.

Of course, I don't want it to shut off while the saw is still running :)
--
--------------------------------------+------------------------------------ Mike Brown: mjb[-at-]signal11.org.uk | http://www.signal11.org.uk

--- SoupGate-Win32 v1.05
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On 13/09/2020 17:30, NY wrote:

I have an Atolla powered USB hub

https://www.amazon.co.uk/gp/product/B07B2HJG8P/ref=ppx_yo_dt_b_asin_title_o03_s 01

which I bought to power a spinning HDD that I plugged into my Pi 3B+.

I'm now using it in my Pi 4B. If the Pi is rebooted without shutdown and power-off/on, it boots fine. However if it is shutdown and then the
power is
removed and replaced (whether that is immediately or half an hour later)
the
Pi refuses to boot: the green LED does not come on and nothing appears on either HDMI output. If it is in that state and I unplug the hub, booting continues immediately, even if the hub is replaced immediately after being removed.

Has anyone some across this incompatibility? It's a bit of a bummer because it means the Pi will not auto-start in the even of a power-cut - unless
I am
present to remove/replace the hub.

It is related to the hub rather than what is plugged into it. It happens
even if the HDD and other devices are removed from it. Removing the
power to
the hub is sufficient to allow booting: maybe I need some means of making
the mains to the hub delay coming on for a few seconds after power it supplied to the Pi!

I'm wondering whether to buy a different make of hub, or whether I may find that this is affected in the same way.

Does anyone know of a make of powered USB3 hub which is known to work
with the Pi 4 after power-cycle?

This is separate to the /etc/fstab auto-mount problem that I posted about yesterday. In that case, the Pi would *start* to boot and then fail at
mount
time; in this case there is no sign that the Pi is even beginning to boot.

I had similar problems. At some point in booting the pi powers up the
usb devices and it didn't seem to like the hub being already powered at
that point.
I made a usb lead with just the power lines connected. This was
connected to a spare usb socket on the Pi and was used to power a relay.
The relay switched on when the Pi powered up the usb lines and power to
the hub was routed through the relay contacts so that it powered up at
the same time. This worked OK.
The relay must be able to work on 5 volts and the one I used pulled
about 30mA.
I didn't try it but perhaps a logic level mosfet could replace the relay?

--- SoupGate-Win32 v1.05
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On 15/09/2020 10:16, js wrote:

I had similar problems. At some point in booting the pi powers up the
usb devices and it didn't seem to like the hub being already powered at
that point.
I made a usb lead with just the power lines connected. This was
connected to a spare usb socket on the Pi and was used to power a relay.
The relay switched on when the Pi powered up the usb lines and power to
the hub was routed through the relay contacts so that it powered up at
the same time. This worked OK.
The relay must be able to work on 5 volts and the one I used pulled
about 30mA.
I didn't try it but perhaps a logic level mosfet could replace the relay?

Should have mentioned that I had cut the red wire in the hub usb lead so
that it could not backfeed the Pi.

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