On 31/12/16 14:08, Terry Coles wrote:
Hi,
I have a request for a loan of an externally powered USB Hub with at least 4
ports. If
anyone is in a position to loan me such a device, I'd be happy to collect and
return it within
a day or so.
I'm having a problem with the Wimborne Model Town hardware. I am using one of
these
with a Pi Zero:
https://www.modmypi.com/raspberry-pi/accessories/usb-hubs/hackable-naked-7-port-usb-hub-uk-5v-2.5a/?search=Hac[1]
It comes with a 2.5 A supply and is supposed to be able to back-power the Pi.
The trouble
is that it works when I power-up the Pi with only the mouse and keyboard
attached and
then attach the other peripherals one by one (three USB Audio Adaptors and a
WiFi
dongle). It crashes the Pi if I try to boot with said devices all attached.
I have run some tests on the PSU brick which comes with this and found that
with a 2 Ohm
load, I only get 2 A or so and the terminal voltage drops to 4.8 V. We could
power the Pi
separately, but that adds to the cost and needs a separate mains outlet.
However, before I ask for a refund, I'd like to remove this Hub from the
equation. I get a
similar problem when I use an unpowered hub, but I would expect that, since the
WiFi
Adaptor takes 240 mA and each of the Audio Adaptors takes another 170 mA (and
that's
steady state; the inrush current is going to be higher).
If I can prove that my peripherals aren't causing the problem, I'd be inclined
to go for one
of these:
https://thepihut.com/products/zero4u-4-port-usb-hub-for-raspberry-pi-zero[2]
I've got one Terry. It came from Novatech a couple of years ago and I
know that it powers the R-Pi, but not how much more.
Let me know and I can leave it available.
Cheers,
Peter
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