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Pi Zeros for conference workshops

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  Pi Zeros for conference workshops real-not-anti-spam-address@apple-juice.co.uk (D.M. Procida) - 2015-11-29 10:11 +0000
    Re: Pi Zeros for conference workshops Gordon Henderson <gordon+usenet@drogon.net> - 2015-11-29 10:40 +0000
      Re: Pi Zeros for conference workshops real-not-anti-spam-address@apple-juice.co.uk (D.M. Procida) - 2015-11-29 11:42 +0000
        Re: Pi Zeros for conference workshops Gordon Henderson <gordon+usenet@drogon.net> - 2015-11-29 12:39 +0000
        Re: Pi Zeros for conference workshops Andy Burns <usenet.feb2014@adslpipe.co.uk> - 2015-11-29 13:19 +0000
        Re: Pi Zeros for conference workshops Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-29 14:03 +0000
    Re: Pi Zeros for conference workshops Morten Reistad <first@last.name.invalid> - 2015-11-29 12:06 +0100
      Re: Pi Zeros for conference workshops real-not-anti-spam-address@apple-juice.co.uk (D.M. Procida) - 2015-11-29 11:42 +0000
        Re: Pi Zeros for conference workshops "A. Dumas" <alexandre@dumas.fr.invalid> - 2015-11-29 15:14 +0100
        Re: Pi Zeros for conference workshops Theo Markettos <theom+news@chiark.greenend.org.uk> - 2015-11-29 15:39 +0000
      Re: Pi Zeros for conference workshops Dom <domafp@blueyonder.co.uk> - 2015-11-29 11:47 +0000
    Re: Pi Zeros for conference workshops Roger Bell_West <roger+csrp201511@nospam.firedrake.org> - 2015-11-29 14:53 +0000
    Re: Pi Zeros for conference workshops Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-11-30 10:28 +0000
    Re: Pi Zeros for conference workshops spuorgelgoog@gowanhill.com - 2015-11-30 13:10 -0800

#10036 — Pi Zeros for conference workshops

I'm involved in <http://na.pycon.org> in 2016.

One issue we had at 2015's event is that almost no-one had access to a
machine well-suited to the workshops. Even the University's lab machines
were running Windows and needed a lot of basic installation.

To shortcut the hours we spent installing (and troubleshooting)
software, I'm trying to work out if we could afford to put together a
conference workshop machine, or rather something like 50 of them, built
around a Pi Zero:

* Pi Zero
* 8GB SD card
* VGA adaptor (VGA displays will be readily available)
* USB hub for keyboard, mouse and network adaptor
* USB-Ethernet adaptor
* pre-installed software (Git, Mercurial, Pillow, virtualenv, all 
  Python/C dependencies, etc) 

Does anyone know whether a powered USB hub would be required for all
those devices? How trouble-free are VGA adaptors?

Any experiences writing 50 SD cards with an updated image?

If we can do with unpowered hubs, that much better. 

PSUs will be sourced locally, for the Namibian mains sockets.

At the end of the conference we can leave the Pis in the hands of the
many students who will be there. All the students who actually owned
computers had ancient Windows XP (or older) laptops that were far from
ideal for what we were doing in the workshops.

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#10037

In article <1men7m0.cshrvs1vzq1h1N%real-not-anti-spam-address@apple-juice.co.uk>,
D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk> wrote:
>I'm involved in <http://na.pycon.org> in 2016.
>
>One issue we had at 2015's event is that almost no-one had access to a
>machine well-suited to the workshops. Even the University's lab machines
>were running Windows and needed a lot of basic installation.
>
>To shortcut the hours we spent installing (and troubleshooting)
>software, I'm trying to work out if we could afford to put together a
>conference workshop machine, or rather something like 50 of them, built
>around a Pi Zero:
>
>* Pi Zero
>* 8GB SD card
>* VGA adaptor (VGA displays will be readily available)
>* USB hub for keyboard, mouse and network adaptor
>* USB-Ethernet adaptor
>* pre-installed software (Git, Mercurial, Pillow, virtualenv, all 
>  Python/C dependencies, etc) 
>
>Does anyone know whether a powered USB hub would be required for all
>those devices? How trouble-free are VGA adaptors?

With the Pi Zero:

Since you need keyboard and mouse as well as Ethernet then you'll need
a USB hub of some sorts - so I'd suggest using powered hubs. the Pi Zero
will back-power via the USB data port without any issues at all, so just
one PSU (for the hub) per Pi.

>Any experiences writing 50 SD cards with an updated image?

I've done it - just takes time.

>If we can do with unpowered hubs, that much better. 
>
>PSUs will be sourced locally, for the Namibian mains sockets.

You either power the Pi which powers the hubs, or power the hubs which
powers the Pi. I think it might be easier to use powered hubs, but
local conditions might dictate otherwise.

As far as I can tell, the Pi Zero has no special power input protection
like the v2 or the B+.

I've also read that the HDMI port has no limitation on the 5v power too
but I've not had any issues with the hdmi -> vga adapters I've used in
the past. There is a 2nd type of VGA adapter which goes onto the GPIO
port, but I think that requires soldering - and you'll need to solder
on the GPIO pins anyway if you want to go down that route.

Good luck!

Gordon

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#10040

Gordon Henderson <gordon+usenet@drogon.net> wrote:

> >To shortcut the hours we spent installing (and troubleshooting)
> >software, I'm trying to work out if we could afford to put together a
> >conference workshop machine, or rather something like 50 of them, built
> >around a Pi Zero:
> >
> >* Pi Zero
> >* 8GB SD card
> >* VGA adaptor (VGA displays will be readily available)
> >* USB hub for keyboard, mouse and network adaptor
> >* USB-Ethernet adaptor
> >* pre-installed software (Git, Mercurial, Pillow, virtualenv, all 
> >  Python/C dependencies, etc) 
> >
> >Does anyone know whether a powered USB hub would be required for all
> >those devices? How trouble-free are VGA adaptors?
> 
> With the Pi Zero:
> 
> Since you need keyboard and mouse as well as Ethernet then you'll need
> a USB hub of some sorts - so I'd suggest using powered hubs. the Pi Zero
> will back-power via the USB data port without any issues at all, so just
> one PSU (for the hub) per Pi.

OK, I hadn't considered back-powering.

If a USB hub can power all the devices *and* the Pi without complaint,
that would look like a good way to go.

> You either power the Pi which powers the hubs, or power the hubs which
> powers the Pi. I think it might be easier to use powered hubs, but
> local conditions might dictate otherwise.

Local conditions: there's be plenty of mains sockets, and also many
people will already have micro-USB chargers for Android phones.
 
> As far as I can tell, the Pi Zero has no special power input protection
> like the v2 or the B+.
> 
> I've also read that the HDMI port has no limitation on the 5v power too
> but I've not had any issues with the hdmi -> vga adapters I've used in
> the past. There is a 2nd type of VGA adapter which goes onto the GPIO
> port, but I think that requires soldering - and you'll need to solder
> on the GPIO pins anyway if you want to go down that route.

No thanks to soldering 50 devices... but can you recommend a brand or
souorce for HDMI > VGA adaptors?

Thanks,

Daniele

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#10043

In article <1menbye.1tpayz0ifeyuuN%real-not-anti-spam-address@apple-juice.co.uk>,
D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk> wrote:
>Gordon Henderson <gordon+usenet@drogon.net> wrote:
>> I've also read that the HDMI port has no limitation on the 5v power too
>> but I've not had any issues with the hdmi -> vga adapters I've used in
>> the past. There is a 2nd type of VGA adapter which goes onto the GPIO
>> port, but I think that requires soldering - and you'll need to solder
>> on the GPIO pins anyway if you want to go down that route.
>
>No thanks to soldering 50 devices... but can you recommend a brand or
>souorce for HDMI > VGA adaptors?

The one I have was bought from Farnell.

http://cpc.farnell.com/element14/piview/hdmi-to-vga-adapter-for-raspberry/dp/SC12760

Gordon

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#10044

D.M. Procida wrote:

> If a USB hub can power all the devices *and* the Pi without complaint,
> that would look like a good way to go.

How about using a USB docking station? e.g.

<http://startech.com/uk/~USBVGADOCK2>

If it provides enough power over USB for the Pi (supplied adapter is 
3A@5V) it will also give you the VGA and Ethernet interfaces, ports to 
plug keyboard and mouse, and give you sound in/out too.

Can be had from Amazon for £53, you may be able to find cheaper devices, 
but I've always found startech are decent products, maybe they'd do a 
deal if it's for a 'good cause' ...

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#10046

On Sun, 29 Nov 2015 11:42:52 +0000, D.M. Procida wrote:

> If a USB hub can power all the devices *and* the Pi without complaint,
> that would look like a good way to go.
>
The KiwiTech adapter looks like a possibility for the Ethernet and USB
connections: 

http://www.amazon.co.uk/KiwiTek%C2%AE-Arrivals-Ethernet-Microsoft-18-
month/dp/B00Z4LW08A/ref=sr_1_9?
ie=UTF8&qid=1448804697&sr=8-9&keywords=ethernet+micro-usb+adapter

At least the price is sort of OK at £15.99, though it does need an 
external 5v supply. There are cheaper ethernet+usb adapters, but anything 
much cheaper starts to get lower approval ratings and still needs an 
external PSU.

You can get individual 2A PSUs for under a fiver. Alternatively, you can 
find 10-12A 5v PSUs for £10-£12. These are designed for 5V LED lighting 
but each one can run several RPIs, which matches the price of the cheaper 
individual PSUs and will save a bit on multi-socket extensions.


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |

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#10038

In article <1men7m0.cshrvs1vzq1h1N%real-not-anti-spam-address@apple-juice.co.uk>,
D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk> wrote:
>I'm involved in <http://na.pycon.org> in 2016.
>
>One issue we had at 2015's event is that almost no-one had access to a
>machine well-suited to the workshops. Even the University's lab machines
>were running Windows and needed a lot of basic installation.
>
>To shortcut the hours we spent installing (and troubleshooting)
>software, I'm trying to work out if we could afford to put together a
>conference workshop machine, or rather something like 50 of them, built
>around a Pi Zero:
>
>* Pi Zero
>* 8GB SD card
>* VGA adaptor (VGA displays will be readily available)
>* USB hub for keyboard, mouse and network adaptor
>* USB-Ethernet adaptor
>* pre-installed software (Git, Mercurial, Pillow, virtualenv, all 
>  Python/C dependencies, etc) 

You may want to use a pi-b, since it has a few usb ports and ethernet, this
may be worthwhile; since you may save the usb hubs. OTOH you may use the hub
to power the pi itself.

I maintain a network of these (pi-b's) by swapping sd cards made in a master.
The master is just another pi-b with a usb-to-sd card adapter, and i use plain
DD to make the cards, 

>Does anyone know whether a powered USB hub would be required for all
>those devices? How trouble-free are VGA adaptors?

They vary a lot. Resolutions supported is especially an issue.

>Any experiences writing 50 SD cards with an updated image?

Other than it taking a bit of time it is an easy task, Just see
to it that they are identical in size, or take measures to do a
partition resize; or just use the smallest card as the master.

>If we can do with unpowered hubs, that much better. 

The pi-b has two USB slots and ethernet, and is discounted now
to $25. I doubt you can get a poweres hub and usb-to-ethernet
much cheaper than $20, Besides, it is readily available now.

Otherwise, use the USB hub to power the pi-0, so you save one
power supply.

>PSUs will be sourced locally, for the Namibian mains sockets.
>
>At the end of the conference we can leave the Pis in the hands of the
>many students who will be there. All the students who actually owned
>computers had ancient Windows XP (or older) laptops that were far from
>ideal for what we were doing in the workshops.

Indeed,

-- mrr

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#10041

Morten Reistad <first@last.name.invalid> wrote:

> >To shortcut the hours we spent installing (and troubleshooting)
> >software, I'm trying to work out if we could afford to put together a
> >conference workshop machine, or rather something like 50 of them, built
> >around a Pi Zero:
> >
> >* Pi Zero
> >* 8GB SD card
> >* VGA adaptor (VGA displays will be readily available)
> >* USB hub for keyboard, mouse and network adaptor
> >* USB-Ethernet adaptor
> >* pre-installed software (Git, Mercurial, Pillow, virtualenv, all 
> >  Python/C dependencies, etc) 
> 
> You may want to use a pi-b, since it has a few usb ports and ethernet, this
> may be worthwhile; since you may save the usb hubs. OTOH you may use the hub
> to power the pi itself.

I think the price is key here, hence the Pi Zero. We'll do whatever
works out the cheapest, and works.

> They vary a lot. Resolutions supported is especially an issue.

Can you recommend a reliable one?

> >If we can do with unpowered hubs, that much better. 
> 
> The pi-b has two USB slots and ethernet, and is discounted now
> to $25. I doubt you can get a poweres hub and usb-to-ethernet
> much cheaper than $20, Besides, it is readily available now.

Thanks, we're trying to work all this out.

Daniele

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#10047

On 29/11/2015 12:42, D.M. Procida wrote:
> I think the price is key here, hence the Pi Zero. We'll do whatever
> works out the cheapest, and works.

Then remember to also factor in a mini-HDMI to HDMI adapter before you 
can attach your HDMI to VGA adapter. But isn't DVI more common than VGA 
now, even on older equipment up to a point?

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#10050

D.M. Procida <real-not-anti-spam-address@apple-juice.co.uk> wrote:
> Morten Reistad <first@last.name.invalid> wrote:
> 
> > You may want to use a pi-b, since it has a few usb ports and ethernet, this
> > may be worthwhile; since you may save the usb hubs. OTOH you may use the hub
> > to power the pi itself.
> 
> I think the price is key here, hence the Pi Zero. We'll do whatever
> works out the cheapest, and works.

Depending on your timelines, I'd be tempted to wait for a little while.

The Pi Zero has mini HDMI, USB and power all on the same side, so I wouldn't
be surprised if someone comes out with a 'docking station' that does all of
this in one go.  That would be the neatest solution, assuming pricing is
affordable.  It would make a lot of sense given that the Pi A/B are
something of a pain to panel mount because of their connectors on
all sides, so the market is bigger than those who just want a cheap Pi.

If you want to do it with commodity parts, you'll probably end up with
several bits - VGA adaptor, possibly mini-full HDMI adaptor (but you can
probably find a VGA dongle with mini HDMI in), USB OTG cable, USB hub,
ethernet.  Which is why you may well save on a combined unit.

Theo

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#10042

On 29/11/15 11:06, Morten Reistad wrote:
> The pi-b has two USB slots and ethernet, and is discounted now
> to $25. I doubt you can get a poweres hub and usb-to-ethernet
> much cheaper than $20, Besides, it is readily available now.

The B+ is also discounted now and has four USB ports and better power 
management. You shouldn't need a USB hub at all with the B+.

For VGA, as Gordon mentioned, there is the alternative "Gert VGA666" 
adaptor which connects to the GPIO pins. It works well and is supported 
natively by the hardware and firmware. However it does come in kit form 
and will require some basic soldering skills (all standard through-hole 
components, no fiddly surface mount stuff). It also uses almost all of 
the GPIO pins.

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#10049

On 2015-11-29, D.M. Procida wrote:
>How trouble-free are VGA adaptors?

One thing to watch for - some cheap "HDMI to VGA" adaptors are passive
devices that only carry a pre-existing analogue VGA signal rather than
actually converting digital to analogue. This isn't the problem it is
with DVI to VGA, where analogue video is actually an optional part of
the standard rather than a non-standard extension, but just make sure
you get a proper one.

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#10057

real-not-anti-spam-address@apple-juice.co.uk (D.M. Procida) wrote:

> ... something like 50 of them, built around a Pi Zero:

That might be a bit of a false economy given that the peripherals will
have a cost that's a large multiple of the CPU board. The GUI desktop of
the original Pi (and therefore the Pi zero, I presume) is slow and
unresponsive. I'd suggest a Pi2 based solution as a minimum. (You
wouldn't want to give *those* away afterwards, but those are also of
limited use to students unless they already had all the necessary
peripherals.)

>Does anyone know whether a powered USB hub would be required for all
>those devices? How trouble-free are VGA adaptors?

That might well be a stumbling block. They are not trouble-free. The
cheapest ones ( e.g. http://www.ebay.co.uk/itm/131598464864 ) often
don't detect the VGA resolution and pass it back to the HDMI, so you'd
have to manually configure the Pi's config files before you could
display something on the screen, which is complex and totally defeats
the idea of plug-and-play. Also, the cheaper ones consume about 200mA
from the HDMI, and there are reports of them burning out the Pi.  There
are better reports of the more expensive adaptors ~£15, but beware that
even those will only work with a limited set of native display
resolutions, which might not match your VGA monitors.

Second-hand non-widescreen DVI monitors are usually very cheap, but are
difficult to obtain in bulk at short notice.  HDMI->DVI adaptors are
fine because they are passive directly-wired adaptors (but note that
they do not pass audio). That's a *much* better solution, if it is
possible for you.

>Any experiences writing 50 SD cards with an updated image?

That shouldn't be a problem. Configure one of the Pis so that it's as
you want it, then copy its SD-card to an image via a USB adaptor, then
write the image to the other SD cards. It's just very time consuming.
You'll find guides for SD-Card copying if you Google for them.

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#10058

On Sunday, 29 November 2015 10:12:00 UTC, D.M. Procida  wrote:
> One issue we had at 2015's event is that almost no-one had access to a
> machine well-suited to the workshops. Even the University's lab machines
> were running Windows and needed a lot of basic installation.

Alternative solution if you have computer labs available - take your own server with your own software configuration and turn the lab machines into thin clients, preferably by USB booting. 

Sell USB sticks with the thin client boot on, which delegates can also save stuff on and take home with them, or put the boot disk image online before the conference so people can arrive with their own sticks already set up.

Apart from possibly enabling USB boot and changing boot device order, this would need no changes to the lab machines before the event, and no changes after unless the lab want to remove USB boot capability for security reasons. 

Owain

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