Pi Zeros for conference workshops

I'm involved in 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.

Reply to
D.M. Procida
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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.

I've done it - just takes time.

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

Reply to
Gordon Henderson

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,

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

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.

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.

Indeed,

-- mrr

Reply to
Morten Reistad

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.

Local conditions: there's be plenty of mains sockets, and also many people will already have micro-USB chargers for Android phones.

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

Thanks,

Daniele

Reply to
D.M. Procida

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

Can you recommend a reliable one?

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

Daniele

Reply to
D.M. Procida

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.

Reply to
Dom

The one I have was bought from Farnell.

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Gordon

Reply to
Gordon Henderson

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

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.

but I've always found startech are decent products, maybe they'd do a deal if it's for a 'good cause' ...

Reply to
Andy Burns

The KiwiTech adapter looks like a possibility for the Ethernet and USB connections:

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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

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 
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Reply to
Martin Gregorie

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?

Reply to
A. Dumas

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.

Reply to
Roger Bell_West

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

Reply to
Theo Markettos

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.)

That might well be a stumbling block. They are not trouble-free. The cheapest ones ( e.g.

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) 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

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.

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.

Reply to
Dave Farrance

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

Reply to
spuorgelgoog

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