RasPi power requirements overstated?

Go to any mobile phone shop.

Buy a phone charger with a micro USB connector. Any charger named brand that you're sure isn' a cheap clone.

Go home, be happy.

You didn't even try?

I power my Pi's off a combination of Laptops, PCs, cheap powered hubs and mobile phone chargers. Only the really nasy cheap chinese chargers which you know are rubbish anyway have real issues.

Do they have DIV inputs? If so HDMI to DVI adapters are cheap.

Failing that, Raspbian runs sshd at boot time, so you can ssh into it, then either use ssh forwarding, or run vnc on the Pi.

Gordon

Hi Gordon, I have just ordered a Pi from RS, and a cheap case and 4GB SD card from Ebay.

The initial plan is to use an image from:

The Pi will be stacked with 2 X PAP2 and a 10/100 switch, all 5v, so I'll try running them from a single PSU, I have a likely candidate here rated at 3.8A, but I will take some measurements.

Any anecdotes about the Pi running Asterisk would be useful. Also how long is an SD card expected to last in SSHD mode? I don't think it's what they were designed for, especially the 4GB ones that are £2.90 delivered from Hong Kong.

The Pi has 2 test point - TP! and TP2. They're connected to the 5V supply. As long as this is above about 4.75v you'll probably be OK. Don't overclock.

I've not tried. Not going to waste my time trying. Not interested. Others have reported it seems to work OK though.

Do yourself a favour and buy a real one from a reputable UK dealer. For the sake of a fiver more, is it worth the wory & hassle?

My original card, bought a year ago is still going strong. I have 5 Pi's and all my SD cards are working fine. I expect the SD card to last longer than the Pi.

Gordon

If only that were true.

The reality is that the Pi has a 700mA polyfuse on it's 5V input. The Pi itself needs between 300-400mA, leaving 300-400mA "spare" for the USBs, GPIO, etc., and in-practice if you get that close you're going to have issues.

(Oh, and if you have a Rev 1 Pi, then each USB has a 140mA polyfuse too)

You need a powered hub to do anything heavy-duty on the Pi.

Gordon

It's also the cables. I have a pile of micro USB cables including some allegedly 'genuine Nokia' (from ebay). Some of them just plain don't work with a Pi (including one '1A' power adaptor with integrated cable). I cut the end off a 'Nokia' cable to discover:

1. It has no shielding
2. The cores are absolutely tiny, having about 3 strands barely wider than a hair
3. The plastic sheath is extra fat to make up for the fact there's almost no copper in it
4. There's about a 1V voltage drop along this 1m cable between a power supply and a Pi.

I changed it for a Pi power cable bought from Farnell, and I can now run my Pi off almost any random USB socket I find (though without testing hungry USB peripherals). The same Pi power cable also makes my phone charge a lot faster from the same USB sockets - unsurprising if most of the power was lost in the cable!

Theo

X has it right, even if it does seem a bit odd until you think about it correctly. An X server provides display services and listens for clients to tell it to draw stuff on the screen. An X client contacts the X server and tells it to draw something on the screen.

We've had Asterisk and an early test version of our telephone reception management software running on a single Pi. We didn't make any serious load tests, but it is at least fine for one call at a time.

Greetings,

Jacob

On 09/04/2013 22:43, Theo Markettos wrote: []

I just got another power supply from ModMyPi, and note that it was labelled 5.25V 2A. I wonder what the loss in their supplied cable is? The RPi is now installed in the attic, so not easy to check. It's supporting two items on the USB ports - a Wi-Fi dongle (Netgear WG111v3) and a TV receiver dongle (R820T/RTL2832U). Hope my polyfuse doesn't blow! It's a very recent model-B RPi, though, and I recall some of the fuses are now bypassed.

On 10/04/2013 03:46, Robert Riches wrote: []

Maybe! Just like a PC running a "data base display server", getting data from clients running on a big UNIX box. Maybe not!

I just thought I would put the note in, though, as people coming at this for the first time, and seeing that Xming was a /server/, might think that I was recommending the wrong software. But it is a way of overcoming the requirements for a keyboard, mouse and display. I ran a graphical GPS program on the RPi and the display on the PC was quite adequate. I've not tried an X-server on my iPad, but I guess that would be as good.

So if I have Xming on my PC, what do I need to do to my Pi to make this magic happen?

deKay

Nothing special. You just run an X application on the Pi and it will display on your PC. You may have to setup the DISPLAY environment variable, but that's about it. X was designed as a "network aware" windowing system 25+ years ago...

Try to not use SSH as a transport mechanism though - the Pi is slow at encryption.

Gordon

On 10/04/2013 08:46, deKay wrote: []

E.g. see about 1/3 the way down this page:

with the section entitled "Pi SSH" about configuring the X display manager. I recall it being simpler than that, though, ans perhaps LXDE is what I used, mentioned eere:

OK, so lets just assume I have no idea what to do on the Pi side.

Um, what do I need to do on the Pi side to make this work? Or will it "just work" if I point Xming at it? (or rather, it at Xming).

I used to have this working on Windows 98 via a SuSE 7 box circa 2002 but it's lost knowledge now.

deKay

Excellent, thanks.

deKay

Off topic, but I've got a RTL2832U based device:

Is the driver for this now in the kernel or did you have to compile the driver?

Another Dave

On 10/04/2013 09:49, Another Dave wrote: []

I didn't need to recompile a somewhat minimal kernel. My step-by-step details are here:

so if your device is definitely RTL2832U-based you may be OK.

Whoops! No, it's a RTL2838U. Nothing to do with it. Sorry.

Another Dave

I read that there's no such device, and it's actually a 2832 wuth some strange identification. Most likely 2832 will work - it's certainly worth a try.

plug it into your TV?

I tried mine on an old TV with only RF in via an old VCR, for the composite to RF conversion I got a picture but no colour, I have not tried to diagnose the problem I havent even tried other programme sources.