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by Johannes
Sat Sep 10, 2011 6:43 am
Forum: General discussion
Topic: Coburns take on powering the Raspberry Pi via batteries
Replies: 69
Views: 12990

Re: Coburns take on powering the Raspberry Pi via batteries

7.2V*10000mAh=7.2V*10Ah=72Wh. At 1W, that would give you 72Wh/1W=72 hours of battery life. At 0.25W almost two weeks (72Wh/0.25W=288h).
by Johannes
Wed Sep 07, 2011 9:20 am
Forum: General discussion
Topic: Second Ethernet port needed!
Replies: 32
Views: 17950

Re: Second Ethernet port needed!

<r>@anest:<br/> <URL url="http://wiki.openwrt.org/toh/st.....rt#tp-link">http://wiki.openwrt.org/toh/st.....rt#tp-link</URL><br/> <URL url="http://geizhals.at/eu/?cat=wla.....038;sort=p">http://geizhals.at/eu/?cat=wla.....038;sort=p</URL><br/> <br/> Those don't have as fast a CPU as the Raspi's, and...
by Johannes
Tue Sep 06, 2011 10:12 pm
Forum: General discussion
Topic: TrueCrypt, is it practical?
Replies: 5
Views: 4724

Re: TrueCrypt, is it practical?

Truecrypt can be compiled for ARM and it will work, but the Raspi doesn't have hardware AES support, so it will be slow (single-digit MB/s using all CPU time). Linux also supports full disk encryption out of the box. It's not going to be fast either though.
by Johannes
Tue Sep 06, 2011 9:58 pm
Forum: General discussion
Topic: Second Ethernet port needed!
Replies: 32
Views: 17950

Re: Second Ethernet port needed!

There are routers with 5 Ethernet ports, VLAN support and Wifi that can run OpenWRT and cost less than a Raspi. You can add a second USB-Ethernet port to a Raspi, but I think you should look into other options.
by Johannes
Sun Sep 04, 2011 4:56 pm
Forum: General discussion
Topic: Power supply
Replies: 93
Views: 15652

Re: Power supply

<t>I know that the USB standard isn't the technical limit, but many USB power supplies will not supply much more than 2.5W. They are after all designed to supply power to standard USB devices which aren't allowed to draw more than 2.5W. Again, I've seen USB power supplies which won't deliver even 2....
by Johannes
Sun Sep 04, 2011 3:02 pm
Forum: General discussion
Topic: Power supply
Replies: 93
Views: 15652

Re: Power supply

<t>Only phones which can exchange data with a computer through a wired connection (i.e. have a USB port) are required by the EU to support charging through USB. Many "feature phones" still come with non-USB chargers.<br/> <br/> Anyway, standard USB can only supply 2.5W (0.5A at 5V), which is enough ...
by Johannes
Tue Aug 30, 2011 11:21 pm
Forum: General discussion
Topic: Wake-on-LAN (WOL)
Replies: 12
Views: 22577

Re: Wake-on-LAN (WOL)

<r>What I mean is that there is no suspend mode. There's on and there's off. See abishur's comment here: <URL url="http://www.raspberrypi.org/?pa.....038;t=2.10">http://www.raspberrypi.org/?pa.....038;t=2.10</URL>. With no suspend mode and no soft power off, WOL is pointless. The CPU and the GPU wil...
by Johannes
Tue Aug 30, 2011 3:31 pm
Forum: General discussion
Topic: Wake-on-LAN (WOL)
Replies: 12
Views: 22577

Re: Wake-on-LAN (WOL)

There is no standby/hibernation mode. It's either without power or it's on. There is no power switch either. You plug in the power supply and it starts. To turn it off, you unplug it.
by Johannes
Tue Aug 30, 2011 1:38 pm
Forum: General discussion
Topic: Wake-on-LAN (WOL)
Replies: 12
Views: 22577

Re: Wake-on-LAN (WOL)

The Raspberry Pi is either on or not connected to the power supply. When it's on, you don't need to wake it up, and when it's not powered, nothing will wake it up.
by Johannes
Mon Aug 29, 2011 5:58 pm
Forum: General discussion
Topic: More RAM
Replies: 21
Views: 4680

Re: More RAM

<t>RAM is a limiting factor. If you've watched the video where Eben Upton talks at Bletchley Park, you must have noticed that the OS needs to be trimmed some more to fit into the Model A with just 128MB, so that there's still room for applications. Some people see this as an incentive for programmer...
by Johannes
Mon Aug 22, 2011 5:19 am
Forum: General discussion
Topic: What happen with USB key size(alpha prototype)?
Replies: 23
Views: 5054

Re: What happen with USB key size(alpha prototype)?

Advantages: HDMI and video out, price, H.264 decoding (and encoding) hardware, price, power consumption, price, digital I/O header, price, ...
by Johannes
Tue Aug 02, 2011 9:02 pm
Forum: General discussion
Topic: What have we missed?
Replies: 286
Views: 52367

Re: What have we missed?

FPGA. Seriously, if this is supposed to be an educational toy, reprogrammable logic would be an awesome addition.
by Johannes
Mon Aug 01, 2011 12:08 am
Forum: General discussion
Topic: Broadcom BCM2835 SoC
Replies: 196
Views: 35290

Re: Broadcom BCM2835 SoC

Any chance that the GPU can be used for accelerating AES through a standard kernel interface? Or is there a dedicated AES coprocessor?
by Johannes
Sun Jul 31, 2011 8:42 pm
Forum: General discussion
Topic: What have we missed?
Replies: 286
Views: 52367

Re: What have we missed?

<t>Is there a real-time clock on board?<br/> Is the power port protected against wrong polarity?<br/> Before anything else, more RAM would be useful, because it can't be added via USB or other interfaces.<br/> It would be great if you could get official Linux kernel support for your device early on....

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