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by error404
Sat Feb 04, 2012 8:01 am
Forum: General discussion
Topic: Can you power the Pi from GPIO?
Replies: 31
Views: 8139

Re: Can you power the Pi from GPIO?

<t>schlomo said: <br/> <br/> <br/> Thanks for the help error404 and plugwash. After playing around with WEBENCH, I've finally got a nice switched-mode power supply circuit designed. It has over 91% (!) efficiency and costs about $3.00. The problem: total (max) power dissipation is 700mW [when input ...
by error404
Sat Feb 04, 2012 3:11 am
Forum: Automation, sensing and robotics
Topic: 1wire using GPIO?
Replies: 8
Views: 17201

Re: 1wire using GPIO?

Using GPIO should be possible. See the previous thread on this topic...
by error404
Sat Feb 04, 2012 3:11 am
Forum: Other projects
Topic: Raspberry PI and Zigbee
Replies: 13
Views: 30126

Re: Raspberry PI and Zigbee

<r>Less than the ~$20 for an assembled XBee module? Not likely. The parts themselves are pretty cheap and there are Linux drivers for some of them, but you would need to build the module yourself. That's pretty non-trivial when most of the parts come in tiny QFN packages. Maybe some enterprising Chi...
by error404
Fri Feb 03, 2012 8:57 pm
Forum: General discussion
Topic: cheap i/o optoisolated board
Replies: 13
Views: 4821

Re: cheap i/o optoisolated board

<t>I was hoping my description would be good enough for you to design such yourself, it's pretty trivial for simple requirements. Are you after input or output? From/to what? How fast does it need to be?<br/> <br/> Your I/O board can be bidirectional, supporting this with optoisolation can be a bit ...
by error404
Fri Feb 03, 2012 2:29 am
Forum: General discussion
Topic: Can you power the Pi from GPIO?
Replies: 31
Views: 8139

Re: Can you power the Pi from GPIO?

<t>If you properly design an efficient regulator, there is no problem putting it on the board with everything else; after all this is what pretty much every bit of consumer electronics built in the last 10 years does.<br/> <br/> It's pretty hard to destroy a modern switchmode power supply; they pret...
by error404
Fri Feb 03, 2012 1:16 am
Forum: General discussion
Topic: Can you power the Pi from GPIO?
Replies: 31
Views: 8139

Re: Can you power the Pi from GPIO?

<t>DeliciousRaspberryCake said: <br/> <br/> It makes absolutely NO sense to pay $3.41 , $6.89 or even $15 for a single component, which might need several additional components and a circuit board to put them all on. (components are really expensive when bought as a single unit).<br/> <br/> <br/> <b...
by error404
Fri Feb 03, 2012 12:29 am
Forum: Other projects
Topic: Using 250GB Sata via USB. Possible?
Replies: 2
Views: 1348

Re: Using 250GB Sata via USB. Possible?

You don't need to boot from USB to make /home be stored there, just mount it that way.

But you can if you want, at least everything except the kernel. Put the kernel on the SD card with the correct options stored in it to mount the rootfs from USB.
by error404
Thu Feb 02, 2012 11:19 pm
Forum: General discussion
Topic: What do the status indicator LEDs indicate the status of?
Replies: 13
Views: 13841

Re: What do the status indicator LEDs indicate the status of?

<t>meltwater said:<br/> <br/> <br/> So does the 10M LED show that it's not 10Mbit or is it 10/100Mbit, since most appear to have it lit, or is it dual state/colour?<br/> <br/> <br/> <br/> The datasheet says that it is open-drain and driven low when operating at 100Mbps. Unless the foundation have wa...
by error404
Thu Feb 02, 2012 7:16 pm
Forum: General discussion
Topic: cheap i/o optoisolated board
Replies: 13
Views: 4821

Re: cheap i/o optoisolated board

<t>Optoisolators are very simple. If you"re using them as switches, you can basically model them as LEDs and drive them with a series current limiting resistor just like you would any other LED. Set the current from the datasheet"s LED current vs. collector current graph so that you have the necessa...
by error404
Thu Feb 02, 2012 2:40 am
Forum: Other projects
Topic: Suggestion: Tiny PCB for DC-anything to 5 V DC
Replies: 50
Views: 17932

Re: Suggestion: Tiny PCB for DC-anything to 5 V DC

<t>kme said:<br/> <br/> <br/> Looks interesting. As I already stated I know very little about electronics, but isn't 77% efficiency a bit disappointing?<br/> <br/> <br/> Pretty typical for a cost-optimized DC-DC converter I would say. It should be possible to get to 85+% for a reasonable cost and wi...
by error404
Wed Feb 01, 2012 11:14 pm
Forum: General discussion
Topic: New blog post from JamesH on the main page
Replies: 56
Views: 11766

Re: New blog post from JamesH on the main page

<t>It's hard to directly equate performance between different architectures with completely different design goals like that - but I'd be optimistic about software MPEG2 at DVD resolutions and bitrates. I remember doing it without much difficulty on a Celeron 400MHz back in the day, and as it's all ...
by error404
Wed Feb 01, 2012 11:11 pm
Forum: General discussion
Topic: compiling wifi drivers for arm
Replies: 5
Views: 3667

Re: compiling wifi drivers for arm

<t>As far as I can tell this device would be supported by the rtl8712 driver which is in the kernel mainline. Compiling it will be the same as compiling a mainline kernel module on any other Linux device.<br/> <br/> You probably won't have to though as I assume that the foundation will ship most ker...
by error404
Wed Feb 01, 2012 11:03 pm
Forum: Off topic discussion
Topic: What is the best program for windows to convert nearly any file to h.264 High Profile?
Replies: 15
Views: 3685

Re: What is the best program for windows to convert nearly any file to h.264 High Profile?

<t>ReCat said: <br/> <br/> <br/> I was first recommended FormatFactory by somebody who reviews a lot of software (writes articles), It's actually quite good, and Free. The UI is a bit confusing though. But i've used it many times.<br/> <br/> <br/> Except that, like almost all such 'freeware' program...
by error404
Wed Feb 01, 2012 9:58 pm
Forum: General discussion
Topic: Can you power the Pi from GPIO?
Replies: 31
Views: 8139

Re: Can you power the Pi from GPIO?

<t>In lieu of schematics, I am providing information that has been gleaned from various comments and subject to memory distortion.<br/> <br/> The GPIO +5V pin is connected after the polyfuse and TVS diode, but is the same power bus that drives the rest of the board. Thus it will work, but you probab...
by error404
Wed Feb 01, 2012 6:53 pm
Forum: Other projects
Topic: Programatically lock SD Card to hardware unit?
Replies: 28
Views: 7130

Re: Programatically lock SD Card to hardware unit?

<t>hedgehog said:<br/> <br/> <br/> Don't know how easy or effective this would be.<br/> <br/> <br/> <br/> Not very (for reasonable definitions of 'effective'), I don't think. Any kernel modification must be released under GPL, and due to the boot process of the BCM2835, it's trivial to replace the k...
by error404
Wed Feb 01, 2012 6:27 pm
Forum: General discussion
Topic: RTC
Replies: 36
Views: 16988

Re: RTC

<t>Crundy said: <br/> <br/> <br/> Speaking of which, does anyone know the BestTM way to update the system clock using a DS1338 module? I did find a C script a while back that did it using the DS1307 specification (which the DS1338 is apparently compatiable with) but I can't find it now. I was wonder...
by error404
Tue Jan 31, 2012 9:40 pm
Forum: Other projects
Topic: Cloud ftp
Replies: 11
Views: 3264

Re: Cloud ftp

<t>Other than the software stack, this is just a bog-standard SoC. So really all the magic, and the only interesting part, is in the software they've put together. Given that it appears to be completely closed source, I'm going to go with 'no'.<br/> <br/> That said, nothing this device does is parti...
by error404
Tue Jan 31, 2012 8:51 pm
Forum: Other projects
Topic: USB Arcade Controller
Replies: 15
Views: 7684

Re: USB Arcade Controller

<t>Pat said: <br/> <br/> This is not a joystick, just interface to arcade sticks of an arcade. I don't have good experience with keyboard hacks. This is a robust chip, and it's very easy to hook up your arcade sticks. just like ipac etc. This one is the cheapest of them all.<br/> <br/> The point was...
by error404
Tue Jan 31, 2012 5:41 pm
Forum: Other projects
Topic: USB Arcade Controller
Replies: 15
Views: 7684

Re: USB Arcade Controller

<t>Almost any joystick/controller should work fine. USB HID has a pretty robust way to describe these things, and Linux of course supports this. Unless the device is really weird (force feedback maybe?), everything should work out of the box.<br/> <br/> For more DIY-style projects, you can easily ca...
by error404
Tue Jan 31, 2012 5:38 pm
Forum: General discussion
Topic: Design choices behind the RPi
Replies: 35
Views: 7388

Re: Design choices behind the RPi

RaTTuS said:


http://www.xoreax.com/visual_studio.htm Incredibuild FTW - if your lucky



Or in context more useful, http://code.google.com/p/distcc/
by error404
Fri Jan 27, 2012 6:31 pm
Forum: Automation, sensing and robotics
Topic: Weather Satellite Receiving Station
Replies: 19
Views: 17661

Re: Weather Satellite Receiving Station

<r><URL url="http://www.wxtoimg.com/">http://www.wxtoimg.com/</URL> Though it is not open-source, there are Linux builds and you might convince the author to build it against ARM for you.<br/> <br/> Also, with sources:<br/> <br/> <URL url="http://atpdec.sourceforge.net/index.html">http://atpdec.sour...
by error404
Fri Jan 27, 2012 4:42 am
Forum: General discussion
Topic: ATX PSU as Power supply
Replies: 12
Views: 5226

Re: ATX PSU as Power supply

<t>If this two lead charging cable worked for you with a charger, I don't really have an answer for you. The ATX supply should work just as well, since any signalling stuff must be in the plug itself. Have you measured the voltage out of the charger that was working? I've heard of some devices wanti...
by error404
Fri Jan 27, 2012 2:45 am
Forum: General discussion
Topic: ATX PSU as Power supply
Replies: 12
Views: 5226

Re: ATX PSU as Power supply

<t>The USB spec requires that devices draw < 100mA from the bus before they negotiate for more from the host, so with no communication from the host, that's what it will do. Try shorting the data lines together. This is the standard way to signal to the peripheral that it is connected to a dumb powe...
by error404
Thu Jan 26, 2012 6:19 pm
Forum: General discussion
Topic: Rechargeble batteries suitable for the RPi?
Replies: 27
Views: 9620

Re: Rechargeble batteries suitable for the RPi?

<t>Garacesh said:<br/> <br/> <br/> Forgive my naivity, can a series of cells be recharged in-series, or would they need to be recharged separately? i.e. removing them from the Pi and plugging them into a typical mains charger? Or would I just be able to, say, plug a USB into the battery mount and in...
by error404
Thu Jan 26, 2012 6:09 pm
Forum: General discussion
Topic: Battery power
Replies: 68
Views: 25121

Re: Battery power

<t>mcookie said: <br/> <br/> <br/> I'm no electrical engineer, but will the classic "mintyboost" altoids thingy work?<br/> <br/> <br/> The DC-DC converter in the mintyboost is only rated for 600mA. It will probably work, at least most of the time, but it's a bit under-rated.<br/> <br/> As far as cap...

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