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by sylvan
Thu Apr 23, 2015 6:32 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C to 16x2 LCD converter - voltage and RPi connection.
Replies: 19
Views: 8149

Re: I2C to 16x2 LCD converter - voltage and RPi connection.

I have a 20x4 display with what appears to be the same I2C adaptor originally pictured, using a PCF8574 I2C to 8-bit parallel chip. My adaptor (because of the LCD) requires 5v. With the pullups on the I2C lines (clock and data are pulled toward 5v) it is not safe to connect those lines to the Raspbe...
by sylvan
Mon Feb 09, 2015 1:00 am
Forum: Troubleshooting
Topic: Why is the PI2 camera-shy ?
Replies: 162
Views: 266170

Re: Why is the PI2 camera-shy ?

Conclusion: High likelihood U16 is exhibiting optical sensitivity to near infrared. Possible the intensity of a TV remote IR LED is not strong enough to freeze Raspberry Pi 2. I'd say likely. A TV remote IR LED is a minuscule fraction of the intensity of even the weak LASER in a pointer, and in add...
by sylvan
Sun Feb 08, 2015 11:52 pm
Forum: Troubleshooting
Topic: Why is the PI2 camera-shy ?
Replies: 162
Views: 266170

Re: Why is the PI2 camera-shy ?

Yes, and doing tape, foil, maybe more tape, seems to be overly complicating this problem. * problem observed with xenon flash * problem not observed with LED flash * problem observed with red LASER diode * problem prevented by thoroughly covering U16 with blu-tack * minimal covering around U16 elimi...
by sylvan
Wed Jan 25, 2012 6:45 pm
Forum: Other projects
Topic: PiCard - GUI SD Preparation Tool
Replies: 268
Views: 73456

Re: PiCard - GUI SD Preparation Tool

<t>jojopi said:<br/> <br/> <br/> Even if the device size were stored in the MBR and Linux did not ignore it, it would still be perfectly safe to dd a 4GB image onto an 8GB card, say, and optionally resize it later.<br/> <br/> <br/> <br/> Maybe.  Or maybe not.  As I posted (probably while you were po...
by sylvan
Wed Jan 25, 2012 6:43 pm
Forum: Other projects
Topic: PiCard - GUI SD Preparation Tool
Replies: 268
Views: 73456

Re: PiCard - GUI SD Preparation Tool

<t>jojopi said: <br/> <br/> It already has to get the device size from the hardware in order to support the case where you put a file system on the whole disk with no partition table ("superfloppy" format).<br/> Well that's not really correct either.  Look at a volume boot record (the first sector o...
by sylvan
Wed Jan 25, 2012 6:41 pm
Forum: Other projects
Topic: PiCard - GUI SD Preparation Tool
Replies: 268
Views: 73456

Re: PiCard - GUI SD Preparation Tool

<r>jojopi said:<br/> <br/> <br/> The device size is not stored in the partition table.  See the layout at <URL url="http://en.wikipedia.org/wiki/M.....oot_record">http://en.wikipedia.org/wiki/M.....oot_record</URL><br/> <br/> Even if the device size were stored in the MBR, Linux would ignore it.  It...
by sylvan
Wed Jan 25, 2012 6:25 pm
Forum: Other projects
Topic: PiCard - GUI SD Preparation Tool
Replies: 268
Views: 73456

Re: PiCard - GUI SD Preparation Tool

<t>davidgoodenough said: <br/> <br/> <br/> sylvan said:<br/> <br/> <br/> Is that before or after the kernel reads the incorrect size from the partition table?<br/> <br/> <br/> You would do it on the host machine where you are creating the SD card before you boot.  If you boot with the wrong size, th...
by sylvan
Wed Jan 25, 2012 5:37 pm
Forum: Other projects
Topic: PiCard - GUI SD Preparation Tool
Replies: 268
Views: 73456

Re: PiCard - GUI SD Preparation Tool

<t>davidgoodenough said: <br/> <br/> <br/> sylvan said:<br/> <br/> <br/> except for one thing...   the size of the device is encoded in the partition table (typically the first sector) and if you overwrite that, things get confusing later.<br/> <br/> <br/> Actually you can use any of the parted fami...
by sylvan
Wed Jan 25, 2012 5:32 pm
Forum: Other projects
Topic: PiCard - GUI SD Preparation Tool
Replies: 268
Views: 73456

Re: PiCard - GUI SD Preparation Tool

<t>Liam Fraser said:<br/> <br/> <br/> The size of the actual device is not stored in the partition table...<br/> <br/> <br/> You are wrong about that.<br/> <br/> The table stores the size of the device and the size of each partition.  The table also stores the CHS geometry, but that is mostly irrele...
by sylvan
Wed Jan 25, 2012 4:57 pm
Forum: Other projects
Topic: PiCard - GUI SD Preparation Tool
Replies: 268
Views: 73456

Re: PiCard - GUI SD Preparation Tool

<t>khannie said: <br/> <br/> <br/> For linux users I think dd would work very well:<br/> <br/> dd if=<image file> of=<sd card device><br/> <br/> <br/> <br/> except for one thing...   the size of the device is encoded in the partition table (typically the first sector) and if you overwrite that, thin...
by sylvan
Wed Jan 25, 2012 4:14 pm
Forum: Other projects
Topic: PiCard - GUI SD Preparation Tool
Replies: 268
Views: 73456

Re: PiCard - GUI SD Preparation Tool

<r>Montekuri said:<br/> <br/> <br/> And if this is a ISO img we can just use ISO to USB app to write to a SD card:<br/> <br/> <URL url="http://www.isotousb.com/">http://www.isotousb.com/</URL><br/> <br/> We can use a USB Card Reader to write to the SD card:<br/> <br/> <URL url="http://www.amazon.com...
by sylvan
Mon Jan 23, 2012 5:20 pm
Forum: General discussion
Topic: RTC
Replies: 36
Views: 15850

Re: RTC

<r>Crundy said: <br/> <br/> <br/> I bought one of these a while back which I'm going to solder to the GPIO:<br/> <br/> <URL url="http://www.ebay.co.uk/itm/2707.....1439.l2649">http://www.ebay.co.uk/itm/2707.....1439.l2649</URL><br/> <br/> <br/> Looks like a good choice, especially with the 3.3v supp...
by sylvan
Wed Jan 18, 2012 4:59 am
Forum: Other projects
Topic: Automatic power on/off
Replies: 51
Views: 24493

Re: Automatic power on/off

<t>kspn said:<br/> <br/> <br/> Edit: Also if you power the device software down, can you power it back on without switching the power supply on/ff (for example pressing a key on a USB keyboard)<br/> <br/> <br/> Not by pressing  a key on a usb keyboard, or on anything powered by the R-Pi.  The R-Pi h...
by sylvan
Tue Jan 17, 2012 8:50 pm
Forum: Arch
Topic: ArchlinuxARM on Raspberry Pi
Replies: 145
Views: 64098

Re: ArchlinuxARM on Raspberry Pi

<t>pepedog said: <br/> <br/> <br/> device node) (2nd bit of thinking, the 1700 is the size of card, I could have gone higher with the 2Gb used but being safe, an 8Gb card<br/> <br/> <br/> Instead of specifying the size of the card, let parted figure it out.  Just put "100%".  (You could also be expl...
by sylvan
Tue Jan 17, 2012 8:44 pm
Forum: Other projects
Topic: Automatic power on/off
Replies: 51
Views: 24493

Re: Automatic power on/off

<t>error404 said:<br/> <br/> <br/> Also rather than having the Pi itself turn off external power, I'd prefer a failsafe design, using an external timer to shut power off after a minute or something so that a hung shutdown process doesn't leave you with a car that won't start.<br/> <br/> <br/> More c...
by sylvan
Tue Jan 17, 2012 4:23 am
Forum: Other projects
Topic: Tailor-Made Programming Language
Replies: 49
Views: 10825

Re: Tailor-Made Programming Language

<t>Chromatix said: <br/> <br/> <br/> A slight quibble: in assembly, a NOP doesn't do precisely nothing.  It emits an instruction which, when executed by the CPU, does nothing.<br/> <br/> <br/> I can quibble with the best of them.  <br/> <br/> In Python, pass doesn't do precisely nothing.  It is an i...
by sylvan
Tue Jan 17, 2012 12:57 am
Forum: Other projects
Topic: Tailor-Made Programming Language
Replies: 49
Views: 10825

Re: Tailor-Made Programming Language

<t>tritonium said:<br/> <br/> <br/> My first 'hi level' language was a 'tiny basic' on an 8080 homemade computer more than 30 years ago.<br/> ...<br/> <br/> If that first language had been 'C' I think I would have given up.<br/> Even now after all these years I loath and detest 'C'. ...<br/> I'd muc...
by sylvan
Tue Jan 17, 2012 12:31 am
Forum: Other projects
Topic: Tailor-Made Programming Language
Replies: 49
Views: 10825

Re: Tailor-Made Programming Language

<t>Chromatix said: <br/> <br/> After all, what good is syntax that does nothing?<br/> (Hmm, Python has a "pass" statement which does precisely that.)<br/> <br/> <br/> So does C (;).<br/> <br/> So does shell script (:)<br/> <br/> So does almost every processor ever built (the No Operation, NOP, NOOP,...
by sylvan
Tue Jan 17, 2012 12:07 am
Forum: Other projects
Topic: Automatic power on/off
Replies: 51
Views: 24493

Re: Automatic power on/off

<t>Abishur said:<br/> <br/> <br/> From boot to GUI was about a minute thirty.  Not the best for car applications, I know, but not exactly the end of the world either.  I bet you could shave a lot of time off that by stripping away most the system and having it boot straight into your MP3 application...
by sylvan
Mon Jan 16, 2012 11:55 pm
Forum: Other projects
Topic: Automatic power on/off
Replies: 51
Views: 24493

Re: Automatic power on/off

<t>Gert said: <br/> <br/> <br/> <br/> one of the first things it should do is turn on the GPIO pin, thus latching itself on for when the +12v signal disappears.<br/> <br/> <br/> It has GPIO pins with build-in pull-ups. Use one of those to switch the USB battery on. That way you do not have to make a...
by sylvan
Mon Jan 16, 2012 11:53 pm
Forum: Other projects
Topic: Automatic power on/off
Replies: 51
Views: 24493

Re: Automatic power on/off

kspn said:


Item #2/3 look like what I want to do,


You need all 3.

#1 tells the R-Pi your car is off (or on).

#2 allows the R-Pi to turn itself off.

#3 allows the R-Pi to turn on, and is required because of #2.
by sylvan
Mon Jan 16, 2012 10:16 pm
Forum: Other projects
Topic: Automatic power on/off
Replies: 51
Views: 24493

Re: Automatic power on/off

<t>there is no power button.<br/> <br/> There are several steps or phases to solving your scenario, which will require 2 GPIO pins on the R-Pi and some additional components.<br/> <br/> 1) shutdown. With the car switched +12v and a couple of passive components connected to a GPIO configured as a dig...
by sylvan
Sat Jan 14, 2012 5:26 am
Forum: General discussion
Topic: MythTV Front-end
Replies: 34
Views: 19747

Re: MythTV Front-end

It should be easy to attach an IR receiver (ca. $2) to a GPIO.  See how they do it with any microcontroller such as an Arduino.

XBMC might be a better choice for a front-end.
by sylvan
Thu Jan 12, 2012 5:32 pm
Forum: Off topic discussion
Topic: Database error on website
Replies: 23
Views: 3710

Re: Database error on website

Maybe if the forum notified only once per topic (instead of once per post per topic) the database would not be so overloaded...
by sylvan
Thu Jan 12, 2012 5:20 pm
Forum: General discussion
Topic: Monitoring Demand
Replies: 11
Views: 2408

Re: Monitoring Demand

<t>Jaseman said: <br/> <br/> <br/> Until someone gets their Mum to order one on their behalf, and all their friends at work, and their auntie and the bloke next door....<br/> <br/> <br/> <br/> And everyone that has not joined the forum but is waiting to buy (I know several who just watch the website...

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