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  Reply # 1246607 25-Feb-2015 18:22
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fizzychicken:

 

  • run openelec off a good usb key not the SD card.
The operative word is "good".  We thought Imation should be good to ship with our products(http://usb-flash-drive.blogspot.co.nz/2007/07/imation-4gb-nano-flash-drives.html), did not take long until we dumped the stock and got a good quality (and expensive) memory stick.  It would be dead out of the box, or die with a short service life (weeks to months).

I don't know what the new one is, but was told we pay around $60 each (bought by the box, not on-off) for a relatively small size, maybe 8GB, but it is industrial spec.  Will find out what it is if I remember.




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  Reply # 1246617 25-Feb-2015 18:24
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fizzychicken: the benefit is in part to reduce the risk of corruption


IMO a USB socket is more reliable than an SD card socket.  USB has to handle a much higher bandwidth than SD cards.




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  Reply # 1246654 25-Feb-2015 19:46
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Its only USB2 on the pi, so thruput is much much lower than a basic UHS1 interface SD card can achieve.




Richard rich.ms

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  Reply # 1246712 25-Feb-2015 21:57
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richms: Its only USB2 on the pi, so thruput is much much lower than a basic UHS1 interface SD card can achieve.

It does not matter what is on the Pi, it is still a USB socket and meets the USB spec.  The SD card on the other hand gets its speed from a 4-bit parallel bus running at 100MHz, not a single bit running at 240MHz.  The USB signalling is also spec'ed to run over a long cable, where as SD is spec'ed for a short circuit trace.  Then there is differential pair with impedance matching between pairs as well as to ground vs. single ended which has impedance matching only to ground.  USB as a connector standard is much more reliable than SD, and significantly less susceptible to interference.




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  Reply # 1246749 25-Feb-2015 22:53
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well I just wired up a this relay module to open my garage door via the pi.  that was fun, now can open it via phone/openhab.  I'll tidy everything up in the weekend and install these contact switches to tell when the door is closed or open (currently wires are just hanging out the garage door opener to a table with the pi).

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  Reply # 1246832 26-Feb-2015 09:29
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Thanks for pointing out about the relay module. I was  also looking for one.
I'm looking at the relay datasheet from here:
http://www.farnell.com/datasheets/1514128.pdf

and found this:

Max switching capacity of 1200VA, 240W. Is that right?




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  Reply # 1246943 26-Feb-2015 11:12
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reven: well I just wired up a this relay module to open my garage door via the pi.  that was fun, now can open it via phone/openhab.  I'll tidy everything up in the weekend and install these contact switches to tell when the door is closed or open (currently wires are just hanging out the garage door opener to a table with the pi).


Nice - Any chance you can blog your solution with some notes and pictures.




Generally known online as OpenMedia, now working for Red Hat New Zealand as a Solution Architect for all things Linux, Virtual and of course Cloud. Still playing with MythTV and digital media on the side.

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  Reply # 1246962 26-Feb-2015 11:14
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just basically followed these directions :)



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  Reply # 1246964 26-Feb-2015 11:19
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reven: just basically followed these directions :)




Got most of the bits, now just need to find some time!

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  Reply # 1247277 26-Feb-2015 19:39
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russelo: Thanks for pointing out about the relay module. I was  also looking for one.
I'm looking at the relay datasheet from here:
http://www.farnell.com/datasheets/1514128.pdf

and found this:

Max switching capacity of 1200VA, 240W. Is that right?




Old datasheet with errors.  Get the current datasheet off the Omron web site.

Note minimum contact current, but I can't find that spec in the new datasheet (which does not cover obsolete cadmium-containing contacts, so the plating might have changed and maybe is no longer an issue).  There are contact platings used in many high power relays that will not work reliably for low current signals.




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  Reply # 1247306 26-Feb-2015 20:12
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Slightly OT but here goes, it relates to the Pi 2 B.  My wife and I are both engineers and work at the same company (actually she is my project manager, but I'm used to it...).  She is unofficial morale officer, and arranging something for Pi Day (date written in American format, 3.1415 as in March 14 2015).  There is a pie baking competition and the prize is a Raspberry Pi 2 B which must be the most geeky use for the latest Pi.  Add to that a geeky pub quiz and as prizes a number of 3D printed pencil holders like this http://pbs.twimg.com/media/BroQ48SCUAA4s5U.jpg




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  Reply # 1249121 2-Mar-2015 07:35
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Well this weekend I managed to do the following with my pi.

 

  • reed switches to record state off a internal garage door closed
  • reed switch to tell when the garage door is closed
  • reed switch to tell when the garage door is fully open
  • relay module fully working now to open garage door

     

    • On = open, off = closed, so its a virtual switch in openHAB.
    • wont trigger, if you send an on command if door is already open or is in transition (hence the open reed switch)
    • wont trigger, if you send an off command if door is already closed or is in transition (hence the close reed switch)
    • reed switches will update openHAB, so if someone opens the door manually or via the physical push button, openHAB is updated
    • I had to wire up the physical button to the pi, the button wouldnt work with that + the relay module going into the garage door opener. so physical -> pi -> pi triggers relay 
    • The wireless remotes for the garage door no longer work, but can open via phone
    • Thanks to SumnerBoy I now am able to shake my LG G Watch R the say "Open|Close garage door" to open|close.  This works very well.  If already open, saying "Open garage door", wont open the door.  I can say "Toggle garage door" to simulate the button push if for some reason the state is wrong or if I want to stop the door from opening/closing.
  • Added a motion sensor but this one is far to weak and has a very small range (about 2 metres) so need to find a better one to hook up to a pi.  Normal PIRs use 12v, so the pi won't power that.  I could power them from a computer power supply I guess and just add the contact wires to the pi....  But rather keep everything on the pi.

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  Reply # 1249169 2-Mar-2015 09:40
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reven: Well this weekend I managed to do the following with my pi.

 

  • reed switches to record state off a internal garage door closed
  • reed switch to tell when the garage door is closed
  • reed switch to tell when the garage door is fully open
  • relay module fully working now to open garage door

     

    • On = open, off = closed, so its a virtual switch in openHAB.
    • wont trigger, if you send an on command if door is already open or is in transition (hence the open reed switch)
    • wont trigger, if you send an off command if door is already closed or is in transition (hence the close reed switch)
    • reed switches will update openHAB, so if someone opens the door manually or via the physical push button, openHAB is updated
    • I had to wire up the physical button to the pi, the button wouldnt work with that + the relay module going into the garage door opener. so physical -> pi -> pi triggers relay 
    • The wireless remotes for the garage door no longer work, but can open via phone
    • Thanks to SumnerBoy I now am able to shake my LG G Watch R the say "Open|Close garage door" to open|close.  This works very well.  If already open, saying "Open garage door", wont open the door.  I can say "Toggle garage door" to simulate the button push if for some reason the state is wrong or if I want to stop the door from opening/closing.
  • Added a motion sensor but this one is far to weak and has a very small range (about 2 metres) so need to find a better one to hook up to a pi.  Normal PIRs use 12v, so the pi won't power that.  I could power them from a computer power supply I guess and just add the contact wires to the pi....  But rather keep everything on the pi.

This was good timing, I was going to order the bits from your last post, so I need to order 2x reed switches for both open and closed?

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  Reply # 1249170 2-Mar-2015 09:42
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you don't need 2 reed switches, it will work with one, but you wont know if the door is fully open or not.  at like $8? each, I'd grab two.

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  Reply # 1249653 2-Mar-2015 16:49
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The motion sensor should have a much better range when you mount it in a box so that ambient light does not flood the sensor.  Typically there would be a 5V regulator on the sensors, but some might still be 12V.  The alarm output signal might be 12V level, but typically there will be a 5V signal driving a transistor to get a 12V output.  A bit of reverse engineering would quickly show you if you need 12V or not.




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