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Re: 4.41 inch ePaper Display for the rPi

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On Fri, 19 Jun 2015 17:35:10 -0400, rickman wrote:

> I'm not really following you here.  Color is better than BW so the Kobo
> must be ePaper?
>
No, colour is generally better than monochrome, all other things being 
equal. But for outdoor use under an open sky a high contrast monochrome 
display is preferable given that any colour display apart from coloured 
ePaper is going to be washed out and hard to read, especially with direct 
sunlight on the display.

Thats no different from trying to use a viewfinderless camera outdoors on 
a sunny day, but you'll know that.

 
> Why don't you ask the people who have the Kobo how fast it updates?
>
Because there is nobody at my club who is using a Kobo. Question posted 
on rec.aviation.soaring
  
> Again, I'm not following.  If you have an Andriod app, how does that get
> an ePaper display?
>
It doesn't, but it does tend to get you a commercial device with standard 
standard APIs for accessing its colour display and touch screen, enough 
flash memory to install the app on and facilities for uploading maps etc 
and for downloading flight logs.
  
> When you say rPi, you mean Linux.  There is not really anything special
> about the rPi that I have been able to see.  I'm a rank novice with
> Linux but nearly everything I've learned about it applies equally to any
> Debian system.
> 
Indeed, and it gets you a device that is small, light, not particularly 
hungry and cheap. As I said, I have a feeling that LK8000 has been ported 
to it, which would mean that somebody has added code to use SPI or I2C to 
handle small displays. It has to be them since we know there are no 
suitable HDMI displays and, although the el-cheapo Chinese back-up video 
displays accept a composite signal, the resolution looks to be 
unacceptably low.

The Beagle Board might also do the trick, but (so far) its not been 
mentioned as possible hw for LK8000.
 
> You are talking about the lag in your GPS?  Yes, I've seen that with
> hand held units even while walking, lol.  To get real time updates... I
> mean truly real time, you need an inertial nav system.  Entirely
> possible with a simple G force sensor like they use in phones these
> days.  It requires some data fusion as the sensor won't be as accurate
> long term as the GPS, but over the short interval the sensor is faster
> to respond.
>
Some of the better varios are using 3D accelerometer arrays, but that's 
for gust sensing. Similarly, solid state blind flying panels are now 
common, good and quite cheap but lets not go there: they are for a rather 
different purpose.
  
> Ok, so for your app power is not really an issue.  Do you run from
> batteries or use a prop powered generator?
>
Batteries. Wind driven generators cause drag which stuffs glide 
performance. 12v systems are almost universal (Light aircraft use higher 
voltages). I carry a pair of 12v 7AH lead-acid batteries which can easily 
run my electronics for more than the longest day.

> I've never seen any sort of
> prop on a glider (I live very near an airport so I do get to see a lot
> of them).
>
Wander over one day, take a look and ask questions. Pilots are friendly 
and generally happy[*] to talk, answer questions and show you stuff

* just don't talk to a man who is in the middle of assembling and pre-
flighting a glider: he needs to concentrate on what he's doing.
 
Propellers: some gliders do have them because they carry auxiliary 
engines: if conditions deteriorate they can fire up and fly home rather 
than ending up in some farmer's field. Usually the engines and props are 
retracted behind the cockpit so you can't see them and come out on a 
pylon when needed, but nose-mounted, electrically driven folding props 
and small gas turbines are becoming popular. However, piston engines are 
still the most common, if the most problematic - because they add a huge 
amount of drag when extended, which is a big problem when it doesn't 
start. Thats why electric and jets are coming in: electric always starts 
and an extended jet adds very little drag even when not running. 

I fly a pure glider and usually winch launch rather than aero tow.
 
> I just wondered if the weight of a generator would be less
> than the battery, but maybe you don't need a large battery so the weight
> just isn't an issue.
>
Depends: at one extreme the Antares 20E is a 20m span electric self-
launcher with a pop-up 47 kW brushless motor and wings full of batteries. 
It has the power to take off and climb 10,000 ft. I have no idea what its 
batteries weigh. At the other end of the battery scale my pair of 7AH 
motorcycle batteries only add about 5 Kg to a glider with a normal flying 
weight of 280 Kg. 


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |

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Re: 4.41 inch ePaper Display for the rPi Martin Gregorie <martin@address-in-sig.invalid> - 2015-06-18 22:39 +0000
  Re: 4.41 inch ePaper Display for the rPi Martin Gregorie <martin@address-in-sig.invalid> - 2015-06-19 19:10 +0000
    Re: 4.41 inch ePaper Display for the rPi rickman <gnuarm@gmail.com> - 2015-06-19 15:34 -0400
      Re: 4.41 inch ePaper Display for the rPi Martin Gregorie <martin@address-in-sig.invalid> - 2015-06-19 20:36 +0000
        Re: 4.41 inch ePaper Display for the rPi Martin Gregorie <martin@address-in-sig.invalid> - 2015-06-19 23:22 +0000
        Re: 4.41 inch ePaper Display for the rPi Martin Gregorie <martin@address-in-sig.invalid> - 2015-06-19 23:58 +0000
          Re: 4.41 inch ePaper Display for the rPi hamilton <hamilton@nothere.com> - 2015-06-19 18:25 -0600
          Re: 4.41 inch ePaper Display for the rPi rickman <gnuarm@gmail.com> - 2015-06-19 22:44 -0400
            Re: 4.41 inch ePaper Display for the rPi rickman <gnuarm@gmail.com> - 2015-06-20 13:29 -0400
        Re: 4.41 inch ePaper Display for the rPi cl@isbd.net - 2015-07-29 10:26 +0100
          Re: 4.41 inch ePaper Display for the rPi cl@isbd.net - 2015-07-29 21:21 +0100
            Re: 4.41 inch ePaper Display for the rPi rickman <gnuarm@gmail.com> - 2015-07-29 17:18 -0400
              Re: 4.41 inch ePaper Display for the rPi cl@isbd.net - 2015-07-30 10:23 +0100
                Re: 4.41 inch ePaper Display for the rPi Rob <nomail@example.com> - 2015-07-30 11:14 +0000
                Re: 4.41 inch ePaper Display for the rPi Dom <domafp@blueyonder.co.uk> - 2015-07-30 12:55 +0100
                Re: 4.41 inch ePaper Display for the rPi cl@isbd.net - 2015-07-30 13:15 +0100
  Re: 4.41 inch ePaper Display for the rPi Theo Markettos <theom+news@chiark.greenend.org.uk> - 2015-06-19 20:27 +0100
    Re: 4.41 inch ePaper Display for the rPi rickman <gnuarm@gmail.com> - 2015-06-19 15:57 -0400
  Re: 4.41 inch ePaper Display for the rPi Martin Gregorie <martin@address-in-sig.invalid> - 2015-06-19 19:31 +0000

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