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Hi Lee, all,<br>
<br>
Yes, sorry. Typo... The Pi has a built-in baseband 640x480 video
(aka RCA) output, so I won't need the adapter box.<br>
<br>
I'm expecting to run the video through a simple SPDT switch to
select either the Pi or backup camera. If I get fancy, maybe tie
that to the car's backup signal and use a relay to switch
automatically. No need or intention to sacrifice one for the other.<br>
<br>
My expectation is that the system will be on RF primarily, though I
haven't located a good place for the antenna. I was initially
thinking to use a small bi-directional tracker-like module (Rx and
TX required), but will probably start with my Kenwood D7. If I can
do tethering with my cell phone, I might be on IS too.<br>
<br>
The Accessory outlet does remain on for several minutes after
parking, but I really need to have something that's automatic
because I'd likely forget. So, either I make the Pi's file system
read-only (so it doesn't care about abrubt loss of power), or
trigger the shutdown automatically. My thought is to put a small 5v
NiCd battery on the 5v input rail, to hold the Pi running for a bit,
and trigger a shutdown when the +12 input goes away. I'm not very
familiar with the Pi yet, so perhaps it has a low power suspend
mode, where a small battery could hold it for a couple of weeks.
That would probably be ideal, though I'd still need to trigger the
state changes. Haven't had a chance to investigate this, beyond
recognizing that the issue exists, at least in theory. Am I
over-designing this?<br>
<br>
On the topic of the operator control, perhaps instead of switches
and GPIO pins, I recalled after my posting that some cars have
essentially a joystick mouse-like control mounted between the
seats. I'm not sure how well this would work on the small screen,
but that might solve the problem. Anybody have one of these cars,
and could relate how it works?<br>
<br>
Greg KO6TH<br>
<br>
<br>
<div class="moz-cite-prefix">Lee Bengston via aprssig wrote:<br>
</div>
<blockquote
cite="mid:CAPF_JSLkrdbaFW5yH4iRw7NmKMX19RDA6HiKzhCKCdnLSp9stA@mail.gmail.com"
type="cite">
<p dir="ltr"><br>
On Jan 17, 2016 12:24 AM, "Greg D via aprssig" <<a
moz-do-not-send="true" href="mailto:aprssig@tapr.org">aprssig@tapr.org</a>>
wrote:<br>
><br>
> Hi folks,<br>
><br>
> Picking up on a thread I started a while back... Not sure
if this will lead to something permanent or not, but I tought
I'd give it a try.<br>
><br>
> I got access to the back of my car's in-dash unit, and the
video input connector. It's meant for use with a back camera,
which I currently don't have (though it's on the wish list...).
Found a VGA to RCA adapter box, and fired up APRSIS32 which was
loaded on a small laptop. Here's the result:<br>
><br>
> <a moz-do-not-send="true"
href="http://home.wavecable.com/%7Eko6th/aprs_dash_display.jpg">http://home.wavecable.com/~ko6th/aprs_dash_display.jpg</a><br>
> <a moz-do-not-send="true"
href="http://home.wavecable.com/%7Eko6th/aprs_laptop.jpg">http://home.wavecable.com/~ko6th/aprs_laptop.jpg</a><br>
><br>
> Given the difficulty, if not questionable legality, of
controlling a GUI-based laptop while driving, I think the next
steps need to include:<br>
><br>
> 1. Replace the laptop and VGA adapter with a Raspberry
Pi. VGA output is built-in, also much better power draw and
small size. (The car is a sports car, so no room for anything
bigger.)</p>
<p dir="ltr">I think you meant RCA is built in, right?</p>
<p dir="ltr">> 2. Replace APRSIS32 with YAAC (for Raspberry Pi
compatiblity).<br>
><br>
> 3. Probably still need a keyboard for full control while
parked, but add some fixed key switches tied to keyboard
shortcuts for the common stuff while driving. During the
earlier exchange, Andrew figured it was a "simple" matter of a
Java library to bridge the swtiches to keyboard shortcuts...
Hope he's right.<br>
><br>
> 4. The Pi will boot itself when the car turns on, but I
need a way to automatically safely power down the Pi when I turn
the car off. Any ideas on this?<br>
><br>
A lot of vehicles don't shut the radio off immediately - will
eventually time out - and many will shut off once you open the
door. You could source the power from a source that doesn't
shut off right away and buy yourself time to shut down
gracefully.</p>
<p dir="ltr">Sounds like fun - my truck has a backup camera that I
would not want to be without. :-)</p>
<p dir="ltr">Lee - K5DAT</p>
<br>
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