[aprssig] APRS in-dash display

Stan Leeds srkleeds at sbcglobal.net
Sun Jan 17 13:45:16 CST 2016


There are a number examples of configuring a switch to the GPIOs that 
will properly and safely shut down the Pi and then after that you can 
have a delayed timer to properly shut down the power source.

Good Luck and we anticipate info & pics as you go along.


Stan, KC7EHJ


On 1/17/2016 2:25 PM, Andrew P. via aprssig wrote:
>
> >Subject : [aprssig] APRS in-dash display
> >From: Lee Bengston
> >Date: Sun Jan 17 11:25:02 CST 2016
>
> >
>
> >On Jan 17, 2016 12:24 AM, "Greg D via aprssig" <aprssig at tapr.org 
> <http://www.tapr.org/mailman/listinfo/aprssig>> wrote:
>
> >>/Hi folks,/
>
> >>/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.
>
> >>
>
> >>/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:
>
> >>/http://home.wavecable.com/~ko6th/aprs_dash_display.jpg 
> <http://home.wavecable.com/%7Eko6th/aprs_dash_display.jpg>/
>
> >>/http://home.wavecable.com/~ko6th/aprs_laptop.jpg 
> <http://home.wavecable.com/%7Eko6th/aprs_laptop.jpg>/
>
> />>/
>
> >>/Given the difficulty, if not questionable legality, of controlling 
> a /GUI-based
>
> >> laptop while driving, I think the next steps need to include:
>
> >>
>
> >>/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.)
>
> > I think you meant RCA is built in, right?
>
> >
>
> >>/2. Replace APRSIS32 with YAAC (for Raspberry Pi compatiblity)./
>
> />>/
>
> >>/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.
>
> >>
>
> >>/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?
>
> >//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.
>
>
> >Sounds like fun - my truck has a backup camera that I would not want 
> to be without. :-)
>
> >Lee - K5DAT
>
>
> This is a project I've been fiddling with for a couple years, since I 
> acquired a motor home. However, after a couple years of driving "the 
> moose", I don't think I want to give up the backup camera video 
> monitor, because:
>
>
> 1. The monitor is tiny and black and white (the motor home is an old 
> 2005 model and actually has a 6" CRT monitor, not a LCD/LED one).
>
>
> 2. Driving a vehicle that large and awkward with all the lunatics on 
> the highway, I want all the views I can get of overtaking maniacs so I 
> can be ready for them.
>
>
> However, I could defeat the ignition power interlock for the main TV 
> set (above the windshield) and hook a Pi onto that larger monitor (and 
> I've been looking at replacing that old CRT TV with a flat-screen 12v 
> set anyway), so I could have the Pi view up there.
>
>
> The Pi4j library (http://pi4j.com/) provides Java-language access to 
> the GPIO pins on the Pi, including supporting I2C; as an exercise for 
> the student, I wrote a non-published plugin for YAAC (based on the 
> provided sample plugin) that would copy the text of incoming messages 
> to one of those 16x2 LCD displays that connect to the GPIO pins. Using 
> the same library, you could have YAAC listen to button pushes on one 
> of the Pi daughterboards that provides user input (the LCD module I 
> had also had a few buttons on it, but in places mechanically awkward 
> to put in a project box), and convert a button push into the 
> equivalent of clicking on a menu entry (by calling the 
> actionPerformed() function on the desired menu entry or GUI widget, 
> such as the zoom in or zoom out buttons).
>
>
> Regarding power, I have already had to replace the CD-eating 
> broadcast-band radio in the motor home's dashboard anyway, so I know I 
> have multiple power source wires in the dashboard, some direct from 
> the engine starting battery, some ignition-switched, and some from the 
> coach (RV appliance) battery bank. Not sure what kind of "safe" you 
> need for powering down the Pi; I usually just pull its power cord, 
> although I suppose it should have a proper power cycle and "poweroff" 
> command for flushing disk caches from writing the YAAC log files; you 
> could figure that out with a GPIO pin connected to switched power 
> (through an appropriate voltage divider so you don't fry the Pi), and 
> using one of those timed poweroff devices that are sold to protect 
> your battery from being overdrained by your ham radio rig when the 
> ignition is off (just make sure the time is longer than the interval 
> needed for the Pi to shut down) to feed the power to a 12v-to-5v 
> converter for the Pi.
>
>
> I have found a few tiny (approx. 6" long) Bluetooth keyboard/mouse 
> gadgets that work well with the Pi over the WiPi USB plugin, so you 
> could shove said keyboard in the door pouch and pull it out when 
> needed (i.e., when parked).
>
>
> I've mostly been delayed on this project by trying to figure out how 
> to wire an anemometer on the roof of the RV without putting more leaks 
> in the roof, having the anemometer destroyed by the first low-hanging 
> tree branch I pass, or wrecking the interior trim trying to get the 
> anemometer wiring back to the Pi at the dashboard.
>
>
> I strongly recommend using the Pi 2 for this project, as YAAC is not a 
> very fast renderer of streets on a Pi (despite all the effort I've put 
> into making the street renderer faster); you'll need all the CPU power 
> you can get.
>
>
> Just my $.02.
>
>
> Andrew, KA2DDO
>
> author of YAAC
>
>
>
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