[dorkbotpdx-blabber] raspberry pi + Qt Creator + vanagon

[Brett]

My wife and I are actively displaying a complete lack of clear judgment
by buying a 1985 Vanagon camper. It's begging to be geeked out. I want
to make a central display screen with data to keep the driver informed
of the status of the various systems on the vehicle. Volkswagen was
never very preoccupied with providing information to the driver--it
wasn't until 1962 that they relented and added a fuel gauge. I think
that this would be a good project for my raspberry pi. Initially, I
want to monitor the operation of the fridge(to make sure the beer is
could when I stop for the night and that the hummus isn't culturing new
life forms) and the charge status of the primary and auxiliary
electrical systems. Then add additional monitoring as time goes on.
Down the road a ways, I want to replace the rather uninspiring
wasserboxer engine with a nice strong modern Subaru OBDII compliant
powerplant. I believe Subaru uses a CAN network for its systems
communications and I want to be able to tie into that and monitor that
data as well.

So I'm looking to build a graphically based monitoring display that can
communicate with at least i2c, a CAN network, and probably some analog
signals as well(which could also be mediated with i2c ADC's or an
arduino), and who knows what else. I'm starting to play around with Qt
Creator since there is a port being developed for the raspberry pi. It
looks like it could handle the graphical display okay, but I'm not sure
about the low level communications with sensors. This level of
programming is well above my skill set, and I don't mind putting in the
time to learn it, but I don't want to find myself 200 hours into the
project completely frustrated because I chose a tool that's
inappropriate for the task. For those in the know, is Qt Creator
appropriate to the task I have in mind(granted, the details given are
sketchy at best)? Is there another programming language/environment
that might be better?

Regarding the raspberry pi: does anyone know of a place in town that has
reasonably priced DVI/HDMI cables? Internetically they're available for
$4-6 each, but locally they're $30 and up, if you can find them at all.
I like to buy locally, and expect to pay more for the convenience, but i
can't stomach a 600% markup. Tried Rat Shack, Best Buy, Fred Meyer,
Goodwill, Target. Fry's has them for $15, which I could do, but would
rather not drive for 1.5 hours + gas money for the round trip. Right
now I have to plug it into my projector for a display, which is not a
pleasant development environment.


Brett


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[Jared Boone]

On Aug 1, 2012, at 12:16 AM, Brett <bre...@teleport.com> wrote:

> does anyone know of a place in town that has reasonably priced DVI/HDMI cables? Internetically they're available for $4-6 each, but locally they're $30 and up, if you can find them at all.

ENU:

http://enuinc.com/

Or the place that was formerly PC Heidens:

http://www.pchcables.com/

Both should be able to "hook you up"...

- Jared

[Monty Goodson]

I was just about to recommend pchcables as well, which, being out by the Hillsboro airport, may not be any closer than Fry's, but it looks like they have a couple hdmi/dvi options for <$5 right now.

Sounds like a cool project!

Monty

[Eric Timberlake]

(subject change - I seem to look more like spam than an honest replay - stupid to depend on yahoo mail, I guess…)

Very cool sounding project..

RE: cheap cables - PCH cables, both online and locally in a concrete tip-up next to the Hillsboro, Airport. Nearly every cable and cable management accessory for very low prices. I just purchased this for my RPi:

http://www.pchcables.com/2mehddvcama.html

$5.25 seemed very reasonable.

I too am flummoxed by outrageous cable prices at "regular" outlets.. ;-)

-ET-

[Brett]

Forgot all about ENU...I'll give them a call tomorrow.

Thanks!

Brett

[Brett]

On 08/01/2012 12:39 AM, Eric Timberlake wrote:
> (

> $5.25 seemed very reasonable.
>
> I too am flummoxed by outrageous cable prices at "regular" outlets.. ;-)
>

Well...for truly hi-def T.V., especially on a BIG screen, you've got to
run in the neighborhood of 5 amps per signal line inside the cable,
otherwise the greens and reds get washed out...


Ummmhhh...but I don't have any monsters...why do i need a Monster cable?

The cable shouldn't cost more than the 800MHz embedded computer board
that you're plugging it into...

[Brandon]

FYI, on the fridge, there is a thermocouple output that gives you a VERY small amount of DC when the flame is going.

The front of the 'control panel' on the Vanagon Westfalias has a LED that indicates if the fridge is lit or not (small green LED). It's simply taking the signal from the thermocouple, running it through an op-amp, and out-puting to the LED. Very simple and should be easy to piggyback onto.

The failing of most watercooled vanagon's is the ability for the driver to pay attention to the engine temperature. Having some fan-dangled alert system (outside of the small flashing Red LED in the dash) would be good if you're not a gauge watcher.

Enjoy your VW!

I recently thought about doing engine monitoring over CANBUS or similar on my 35ft city bus motorhome conversion but decided that I didn't want to start relying on digital circuitry in something that is so old that it is otherwise all hardwired and analog. So I built a new dash with analog gauges (speedometer is digital) and still have switches and relays for controlling things :-) Beauty in simplicity. The vanagon already has an ECU so might as well go for it!

Brandon Mathis
KD7INF
brand...@gmail.com

[Brett]

On 08/01/2012 10:53 AM, Brandon wrote:
> FYI, on the fridge, there is a thermocouple output that gives you a
> VERY small amount of DC when the flame is going.
>
> The front of the 'control panel' on the Vanagon Westfalias has a LED
> that indicates if the fridge is lit or not (small green LED). It's
> simply taking the signal from the thermocouple, running it through an
> op-amp, and out-puting to the LED. Very simple and should be easy to
> piggyback onto.

Good to know. I'd also like to mount a ds1820 right on the cooling
coils and one out in the open area; between the 3 data points, you'd
have a clear picture of exactly what's going on. It sounds like a lot
of people have had problems with the fridges and use them for regular
storage or take them completely out, but I found a nice article on how
to handle them and make them more efficient.

>
> The failing of most watercooled vanagon's is the ability for the
> driver to pay attention to the engine temperature. Having some
> fan-dangled alert system (outside of the small flashing Red LED in the
> dash) would be good if you're not a gauge watcher.

I can do some pretty decent daydreaming while driving and don't always
pay the gauges their due , so having an adjustable alert system to warn
you well before the danger point would be nice. Also, you can monitor
much more than the stock dash provides; oil pressure, charging current,
voltage, etc.

>
> I recently thought about doing engine monitoring over CANBUS or
> similar on my 35ft city bus motorhome conversion but decided that I
> didn't want to start relying on digital circuitry in something that is
> so old that it is otherwise all hardwired and analog. So I built a new
> dash with analog gauges (speedometer is digital) and still have
> switches and relays for controlling things :-) Beauty in simplicity.
> The vanagon already has an ECU so might as well go for it!
>

I haven't looked into what the ECU on the vanagon has to offer, but it's
probably pretty crude. A newer Sooby engine, on the other hand, has a
ton of data generated. It'd be nice to know of developing problems well
before check engine light comes on.


After thinking over things quite a bit, I've decided that an Android
tablet would be a better way to go than the Raspberry Pi. Main
advantages: built in touch screen, wifi, and a ton of available
automotive apps already available to make it a one stop data center for
the van. It doesn't have GIO's, but I could link it with an IOIO or
something similar to gather data input. Now I've got to start looking
at programming platforms for the Android.


Brett

[Brandon]

Not sure why people bash the fridges so badly...probably because people forget they are a combustion chamber as must be cleaned from time to time. My fridge in my '74 (grafted in from a westy like yours) makes ice cubes in the heat of the day (100F+) at Burning Man....they work fine....and a tank of fuel with light to medium cooking use will last you 2-3 weeks. There are some good 'mods' like replacing the thermal grease between the cooling fins and the tube at the back of the fridge (just pull hard on the aluminium bit, it pops off), cleaning the jet in the burn box, and the magic one being adding a very small CPU style pancake fan to the top right corner of the cooling fins inside the compartment to help move air around inside the fridge (causes MUCH more even cooling of food/beverages).

As far as the engine swaps and fuel management goes...have fun! I put purely mechanical fuel injection on my vw to avoid issues :-) It was a total 'hack' in the true sense of the word but it puts most of the 80's electronic fuel injection systems to shame. Not bad for 30 year old parts haha. Not much for write up, but I have some carb to injection photos up here: http://zestybus.com/cis_conversion.php

Having OBDI or OBDII data available to you can definitely help with diagnostics, but I don't think it will help you see problems before they flip the engine light on. The eyeballs scanning over the drive-train before every long trip is best for that :-)

The data is nice...but working properly you should never need to look at or be involved with it. Can definitely detract from the experience of keeping the bread loaf on the road :-)

Cheers,

 

Brandon Mathis
KD7INF
brand...@gmail.com

[Erik Lane]

> Well...for truly hi-def T.V., especially on a BIG screen, you've got to run
> in the neighborhood of 5 amps per signal line inside the cable, otherwise
> the greens and reds get washed out...

Why should it need 5 amps per signal? If it's just a data line why
can't it just be a low level signal and get amplified to whatever
levels are necessary inside the display? Am I missing something basic
here?

[Neal]

On Wed, Aug 1, 2012 at 7:14 PM, Erik Lane <erik...@gmail.com> wrote:
>> Well...for truly hi-def T.V., especially on a BIG screen, you've got to run
>> in the neighborhood of 5 amps per signal line inside the cable, otherwise
>> the greens and reds get washed out...
>
> Why should it need 5 amps per signal? If it's just a data line why
> can't it just be a low level signal and get amplified to whatever
> levels are necessary inside the display? Am I missing something basic
> here?

Brett's sense of humor.

[Scott Dixon]

I got a DVI/HDMI cable that works with my rpi at Surplus Gizmos for around $5 or $6.

On Aug 1, 2012, at 12:24 AM, Jared Boone <jbo...@earfeast.com> wrote:

[Brett]

On 08/01/2012 07:14 PM, Erik Lane wrote:
>> Well...for truly hi-def T.V., especially on a BIG screen, you've got to run
>> in the neighborhood of 5 amps per signal line inside the cable, otherwise
>> the greens and reds get washed out...
> Why should it need 5 amps per signal? If it's just a data line why
> can't it just be a low level signal and get amplified to whatever
> levels are necessary inside the display? Am I missing something basic
> here?
>

;-) No, you ain't missing a thing...I was just spoofing the trend best
exemplified by the Monster Cable brand where they try to convince you
that you need massive high performance cables(at equally outrageous
prices) in order to get good performance out of your A/V system. I
don't mind the fleecing of the ignorant too much as long as they also
offer the "cheapy" cables that provide 99.44% of the performance of the
premium cable for 1/5 of the cost.

Sorry, I shoulda put a grinning icon with the original post.



Brett

[Brett]

On 08/01/2012 08:55 PM, Scott Dixon wrote:
> I got a DVI/HDMI cable that works with my rpi at Surplus Gizmos for around $5 or $6.
>
>
>

I wish Surplus Gizmos was closer to my home; they have some fun stuff.
I went to ENU & picked up a cable for $8 & was quite pleased. Best Buy
will sell you one online for $5, but the best I could do at their store
was well over $30 and required combining a DVI/HDMI adapter and a
separate HDMI cable.

I did overpay quite a bit for the micro-usb power supply. The micro-usb
phone chargers haven't really trickled down to the Goodwill stores much
and I got tired of searching. That'll teach me not to hang onto my cell
phone for 4 years...


Brett

[Brian Collins]

Speaking of power, I just got my pi yesterday, and was about to head
to PCH Cable when I realized my kindle came with a micro usb cable,
and my apple switching power supply (the little white usb plug bricks)
can supply in excess of what the pi needs. dunno why i didn't think of
that earlier, but anyway so far it's been working great. maybe the
kindle usb plug could handle the pi's needs, but i had more confidence
in the apple one after reading about a teardown of it recently:

http://www.arcfn.com/2012/05/apple-iphone-charger-teardown-quality.html

[Scott Dixon]

The Kindle charger seems to work fine. In fact, the chargers for many of the tablets are likely to be good choices. Generally, they are set up to supply more current than the run of the mill USB power supply so they are ideal for the RPi. Many of the phone chargers are a bit marginal in terms of current for the RPi. You need to check the output specs. I scrounged through the Surplus Gizmos wall wart box and found an adapter for the Nook Color which puts out plenty of power. One caution on that one is that the Nook Color uses an odd plug which looks like a micro USB but isn't (it is longer and has some extra pins). But the wall wart itself works fine with a normal micro USB cable.

[Neal]

On Wed, Aug 1, 2012 at 9:49 PM, Brett <bre...@teleport.com> wrote:

> On 08/01/2012 08:55 PM, Scott Dixon wrote:
>>
>> I got a DVI/HDMI cable that works with my rpi at Surplus Gizmos for around
>> $5 or $6.
>>
>>
>>
> I wish Surplus Gizmos was closer to my home; they have some fun stuff. I
> went to ENU & picked up a cable for $8 & was quite pleased. Best Buy will
> sell you one online for $5, but the best I could do at their store was well
> over $30 and required combining a DVI/HDMI adapter and a separate HDMI
> cable.

Two words: Store Pickup. Order online, pickup locally after a short
processing interval (seems like it was < an hour, maybe two) at the
online price, assuming it's in stock at that store.

NealS

[Erik Lane]

On Wed, Aug 1, 2012 at 9:37 PM, Brett <bre...@teleport.com> wrote:
> On 08/01/2012 07:14 PM, Erik Lane wrote:
>>>
>>> Well...for truly hi-def T.V., especially on a BIG screen, you've got to
>>> run
>>> in the neighborhood of 5 amps per signal line inside the cable, otherwise
>>> the greens and reds get washed out...
>>
>> Why should it need 5 amps per signal? If it's just a data line why
>> can't it just be a low level signal and get amplified to whatever
>> levels are necessary inside the display? Am I missing something basic
>> here?
>>
> ;-) No, you ain't missing a thing...I was just spoofing the trend best
> exemplified by the Monster Cable brand where they try to convince you that
> you need massive high performance cables(at equally outrageous prices) in
> order to get good performance out of your A/V system. I don't mind the
> fleecing of the ignorant too much as long as they also offer the "cheapy"
> cables that provide 99.44% of the performance of the premium cable for 1/5
> of the cost.
>
> Sorry, I shoulda put a grinning icon with the original post.
>
>

Okay, thanks for the clue stick!! :)