Today's Message Index:
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1. 11:07 AM - Re: Constructing an automatic RCA video camera feed splitter (Eric Page)
2. 12:00 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Robert L. Nuckolls, III)
3. 12:09 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Robert L. Nuckolls, III)
4. 01:20 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Charles Davis)
5. 03:13 PM - Re: B&C Alternator and Voltage Regulator (Robert L. Nuckolls, III)
6. 04:15 PM - Re: Constructing an automatic RCA video camera feed splitter (Eric Page)
7. 05:10 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Alec Myers)
8. 07:01 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Robert L. Nuckolls, III)
9. 07:44 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Alec Myers)
10. 11:05 PM - Re: Constructing an automatic RCA video camera feed splitte (Eric Page)
Message 1
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| Subject: | Re: Constructing an automatic RCA video camera feed |
splitter
alec(at)alecmyers.com wrote:
> How about have the rate program mode entered by powering up with the right button
held down, and the camera quantity select mode entered by powering up with
the left button held down. That saves two pins and a dip switch.
>
> That also means that you can still reprogram the unit without physical access,
and theres still little to no chance of accidentally or ham-fistedly entering
a programming mode. Just dont lean on the panel when you power up the avionics.
Sounds good to me.
> If were really really really paranoid, have a single dip switch - in fact might
as well make it a track that can be cut or a solder pad that can be bridged
- to prevent any programming.
It's probably excessive to do that. Nothing infuriates me more than a manufacturer
who goes to absurd lengths to lock me out of a device I paid good money for!
> Im still conscious of and sensitive to the charge of excessive and unwarranted
buttonology. Why dont we set the un-initialized defaults at 4 cams, and your
choice of 5 second period. Then if you dont care do any programming at all, it
does something useful, and you get 4 cameras off the bat (or even two, or three,
with appropriate solder blob shorts between Cams 1 and 3, and 2 and 4) And
if you have only the right button you can still adjust the scan speed.
I'm not sure I understand what you mean about solder bridges, but I'd prefer not
to create a situation where a builder has to modify the PCB in some way to gain
additional functionality if he adds cameras. Let's just make the default
setting be four cameras (for no other reason than that's what Wade is installing)
and leave it to the programming mode to change it.
I'll just put a single tactile switch on the PCB, in parallel with Panel Switch
(Left), that can be used in the event the user doesn't install the left switch
on the panel. It's a 10-cent part, so no big deal.
> Other than that:
>
> Short press: freeze
> Second and subsequent short press: advance to next or retard to previous camera
> Long press: resume scan in selected direction.
Agree.
> Re pinout:
> RA0, RA1, RA2, RA4 and RA5 are the only pins with weak pull-ups available so
those should be the ones used for button, pad or dip inputs. That is, pins 11,
12, 13, 2 and 3.
>
> So we should move the left panel switch from pin 4. (RA3). During serial programming
Vpp (RA3) is raised to 12v, so whatever is connected to that pin must
be capable of sustaining this high voltage without pulling it down or being damaged.
It may be better to leave RA3 open circuit other than a pad for programming.
OK, I looked at my test layout again, and with the separate programming DIP switches
removed, this is no problem. The pinout looks like this:
01: Vdd
02: Camera 3 Select
03: Panel Switch (Left) / Tactile Switch
04: Vpp
05: -----
06: Camera 8 Select
07: Camera 5 Select
08: Camera 6 Select
09: Camera 7 Select
10: Camera 2 Select
11: Panel Switch (Right)
12: Camera 1 Select / ICSP Clock
13: Camera 4 Select / ICSP Data
14: Vss
The Camera Select lines don't need pull-down resistors, right -- the PIC can actively
pull them low when each channel is off?
I suppose we could use RC5/Pin5 to drive an LED to indicate when the board is in
programming mode. How much current can this pin safely handle, and would you
rather source or sink?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473663#473663
Message 2
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| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
At 08:49 PM 10/17/2017, you wrote:
>In the fantasy world I enjoy inhabiting, where
>I=99ll happily spend four days of engineering
>resource researching a different chip to save
>$0.50 in parts costs (which really only makes
>sense when you anticipate a production run of
>thousands, and let=99s be honest how many people
>are going to build a video switcher?) it=99s
>nice to know that you, Bob, don=99t need to
>commit to programming 10,000 PICs - there exists
>another option, even if it won=99t ever be needed.
exactly . . . one often needs to seek pleasure in
the journey toward the elegant solution. When you're
designing for a potential product flow of thousands,
then pennies/labor matter.
This began as a solution search for a one-off project.
This prompted a search for a short-path to functional
success . . .
Digging around in the junk box, I found some artifacts
from other programs which, after some HOURS of fabrication
effort . . . had a high probability of success.
To be sure, a focused activity to reduce parts/labor
while maximizing functionality can be a lot of fun
and if our customer wants to build lots of them,
equally productive.
But let us suppose our deliberations distill down to
some reasonably elegant design . . . now what? The
original goals are met . . . how's the best way
to spread the value around? Making the data package
public knowledge is easy . . . we'll just post it.
Maybe a youtube video that speaks to procurement,
assembly and installation? Postings on users groups
that point to the video?
The old saw about "building a better mousetrap" is
horse hocky. The ultimate success of useful ideas
is all about promotion . . . disseminating knowledge
to the widest possible audience.
Bob . . .
Message 3
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| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
At 09:28 PM 10/17/2017, you wrote:
>
>
>nuckolls.bob(at)aeroelect wrote:
> > If one wishes to program SOIC chips before installation, adapters
> are avaiable to facilitate this task . . .
> >
> > http://tinyurl.com/yazkcare
>
>
>Yikes! They're available a LOT cheaper than that:
>
>8-Pin: http://preview.tinyurl.com/yasq5txd
>
>14-Pin: http://preview.tinyurl.com/y8ngbp3p
>
>16-Pin: http://preview.tinyurl.com/y7ebhgb3
>
>28-Pin: http://preview.tinyurl.com/y7wmacyr
>
>Eric
To be sure . . . I just clicked on some of the
most accessible options. The point of the posting
was to suggest that acquiring a programmed
chip need not be the longest pole in the
tent.
I have observed that DIY projects are seldom
justified in terms of the economics. I've
sold bare boards for years . . . they've
never been more than a tiny percentage of
product flow off my shelves.
I KNOW that any builder's $time$ expended
in completion of the project will probably
exceed the cost of a factory fabricated
equivalent. I think the prevailing reasons
for DIY projects are (1) no practical
off the shelf alternative has been identified
or perhaps non-existent. (2) the builder
enjoys the journey from bag-o-parts to
functional system.
I got three for four PIC programming tools
laying around. I deduce that it would be no
big deal to offer programming services because
I think the size of that task is going to be
small -and- offering that service cuts a
significant chunk of $time$ from an individual
construction task.
Bob . . .
Message 4
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| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
Hi Guys
For the question of the number of cameras to cater for ... if you didn't
include the option to change the number of inputs, and had for example 8
available, then someone who only wants 2 cameras - they could connect each
camera to 4 inputs, or 4 cameras could be connected to 2 inputs each. A
splitter of some sort should be able to match the impedances fairly well. or
not ?
maybe not practical, just a thought that doesn't seem to have been discussed
... and I'd hate for you-all to run out of input
Charles
Message 5
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| Subject: | Re: B&C Alternator and Voltage Regulator |
At 11:49 PM 10/17/2017, you wrote:
Good evening Bob,
I finished building the Glastar in 1999 and yes,
the system was stable. I wired the ship. The
airplane has an O-320-D2J Lycoming engine with a fixed pitch prop.
I=99d have to look at my records, but 4-years is
about right when the gremlin started showing up.
<snip>
After more trouble shooting, different bus switch
settings, I managed to smoke the EXP bus
alternator polyfuse. Smoking the polyfuse I knew
was a symptom not the problem. I sent the
regulator back to B&C to see if there was
damage. To my understanding, there was none.
. . . and I wouldn't expect any damage.
I sent the EXP bus for repair and thought I might
have a chattering master solenoid, so the
solenoid was also replaced. I also thought the
EXP bus was the problem, so I isolated the EXP
bus from the bus for troubleshooting. The EXP bus was not the problem.
how did 'chattering' manifest? Something
you could hear? Panel equipment misbehaving?
I also tried using the Ford mechanical regulator,
using your wiring diagram. The first time I
thought I may have wired it wrong because I
smoked the regulator. I wired a second one and smoked that too.
"Mechanical"? Dit it look like this . . .
http://tinyurl.com/y842w3o6
or was it a taller one like this?
http://tinyurl.com/y9mjzy28
When you say, "smoked" . . . did it ever
work and quit or never worked. Was there
evidence of 'smoking' like real smoke or
bad smells?
I'm now at the state I previously described to you in the last email.
I kind of jumped the gun and sent the alternator
and regulator back to B&C to run as a system,
although I=99m not convinced those parts are the
problem. When I get the parts back, I=99ll follow
your continued experiment and report back.
I'm 99.9% sure that there's nothing
wrong with the hardware. At the same time,
I'm mystified by the nuisance trips on your
EXP-Bus.
Those alternators run so fast on a Lycoming
that field current in flight is generally
VERY low . . . typically less than 1/2 amp.
At taxi rpms with lots of 'stuff' on, the
field current MIGHT rise to approx 3 amps
but goes down quickly once enegine rpm exceeds
1000.
Lots of folks are stumped and want me to let them
know what is the cause when it=99s solved.
Thank you Bob for your insight and
advice! Please let me know if I can offer you
additional information or clarification.
Pleased to help. Wish we'd started this conversation
a LONG time ago . . .
NOTE TO MEMBERS OF THE LIST: Any time something
misbehaves in your airplane, figure it out sooner
rather than later. That's what the LIST is here
for. Slaying your dragons has two beneficial effects.
It increases reliability (and by extension confidence)
in your airplane. Further, it joins the constellation
of data points from which others may understand and
manage their own projects.
Message 6
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| Subject: | Re: Constructing an automatic RCA video camera feed |
splitter
charlesdavis(at)iuncapped wrote:
> For the question of the number of cameras to cater for ... if you didn't include
the option to change the number of inputs, and had for example 8 available,
then someone who only wants 2 cameras - they could connect each camera to 4
inputs, or 4 cameras could be connected to 2 inputs each. A splitter of some sort
should be able to match the impedances fairly well. or not ?
As we have it planned now, the microcontroller will be programmed with a default
configuration for four cameras. By holding a switch closed during power-up
to enter a programming mode, that setting will be adjustable between one and eight.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473668#473668
Message 7
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| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
I dont think theres an impedance problem - the inputs to the video switch IC are
digital. So yes, I expect it would work fine to connect multiple pic outputs
to one camera select input. You can have a camera that is displayed twice as
often (or twice as long) if you really want, by using 2 PIC outputs connecting
to one video select input. But youd have to solder some green wires on the PCB
to make it happen.
> On Oct 18, 2017, at 4:19 PM, Charles Davis <charlesdavis@iuncapped.co.za> wrote:
>
>
> Hi Guys
>
> For the question of the number of cameras to cater for ... if you didn't include
the option to change the number of inputs, and had for example 8 available,
then someone who only wants 2 cameras - they could connect each camera to 4
inputs, or 4 cameras could be connected to 2 inputs each. A splitter of some sort
should be able to match the impedances fairly well. or not ?
>
> maybe not practical, just a thought that doesn't seem to have been discussed
... and I'd hate for you-all to run out of input
>
> Charles
>
>
>
>
Message 8
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| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
At 07:08 PM 10/18/2017, you wrote:
>
>I don=99t think there=99s an impedance problem -
>the inputs to the video switch IC are digital.
>So yes, I expect it would work fine to connect
>multiple pic outputs to one camera select input.
>You can have a camera that is displayed twice as
>often (or twice as long) if you really want, by
>using 2 PIC outputs connecting to one video
>select input. But you=99d have to solder some
>green wires on the PCB to make it happen.
Unless the outputs are open collector, active low with pull-up resistor,
they cannot be wire-or'd. They have low impedance paths to either
Vcc or Vdd at all times.
Bob . . .
Message 9
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| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
I had in mind that all outputs engage weak pull-ups and are driven
either LOW or HIGH-Z at the PIC. I think that=99s a better way of
driving a CMOS gate from a PIC. Unfortunately I had forgotten my own
advice there aren=99t enough port pins with weak pull-ups in the
16F630, so that would require external discrete pull-up resistors.
However, the 16F18323 is the same 14 pin package as the 16F630, for the
same price (it=99s actually cheaper in bulk), and has configurable
internal pull-ups on all port pins. It has a deeper stack and a bigger
instruction set, and crazy amounts of peripherals. None of which we
actually need, but it just boggles my mind what you can buy for $1.
So if we use that, we can bit-or to our heart=99s delight.
> On Oct 18, 2017, at 10:00 PM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
>
> At 07:08 PM 10/18/2017, you wrote:
<alec@alecmyers.com>
>>
>> I don=C3=A2=C2=C2=99t think there=C3=A2=C2=C2=99s an impedance
problem - the inputs to the video switch IC are digital. So yes, I
expect it would work fine to connect multiple pic outputs to one camera
select input. You can have a camera that is displayed twice as often (or
twice as long) if you really want, by using 2 PIC outputs connecting to
one video select input. But you=C3=A2=C2=C2=99d have to solder some
green wires on the PCB to make it happen.
>
> Unless the outputs are open collector, active low with pull-up
resistor,
> they cannot be wire-or'd. They have low impedance paths to either
> Vcc or Vdd at all times.
>
>
> Bob . . .
>
Message 10
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| Subject: | Re: Constructing an automatic RCA video camera feed |
splitte
Gentlemen, we have a problem. Unless I'm very much mistaken, the CD4066 is not
going to work. I'll be quite happy if someone will tell me I'm wrong, but...
In the CD4066BE datasheet (http://www.ti.com/lit/ds/symlink/cd4066b.pdf), at paragraph 8.1 it says,
CD4066B has four independent digitally controlled analog switches with a bias voltage
of VSS to allow for different voltage levels to be used for low output.
Both the p and the n devices in a given switch are biased on or off simultaneously
by the control signal. As shown in Figure 17, the well of the n-channel
device on each switch is tied to either the input (when the switch is on) or to
VSS (when the switch is off). Thus when the control of the device is low, the
output of the switch goes to VSS while when the control is high the output of
the device goes to VDD.
I read this to mean that we can't tie eight outputs (from two ICs) together into
a common VIDEO OUT bus because one "on" channel will be driving a video signal
into seven others that are sitting at -5V. This IC is four independent analog
switches; tying their outputs together looks like a recipe for silicon smoke.
It gets worse. At paragraph 8.2 (3) it says,
Normal operation control-line biasing: switch on (logic 1), VC = VDD; switch off
(logic 0), VC = VSS. [VC is control voltage.]
So, the switches in this device don't turn fully off at 0V; they must be driven
to Vss (-5V). Obviously, the PIC can't do that. At paragraph 9.2 it presents
a typical application very similar to this effort, and suggests using the CD4054B
CMOS LCD Driver to level-shift 0 to +5V digital signals into -5 to +5V signals.
That's two more 14-DIP ICs, but it doesn't solve the first problem.
I think we're stuck with the AD8184, as it's a proper 4-to-1 multiplexer.
Thoughts?
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473672#473672
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