Today's Message Index:
----------------------
1. 02:47 AM - Re: Re: Constructing an automatic RCA video camera feed splitter (Robert L. Nuckolls, III)
2. 06:03 AM - Re: Constructing an automatic RCA video camera feed splitter (Eric Page)
3. 09:23 AM - Re: Constructing an automatic RCA video camera feed splitter (Airdog77)
4. 11:55 AM - Re: Re: Constructing an automatic RCA video camera feed splitter (Paul A. Fisher)
5. 03:27 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Robert L. Nuckolls, III)
6. 03:40 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Robert L. Nuckolls, III)
7. 03:58 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Alec Myers)
8. 05:35 PM - Re: Constructing an automatic RCA video camera feed splitter (Eric Page)
9. 05:41 PM - Re: Constructing an automatic RCA video camera feed splitter (Eric Page)
10. 09:06 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Robert L. Nuckolls, III)
11. 09:14 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Robert L. Nuckolls, III)
12. 09:26 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Alec Myers)
13. 09:47 PM - Re: Re: Constructing an automatic RCA video camera feed splitter (Alec Myers)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
At 11:28 PM 10/13/2017, you wrote:
>
>I know Wade's specific request for camera switching has been solved,
>but it sounded like the sort of thing that might come up again so I
>thought I'd take a stab at it.
>
>So... here's an alternative for switching cameras to a monitor or
>EFIS input using a couple of voltage regulators and three ICs. All
>components are through-hole. Everything on a single PCB, and no relays.
>
>Reference the attached schematic:
>
>An LM2931 5V linear regulator and a TC7660 charge pump provide +/-5V
>rails to power the circuit. A 555 timer is configured in astable
>mode to provide an output with adjustable period of about 3 to 10
>seconds. This output is fed to the clock input of a CD4022B octal
>counter. The clock signal can be interrupted by a SP3T ON-ON-(ON)
>switch to stop rotation of the cameras or advance them
>manually. Outputs 1-3 of the counter are connected to the logic
>inputs of an AD8184 4:1 video multiplexer such that they cause the
>multiplexer to cycle through its four video inputs, connecting each
>in turn to the output. RCA connectors provide four camera inputs
>and one video output.
>
>LM2931AZ 5V Linear Regulator: http://preview.tinyurl.com/yakjxubl
>TC7660CPA Inverting Charge Pump: http://preview.tinyurl.com/y7n7g6um
>ICM7555IPAZ CMOS Timer: http://preview.tinyurl.com/ybrvnnq2
>CD4022BE Octal Counter: http://preview.tinyurl.com/ycjsa46w
>AD8184ANZ 4:1 Video Multiplexer: http://preview.tinyurl.com/ybozz2nf
>SP3T Toggle Switch: http://preview.tinyurl.com/ybpazcu5
>
>Critiques? Suggestions?
How about replacing the 555 and counter with
a single uC. Paul Fisher can probably craft
the software to emulate these two components
to include the scan, step, rate and hold functions
in one, 8-pin dip device and about 1/20th the
hardware.
Do you want to terminate unused outputs with
dead shorts or 75 ohm resistors? RCA jacks
are more robust than most miniature headphone
jacks. Further, they're available to solder directly
to an ECB. If termination of an unused output is
necessary, a 75 ohm resistor can be installed
in an RCA plug.
Bob . . .
Message 2
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera feed |
splitter
Eliminating the 16-DIP-packaged counter and most of the passives sounds fine to
me. It will certainly shrink the PCB. If you can give me a pin-out for the
uC you propose using, Ill amend the schematic. Ill need to know pin numbers for
Vcc, Gnd, two outputs to the mux, how well read user input for run/hold and
rate, and if an ICSP header is needed. Im guessing you propose the same (PIC12F683?)
used for the recent prop current limiter...
The AD8184 multiplexer has just one output, so I didnt figure a termination resistor
was necessary. The connectors shown actually are RCA jacks, despite the
CAD symbol looking like a headphone...
http://preview.tinyurl.com/ycpmbhj5
They connect the AD8184 inputs to ground with an internal switch contact if no
RCA is plugged in.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473527#473527
Message 3
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera feed |
splitter
Eric,
As an end user --I'll emphasize that aspect since you & Bob are speaking on a cosmic
ethereal plane that this mortal struggles to follow [Wink] -- having another
option is never bad.
I really like the ON-ON-(ON) switch form factor for control. Simple and small,
which is exactly what I need in a Long-EZ. Probably could be incorporated for
most designs, but I'm glad you made note of it.
Regards,
Wade
--------
Airdog
Wade Parton
Building Long-EZ 916WP
www.longezpush.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473536#473536
Message 4
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
Since my name was mentioned, I'll weigh in. I'll be happy to modify the
program Bob mentioned for this function, or more likely, just write a
new one using elements of the one Bob mentioned.
If I understand the AD8184 data sheet, we need to feed A0 and A1 one of
four states - 00, 01, 10, and 11. That's pretty easy to do with just
two pins. If we used the PIC12F683 (mostly because I'm familiar with
it!!), we could do this:
Pin 1 - Vdd
Pin 2 - High order bit to AD8184 (connect to A1)
Pin 3 - Low order bit to AD8184 (connect to A0)
Pin 4 - not used
Pin 5 - Run/Hold switch (pull low to hold)
Pin 6 - Step switch (pull low to immediately switch to the next input)
Pin 7 - Analog voltage (0-5V) to control the speed of switching in Run mode
Pin 8 - Vss
I think you could use the same switch (on-on-(on)) to ground pin 4 in
position 2, and ground pin 6 in the momentary position. Analog voltage
on pin 7 is similar to what you have on the proposed schematic.
Is this what we are looking for? I'll let you and Bob decide on the
hardware components necessary to make it all work, but the PIC software
sounds pretty straight forward.
Paul Fisher
On 10/14/2017 8:00 AM, Eric Page wrote:
>
> Eliminating the 16-DIP-packaged counter and most of the passives sounds fine
to me. It will certainly shrink the PCB. If you can give me a pin-out for the
uC you propose using, Ill amend the schematic. Ill need to know pin numbers
for Vcc, Gnd, two outputs to the mux, how well read user input for run/hold and
rate, and if an ICSP header is needed. Im guessing you propose the same (PIC12F683?)
used for the recent prop current limiter...
>
> The AD8184 multiplexer has just one output, so I didnt figure a termination resistor
was necessary. The connectors shown actually are RCA jacks, despite the
CAD symbol looking like a headphone...
>
> http://preview.tinyurl.com/ycpmbhj5
>
> They connect the AD8184 inputs to ground with an internal switch contact if no
RCA is plugged in.
>
> Eric
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=473527#473527
>
>
Message 5
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
At 08:00 AM 10/14/2017, you wrote:
>
>Eliminating the 16-DIP-packaged counter and most
>of the passives sounds fine to me. It will
>certainly shrink the PCB. If you can give me a
>pin-out for the uC you propose using, I=99ll amend the schematic.
See attached
> I=99ll need to know pin numbers for Vcc, Gnd,
> two outputs to the mux, how we=99ll read user
> input for run/hold and rate, and if an ICSP
> header is needed. I=99m guessing you propose
> the same (PIC12F683?) used for the recent prop current limiter...
Yeah . . . only 'case they're cheap and we got lots
of them!
Probably wouldn't fuss with ICSP, just put the chip
in a socket. This lets a user drop a new chip
into a fielded assembly should any future feature be
desired/necessary.
The sequencing software could be set up to default to
either SCAN or STEP at power up. Your choice. If the default
is STEP, then Channel A input is the first up.
Momentary depression of the switch to STEP would advance
to next channel in sequence. Momentary depression to SCAN
would initiate steps through the four inputs at a rate
commanded by the potentiometer. Setting a rate of
say 3 to 10 seconds for zero to 5 volts seems a
good starting point.
I didn't suggest any DO-160 like protections for
inputs to the command pins. If the switch is
on the board it's not needed. If off the board,
extending the lines in a shielded-twisted pair
would offer plenty good prophylactics for our
environment.
>The AD8184 multiplexer has just one output, so I
>didn=99t figure a termination resistor was
>necessary. The connectors shown actually are
>RCA jacks, despite the CAD symbol looking like a headphone...
Aha! Been there . . . fiddled with several
canned libraries for about an hour each
before I dumped them all and crafted my
own.
>http://preview.tinyurl.com/ycpmbhj5
>
>They connect the AD8184 inputs to ground with an
>internal switch contact if no RCA is plugged in.
Understand.
I propose we make this another open source program like
the wig-wag was . . . I'll be pleased to set up a folder
to host all the work product.
Bob . . .
Message 6
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
At 01:50 PM 10/14/2017, you wrote:
<paulf@hughes.net>
>
>Since my name was mentioned, I'll weigh
>in.=C2 I'll be happy to modify the program Bob
>mentioned for this function, or more likely,
>just write a new one using elements of the one Bob mentioned.
>
>If I understand the AD8184 data sheet, we need
>to feed A0 and A1 one of four states - 00, 01,
>10, and 11.=C2 That's pretty easy to do with just
>two pins.=C2 If we used the PIC12F683 (mostly
>because I'm familiar with it!!), we could do this:
>Pin 1 - Vdd
>Pin 2 - High order bit to AD8184 (connect to A1)
>Pin 3 - Low order bit to AD8184 (connect to A0)
>Pin 4 - not used
>Pin 5 - Run/Hold switch (pull low to hold)
>Pin 6 - Step switch (pull low to immediately switch to the next input)
>Pin 7 - Analog voltage (0-5V) to control the speed of switching in Run mode
>Pin 8 - Vss
>
>I think you could use the same switch
>(on-on-(on)) to ground pin 4 in position 2, and
>ground pin 6 in the momentary position.=C2 Analog
>voltage on pin 7 is similar to what you have on the proposed schematic.
>
>Is this what we are looking for?=C2 I'll let you
>and Bob decide on the hardware components
>necessary to make it all work, but the PIC
>software sounds pretty straight forward.
>
>Paul Fisher
Our 'ships' passed in the night. I was going
to suggest that you take the sketch I posted
and adjust to what makes sense both from
a software and layout perspective.
Bob . . .
Message 7
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
Bob
Do you know how much extra work it takes to make a PIC meet DO-160?
> On Oct 14, 2017, at 6:24 PM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
>
> At 08:00 AM 10/14/2017, you wrote:
<edpav8r@yahoo.com>
>>
>> Eliminating the 16-DIP-packaged counter and most of the passives
sounds fine to me. It will certainly shrink the PCB. If you can give
me a pin-out for the uC you propose using, I=C3=A2=C2=C2=99ll amend
the schematic.
>
> See attached
>
>> I=C3=A2=C2=C2=99ll need to know pin numbers for Vcc, Gnd, two
outputs to the mux, how we=C3=A2=C2=C2=99ll read user input for
run/hold and rate, and if an ICSP header is needed. I=C3=A2=C2=C2=99m
guessing you propose the same (PIC12F683?) used for the recent prop
current limiter...
>
> Yeah . . . only 'case they're cheap and we got lots
> of them!
>
> Probably wouldn't fuss with ICSP, just put the chip
> in a socket. This lets a user drop a new chip
> into a fielded assembly should any future feature be
> desired/necessary.
>
> The sequencing software could be set up to default to
> either SCAN or STEP at power up. Your choice. If the default
> is STEP, then Channel A input is the first up.
>
> Momentary depression of the switch to STEP would advance
> to next channel in sequence. Momentary depression to SCAN
> would initiate steps through the four inputs at a rate
> commanded by the potentiometer. Setting a rate of
> say 3 to 10 seconds for zero to 5 volts seems a
> good starting point.
>
> I didn't suggest any DO-160 like protections for
> inputs to the command pins. If the switch is
> on the board it's not needed. If off the board,
> extending the lines in a shielded-twisted pair
> would offer plenty good prophylactics for our
> environment.
>
>
>> The AD8184 multiplexer has just one output, so I didn=C3=A2=C2=C2=99
t figure a termination resistor was necessary. The connectors shown
actually are RCA jacks, despite the CAD symbol looking like a
headphone...
>
> Aha! Been there . . . fiddled with several
> canned libraries for about an hour each
> before I dumped them all and crafted my
> own.
>
>
>> http://preview.tinyurl.com/ycpmbhj5
<http://preview.tinyurl.com/ycpmbhj5>
>>
>> They connect the AD8184 inputs to ground with an internal switch
contact if no RCA is plugged in.
>
> Understand.
>
> I propose we make this another open source program like
> the wig-wag was . . . I'll be pleased to set up a folder
> to host all the work product.
>
> Bob . . .
>
> <Video Sequencer.pdf>
Message 8
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera feed |
splitter
nuckolls.bob(at)aeroelect wrote:
> I propose we make this another open source program like the wig-wag was . . .
I'll be pleased to set up a folder to host all the work product.
Great. I kinda figured we were doing an open-source effort. With that in mind,
I had a good think about this while slogging for six hours against 145-knot
headwinds this morning...
I think there are a few issues that argue against changing to a PIC microcontroller
in this project. Wade alluded to the first one in his post this morning
(which, along with one other from Clayton, has disappeared from the server) when
he joked about the details being over his head:
- It would make the project considerably less accessible to many builders. Anyone
without a hardware programmer and the Microchip IDE software will either have
to get them, then find the code to download and learn how to program the PIC,
or buy a PIC with the code already loaded. On the other hand, anyone pretty
much anywhere with a soldering iron and minimal skill can put my design together
for as long as its jellybean components are available.
- Software updates will require removing the unit from service, removing the PIC
to send for reprogramming, or buying a new PIC to replace it.
- A PIC won't simplify the user interface. We still need a switch for the run/hold/step
function and a knob to adjust scan rate. Perhaps a system using buttons
or a rotary encoder could be devised, but it would probably be less intuitive
than the switch and knob.
- If a PIC could replace the $7 video multiplexer chip, you could make a good case
for lowering cost, but we're talking about replacing a couple of 50 to 80-cent
jellybeans and a few passives that are tens of cents each -- about $3 total.
Can anyone deliver a programmed PIC for $3 and make it worth their trouble?
- The size of the PCB is going to be driven largely by the five RCA jacks, so deleting
a 16-DIP and a few passives probably won't shrink the board appreciably.
I think this is a case where a microcontroller may be overkill, given that suitable
cheap ICs are readily available. Given the simplicity of the problem, wouldn't
it make more sense to keep the solution simple?
Thoughts?
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473555#473555
Message 9
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera feed |
splitter
Wade,
Question: do you want to be able to adjust the scan rate as a matter of routine
operation (i.e. with a panel-mounted knob), or do you envision setting the rate
where you like it at installation, and leaving it alone?
The answer will dictate whether we put a small trimmer potentiometer on the circuit
board or design for a larger panel-mounted potentiometer and knob.
Eric
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473556#473556
Message 10
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
At 07:38 PM 10/14/2017, you wrote:
>
>Wade,
>
>Question: do you want to be able to adjust the scan rate as a matter
>of routine operation (i.e. with a panel-mounted knob), or do you
>envision setting the rate where you like it at installation, and
>leaving it alone?
I was thinking a 10-turn pot on the board . . . probably
left in place after some in-service experience . . .
>The answer will dictate whether we put a small trimmer potentiometer
>on the circuit board or design for a larger panel-mounted
>potentiometer and knob.
How about pads for extending the pot leads out
on a shielded pair, or simply installing a couple
of resistors to set the rate to some pre-determined
value. We could publish a table of resistors versus
rates to minimize the fiddling.
Bob . . .
Message 11
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
At 07:32 PM 10/14/2017, you wrote:
>
>
>nuckolls.bob(at)aeroelect wrote:
> > I propose we make this another open source program like the
> wig-wag was . . . I'll be pleased to set up a folder to host all
> the work product.
>
>
>Great. I kinda figured we were doing an open-source effort. With
>that in mind, I had a good think about this while slogging for six
>hours against 145-knot headwinds this morning...
>
>I think there are a few issues that argue against changing to a PIC
>microcontroller in this project. Wade alluded to the first one in
>his post this morning (which, along with one other from Clayton, has
>disappeared from the server) when he joked about the details being
>over his head:
>
>- It would make the project considerably less accessible to many
>builders. Anyone without a hardware programmer and the Microchip
>IDE software will either have to get them, then find the code to
>download and learn how to program the PIC, or buy a PIC with the
>code already loaded. On the other hand, anyone pretty much anywhere
>with a soldering iron and minimal skill can put my design together
>for as long as its jellybean components are available.
True . . . your choice. On the flip side,
I'll offer programmed chips at cost plus
postage . . . probably less than $2 each.
The same constraints exist for the ECB itself.
My usual source for boards is ExpressPCB. I
can see this project fitting two ship-sets
per 'miniboard' x 3 for the standard minimum
order. This means that an individual builder
would have to purchase 6 ecbs and hope to sell/
trade off the excess.
It might be more practical to offer AEC 'kits'
of a programmed chip and an ECB which gets around
both the ECB batch costs AND chip programming.
>- Software updates will require removing the unit from service,
>removing the PIC to send for reprogramming, or buying a new PIC to replace it.
Naw, never return a chip . . . just pitch it
and replace it.
>- A PIC won't simplify the user interface. We still need a switch
>for the run/hold/step function and a knob to adjust scan
>rate. Perhaps a system using buttons or a rotary encoder could be
>devised, but it would probably be less intuitive than the switch and knob.
agreed
>- If a PIC could replace the $7 video multiplexer chip, you could
>make a good case for lowering cost, but we're talking about
>replacing a couple of 50 to 80-cent jellybeans and a few passives
>that are tens of cents each -- about $3 total. Can anyone deliver a
>programmed PIC for $3 and make it worth their trouble?
don't know about worth the trouble . . . but yeah,
I can beat the $3 by some good percentage.
>- The size of the PCB is going to be driven largely by the five RCA
>jacks, so deleting a 16-DIP and a few passives probably won't shrink
>the board appreciably.
>
>I think this is a case where a microcontroller may be overkill,
>given that suitable cheap ICs are readily available. Given the
>simplicity of the problem, wouldn't it make more sense to keep the
>solution simple?
>Thoughts?
>
>Eric
Either way works my friend . . . your choice.
Bob . . .
Message 12
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
Random thoughts from someone with 15 years experience designing and programming
PIC projects:
> - It would make the project considerably less accessible to many builders. Anyone
without a hardware programmer and the Microchip IDE software will either
have to get them, then find the code to download and learn how to program the
PIC, or buy a PIC with the code already loaded.
> Can anyone deliver a programmed PIC for $3 and make it worth their trouble?
Yep. Arizona Microchip themselves, will. Upload the code, and theyll send you programmed
parts direct from their factory in Thailand.
If youre going to the trouble of ordering a custom PCB, then a custom PIC really
isnt much extra bother.
> - Software updates will require removing the unit from service, removing the
PIC to send for reprogramming, or buying a new PIC to replace it.
Its 2017. Never socket a PIC. Solder it to the PCB for reliability and use the
ICSP header to program and reprogram, until you have the software right. If you
goof and let out the magic smoke throw away the $1 PCB and $0.40 PIC and grab
another one. Use a SMT part to save the cost of drilling the PCB. Theyre not
*that* hard to solder. In fact if you design it right you dont need a drilled
PCB at all.
> - A PIC won't simplify the user interface. We still need a switch for the run/hold/step
function and a knob to adjust scan rate. Perhaps a system using buttons
or a rotary encoder could be devised, but it would probably be less intuitive
than the switch and knob.
A one-button user interface is trivial with a PIC: press to advance to the next
camera, press-and-hold to resume scanning. If you want to get fancy, double-press,
double-press-and-hold are all available, for fast scan, slow scan, whatever
else you want. Once you paid for the PIC you might as well load the code up
with features. It doesnt cost any extra. If Paul doesnt want the challenge Ill
write it for you.
>
On the subject of adjusting the scanning speed: use the extra pins of whatever
PIC you choose for selecting a scan rate. Get rid of extra resistors and other
unnecessary components!
> On Oct 14, 2017, at 8:32 PM, Eric Page <edpav8r@yahoo.com> wrote:
>
>
>
> nuckolls.bob(at)aeroelect wrote:
>> I propose we make this another open source program like the wig-wag was . .
. I'll be pleased to set up a folder to host all the work product.
>
>
> Great. I kinda figured we were doing an open-source effort. With that in mind,
I had a good think about this while slogging for six hours against 145-knot
headwinds this morning...
>
> I think there are a few issues that argue against changing to a PIC microcontroller
in this project. Wade alluded to the first one in his post this morning
(which, along with one other from Clayton, has disappeared from the server)
when he joked about the details being over his head:
>
> - It would make the project considerably less accessible to many builders. Anyone
without a hardware programmer and the Microchip IDE software will either
have to get them, then find the code to download and learn how to program the
PIC, or buy a PIC with the code already loaded. On the other hand, anyone pretty
much anywhere with a soldering iron and minimal skill can put my design together
for as long as its jellybean components are available.
>
> - Software updates will require removing the unit from service, removing the
PIC to send for reprogramming, or buying a new PIC to replace it.
>
> - A PIC won't simplify the user interface. We still need a switch for the run/hold/step
function and a knob to adjust scan rate. Perhaps a system using buttons
or a rotary encoder could be devised, but it would probably be less intuitive
than the switch and knob.
>
> - If a PIC could replace the $7 video multiplexer chip, you could make a good
case for lowering cost, but we're talking about replacing a couple of 50 to 80-cent
jellybeans and a few passives that are tens of cents each -- about $3 total.
Can anyone deliver a programmed PIC for $3 and make it worth their trouble?
>
> - The size of the PCB is going to be driven largely by the five RCA jacks, so
deleting a 16-DIP and a few passives probably won't shrink the board appreciably.
>
> I think this is a case where a microcontroller may be overkill, given that suitable
cheap ICs are readily available. Given the simplicity of the problem,
wouldn't it make more sense to keep the solution simple?
>
> Thoughts?
>
> Eric
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=473555#473555
>
>
>
>
>
>
>
>
>
Message 13
| INDEX | Back to Main INDEX |
| PREVIOUS | Skip to PREVIOUS Message |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | Re: Constructing an automatic RCA video camera |
feed splitter
If you use a PIC, you could (trivially) do the following:
Hold the button down for ten seconds to enter programming mode. Press the button
briefly x times to set the scan period at x seconds. Press the button for two
seconds to exit programming mode.
No need for resistors at all.
> On Oct 14, 2017, at 8:38 PM, Eric Page <edpav8r@yahoo.com> wrote:
>
>
> Wade,
>
> Question: do you want to be able to adjust the scan rate as a matter of routine
operation (i.e. with a panel-mounted knob), or do you envision setting the
rate where you like it at installation, and leaving it alone?
>
> The answer will dictate whether we put a small trimmer potentiometer on the circuit
board or design for a larger panel-mounted potentiometer and knob.
>
> Eric
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=473556#473556
>
>
>
>
>
>
>
>
>
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|