Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

IVO Prop current limiter
Goto page Previous  1, 2, 3, 4  Next
 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Sun Jul 09, 2017 8:26 am    Post subject: IVO Prop current limiter Reply with quote

At 12:45 PM 7/8/2017, you wrote:
Quote:
Sorry - defective iPhones and all that.

Possible simplifications to consider:

- If you’re using a PIC maybe you could dispense with the current limiter. If you sense the current the PIC can send the FET high impedance within a few microseconds.

The motor's current profile is rather trashy.
Without active current limiting, you'll have
motor inrush currents during spin-up.

As I recall the mechanical details of this
product, the prop-pitch mechanism has soft
stops that will compress as the mechanism
approaches limits causing the motor current
to ramp up toward stall current.

The original design goal was to tolerate a
deliberate opening of the prop pitch circuit
breaker . . . which is a rather slow device . . .
on the order of hundreds of milliseconds.

All this electron/silicon herding does is
get us a more predictable, solid state
replacment for the thermal breaker. The
current limiter adds one transistor
and one resistor and offers a predictable
upper bound on stall current.


Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
paulf(at)hughes.net
Guest





PostPosted: Sun Jul 09, 2017 5:43 pm    Post subject: IVO Prop current limiter Reply with quote

Eric - See Bob's redesign.  I was in the process of writing code for your drawing when Bob sent his note. I now have a version of the software written (but not tested!) for both versions of the hardware, so you just need to let me know which one you want to pursue.
Paul

On 7/9/2017 11:06 AM, Robert L. Nuckolls, III wrote:

Quote:
At 08:59 AM 7/8/2017, you wrote:

Quote:
The software that Bob describes would be pretty simple to write for the PIC12F683 chip, the same chip we used for the wig-wag open source project.  I'll volunteer to contribute the software if someone wants to pursue Bob's hardware design using a PIC chip instead of the Arduino as an open source project.

  I'm up to my eyeballs in a couple of development
  efforts along with juggling domestic duties . . .
  but if someone wants to brassboard this project,
  I'll volunteer to package it into a readily
  duplicated product.

  I've posted a proposed schematic of the controller
  at http://tinyurl.com/ybbtw6dp

  A minimalist approach to packaging would
  look something like this. The fat power transistor
  would be on the bottom, heat transfer surface down.
  This would facilitate using airframe for heat-sinking
  like our schottky e-bus diode did. The connector
  would be 15 pin.  The ECB footprint would be about
  1.25 x 1.75 inches.  The 'kit' would look something
  like this except that the 700-2-7 switch is
  missing.




[img]cid:part2.D1EE81D6.29A720F5(at)hughes.net[/img]


  Oh yeah, had a gray-matter fart while crafting the
  schematic. The software can get MUCH simpler.

  On power up, the initialization CLEARS the LIMIT
  LATCH and removes gate drive from the clamping
  fet.

  The analog input is monitored for amplitude greater
  than 0.5 volts; greater than 0.5 seconds whereupon
  the LIMIT LATCH is SET, gate of clamp fet goes
  high and removed drive from the current limit fet.

  An excursion below 0.5v will reset the LIMIT
  TIMER.

  After limit time out, the condition is sustained
  until next power-down/power-up event.

  I need to keep my head down on some more pressing
  tasks for the next 10 days or so. You guys can
  shepherd this along in the mean time. 

  Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



3daa086.jpg
 Description:
 Filesize:  654.09 KB
 Viewed:  16190 Time(s)

3daa086.jpg


Back to top
Eric Page



Joined: 15 Feb 2017
Posts: 241

PostPosted: Sun Jul 09, 2017 6:06 pm    Post subject: Re: IVO Prop current limiter Reply with quote

paulf(at)hughes.net wrote:
Eric - See Bob's redesign. I was in the process of writing code for your drawing when Bob sent his note. I now have a version of the software written (but not tested!) for both versions of the hardware, so you just need to let me know which one you want to pursue.

Paul


Paul,

I was just composing a post to ask Bob a couple of questions in that vein. Stand by while I sort that out and we'll press ahead shortly.

One question for you: am I correct in assuming that PIC outputs are push-pull (that is, when low, they actively pull to ground)?

Thanks,

Eric


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Sun Jul 09, 2017 7:12 pm    Post subject: IVO Prop current limiter Reply with quote

At 09:06 PM 7/9/2017, you wrote:
Quote:
--> AeroElectric-List message posted by: "Eric Page" <edpav8r(at)yahoo.com>


paulf(at)hughes.net wrote:
> Eric - See Bob's redesign. I was in the process of writing code for your drawing when Bob sent his note. I now have a version of the software written (but not tested!) for both versions of the hardware, so you just need to let me know which one you want to pursue.
>
> Paul


Paul,

I was just composing a post to ask Bob a couple of questions in that vein. Stand by while I sort that out and we'll press ahead shortly.

One question for you: am I correct in assuming that PIC outputs are push-pull (that is, when low, they actively pull to ground)?


The general purpose outputs are active pull-up/pull-down.

A bit more robust in the pull down as I recall . . .

Yes the output will pull down to less than 0.6 v with a 8.5mA
source.


[img]cid:7.1.0.9.0.20170709220122.020de7f0(at)aeroelectric.com.0[/img]


Input will pull up to within 0.7 of Vdd with a 3.0mA sink



[img]cid:7.1.0.9.0.20170709220122.020de7f0(at)aeroelectric.com.1[/img]



Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



63b3c93.jpg
 Description:
 Filesize:  36.35 KB
 Viewed:  16154 Time(s)

63b3c93.jpg



63b3cf0.jpg
 Description:
 Filesize:  33.86 KB
 Viewed:  16154 Time(s)

63b3cf0.jpg


Back to top
Eric Page



Joined: 15 Feb 2017
Posts: 241

PostPosted: Sun Jul 09, 2017 7:33 pm    Post subject: Re: IVO Prop current limiter Reply with quote

Paul / Bob,

One more question: with respect to GP3/MCLR, should it be left floating, pulled up to Vdd, or have an RC power-on-reset circuit?

Eric


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
Eric Page



Joined: 15 Feb 2017
Posts: 241

PostPosted: Sun Jul 09, 2017 7:58 pm    Post subject: Re: IVO Prop current limiter Reply with quote

Bob,

I have a few questions/comments about your drawing (http://tinyurl.com/ybbtw6dp):

A. The big current limit MOSFET is going to be in one of three states:

1. Fully on: The pilot has moved the switch, the PIC is powered on, and LIMIT LATCH is released, allowing motor drive voltage to pull up the MOSFET's gate through the 1k resistor. Rds(on) is at minimum value and dissipation is negligible (less than 1/4W).

2. Fully off: The PIC sees >=0.5V for >0.5 sec on LIMIT SENSE. LIMIT LATCH goes high, turning on the 2N7000, which pulls the MOSFET's gate to ground. Dissipation is zero. [0.5V = 7.5A motor current.]

3. Linear region: Motor current has spiked to >9A, causing the sense resistors and 2N3904 to regulate the MOSFET's gate to hold the 9A level. Dissipation is high, but LIMIT LATCH will trip in 0.5 sec max, dropping it to zero.

So, it seems to me that unless we worry that the pilot will continue to cycle the switch in the stalled direction with the limit light illuminated, we don't need to be too concerned with heat sinking the MOSFET. Your thoughts?

B. You're powering the PIC from the motor drive voltage, but you mentioned in your reply to Alec Myers that this is likely to be a "trashy" rail. Your new schematic only uses this rail to power the PIC and pull up the current limit MOSFET's gate. Could we eliminate the two 1N4001 diodes and the wires linking them to the switch, and instead bring in a constant supply on a single wire from the bus side of the switch? Is there some benefit to turning the PIC on and off with the prop switch?

C. Your current sense resistor is shown rated at 2W. I've calculated 2.4W dissipation at 6A motor current, rising to 3.75W at 7.5A and 5.4W at 9A. I used three 0.2R 3W resistors in parallel to get 0.066667 ohms at 9W.

D. The 2N7000 that switches the TRAVEL LIMIT light can tolerate Vds=Vdg=60V. What is the 24V Zener diode doing?

Cheers,

Eric


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Mon Jul 10, 2017 4:18 am    Post subject: IVO Prop current limiter Reply with quote

At 10:59 PM 7/9/2017, you wrote:
Quote:
--> AeroElectric-List message posted by: "Eric Page" <edpav8r(at)yahoo.com>

Bob,

I have a few questions/comments about your drawing ( http://tinyurl.com/ybbtw6dp ( http://tinyurl.com/ybbtw6dp)):


A. The big current limit MOSFET is going to be in one of three states:

1. Fully on: The pilot has moved the switch, the PIC is powered on, and LIMIT LATCH is released, allowing motor drive voltage to pull up the MOSFET's gate through the 1k resistor. Rds(on) is at minimum value and dissipation is negligible (less than 1/4W).

yes


Quote:
2. Fully off: The PIC sees >=0.5V for >0.5 sec on LIMIT SENSE. LIMIT LATCH goes high, turning on the 2N7000, which pulls the MOSFET's gate to ground. Dissipation is zero. [0.5V = 7.5A motor current.]

yes


Quote:
3. Linear region: Motor current has spiked to >9A, causing the sense resistors and 2N3904 to regulate the MOSFET's gate to hold the 9A level. Dissipation is high, but LIMIT LATCH will trip in 0.5 sec max, dropping it to zero.

yes . . .


Quote:
So, it seems to me that unless we worry that the pilot will continue to cycle the switch in the stalled direction with the limit light illuminated, we don't need to be too concerned with heat sinking the MOSFET. Your thoughts?

the fat fet needs some heat sinking but
just enough thermal mass to keep the silicon in
limits during the trip time-out interval. Generally,
a metallic mounting base is enough. There's a cartoon
of the board layout below . . . the fet is on the bottom
of the board with heat-sink surface facing down to
contact mounting surface. This is something to be
explored in development . . . see if you can deliberately
smoke one!



Quote:
B. You're powering the PIC from the motor drive voltage, but you mentioned in your reply to Alec Myers that this is likely to be a "trashy" rail. Your new schematic only uses this rail to power the PIC and pull up the current limit MOSFET's gate. Could we eliminate the two 1N4001 diodes and the wires linking them to the switch, and instead bring in a constant supply on a single wire from the bus side of the switch? Is there some benefit to turning the PIC on and off with the prop switch?

The current signal will be trashy but the supply
voltage comes from the bus (low impedance source).
The precision shunt zener combined with the 10uf
Vdd capacitor will offer us a very clean source
of power for the pic.



Quote:
C. Your current sense resistor is shown rated at 2W. I've calculated 2.4W dissipation at 6A motor current, rising to 3.75W at 7.5A and 5.4W at 9A. I used three 0.2R 3W resistors in parallel to get 0.066667 ohms at 9W.

Good eye, I wired 4 x .24 ohms in parallel as you can see
below . . . while marginal for continuous operation
at this dissipation level, half-second intervals
will be no sweat . . . or should I say no smoke?



Quote:
D. The 2N7000 that switches the TRAVEL LIMIT light can tolerate Vds=Vdg=60V. What is the 24V Zener diode doing?
Yeah . . . probably not really necessary . . . just
a carry-over from my DO-160 qualification days
when I was obligated to put some protection on all i/o
lines designed to clamp off very low energy, 300v
spikes. In practice, that zener can probably
be left off.

Here's how the board layout shaped up . . .

[img]cid:.0[/img]



Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



82f36b4.jpg
 Description:
 Filesize:  84.19 KB
 Viewed:  16127 Time(s)

82f36b4.jpg


Back to top
alec(at)alecmyers.com
Guest





PostPosted: Mon Jul 10, 2017 4:38 am    Post subject: IVO Prop current limiter Reply with quote

If for any reason the PIC crashes (cosmic rays? It does happen) when the motor reaches its limit the FET will sit in an intermediate impedance state dissipating high power for an indeterminate length of time, possibly long enough to be emit the magic smoke. Without adequate heat sinking for the FET the PIC software should use appropriate watchdog timers and brown-out protection to minimize this risk. This is more of a problem if the PIC is powered from the 12v rail because it will be operational for effectively unlimited time before the timer is called into operation. If the PIC is powered from the motor command voltage this risk is much reduced as the PIC run time begins only when the motor is first powered.
The motor supply for sure is going to be trashy but PICs are designed to run in very unclean environments. I agree that clean rails are better than dirty ones but you could clean the motor supply rail with a simple RC network too.
Quote:
On Jul 10, 2017, at 8:17 AM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:
3. Linear region: Motor current has spiked to >9A, causing the sense resistors and 2N3904 to regulate the MOSFET's gate to hold the 9A level. Dissipation is high, but LIMIT LATCH will trip in 0.5 sec max, dropping it to zero.
yes . . .



- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
ceengland7(at)gmail.com
Guest





PostPosted: Mon Jul 10, 2017 6:00 am    Post subject: IVO Prop current limiter Reply with quote

Just out of curiosity, wouldn't a Polyfuse, similar to what's used in a car's electric window circuit, do what you're after? They're available up to 14 A ratings.
http://www.mouser.com/Search/Refine.aspx?Keyword=polyfuse


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
nuckolls.bob(at)aeroelect
Guest





PostPosted: Mon Jul 10, 2017 6:22 am    Post subject: IVO Prop current limiter Reply with quote

At 07:36 AM 7/10/2017, you wrote:
Quote:
If for any reason the PIC crashes (cosmic rays? It does happen) when the motor reaches its limit the FET will sit in an intermediate impedance state dissipating high power for an indeterminate length of time, possibly long enough to be emit the magic smoke.

That's true . . . but if we were going to do
a reliability study for a PIC chip in a
high hazard application, we would find
that the chip itself is probably good for
10 to the minus bazzilion failures per
operating hour. Given that this chip operates
only seconds per flight hour, I think a
high degree of confidence is not misguided.

Quote:
Without adequate heat sinking for the FET the PIC software should use appropriate watchdog timers and brown-out protection to minimize this risk.

. . . but if the chip goes TU . . . what's
the probability that built in safeguards are
operating?

Quote:
This is more of a problem if the PIC is powered from the 12v rail because it will be operational for effectively unlimited time before the timer is called into operation. If the PIC is powered from the motor command voltage this risk is much reduced as the PIC run time begins only when the motor is first powered.

Exactly . . .

Quote:
The motor supply for sure is going to be trashy but PICs are designed to run in very unclean environments. I agree that clean rails are better than dirty ones but you could clean the motor supply rail with a simple RC network too.

The power supply configuration depicted has
been used on products fully qualified under
DO160 stresses for trash. The 5v rail
is very precise, rigid and clean.


Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
paulf(at)hughes.net
Guest





PostPosted: Mon Jul 10, 2017 6:47 am    Post subject: IVO Prop current limiter Reply with quote

For this application, if we go with Bob's most recent design, I suggest
we leave GP3/MCLR float. Unless we plan to use the MCLR function, I'll
disable it in software making GP3 a "normal" input (I put normal in
quotes because I can't do a weak pull up on GP3). I've had issues in the
past with that pin unless I software disable it.

Bob answered your other questions, and way better than I could!!

Paul
On 7/9/2017 10:33 PM, Eric Page wrote:
Quote:


Paul,

One more question: with respect to GP3/MCLR, should it be left floating, pulled up to Vdd, or have an RC power-on-reset circuit?

Eric


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=470839#470839




- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
nuckolls.bob(at)aeroelect
Guest





PostPosted: Mon Jul 10, 2017 6:53 am    Post subject: IVO Prop current limiter Reply with quote

At 08:59 AM 7/10/2017, you wrote:
Quote:
Just out of curiosity, wouldn't a Polyfuse, similar to what's used in a car's electric window circuit, do what you're after? They're available up to 14 A ratings.
http://www.mouser.com/Search/Refine.aspx?Keyword=polyfuse


Probably. The advantage here is the limit annunciator
light that would be very slow if it didn't illuminate
until the pollyfuse warms up and operates.

The disadvantage is that assuming you DID hold a command
at the limit until the fuse operates, you would not be
able to drive out of that limit until the fuse cools
off . . .

We looked at polyfuses on three separate occasions
at Lear and Beech over the years . . . aside from
exploiting the benefits of inrush limiting on incandescent
lamps (NTC devices), there wasn't enough going for them
to encourage a development program. They're designed
to install inside some piece of hardware. We would
have to enclose and terminate the things to make them
an airframe component.

To be sure, the price is right!



Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
alec(at)alecmyers.com
Guest





PostPosted: Mon Jul 10, 2017 7:02 am    Post subject: IVO Prop current limiter Reply with quote

Maybe I’m misunderstanding: If I read it right, the design calls for the PIC to run whenever the bus is powered, i.e. during the whole flight. PICs do crash and suffer brownouts: that’s why they have built-in brownout protection and watchdog timers. If these events only happened every bazillion years, Arizona Microchip wouldn’t waste the silicon.
So when you say seconds per flight: the timer is called for for only seconds per flight, but the PIC is running through a do-nothing loop for the entirety of the rest of the flight. If that loop locks up at any time (and it will do so invisibly) then the timer won’t operate when called for. Again - if watchdog timers were *not* needed, the facility would not be embedded in the silicon.

Quote:
On Jul 10, 2017, at 10:22 AM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
At 07:36 AM 7/10/2017, you wrote:
Quote:
If for any reason the PIC crashes (cosmic rays? It does happen) when the motor reaches its limit the FET will sit in an intermediate impedance state dissipating high power for an indeterminate length of time, possibly long enough to be emit the magic smoke.
That's true . . . but if we were going to do a reliability study for a PIC chip in a high hazard application, we would find that the chip itself is probably good for 10 to the minus bazzilion failures per operating hour. Given that this chip operates only seconds per flight hour, I think a high degree of confidence is not misguided.
Quote:
Without adequate heat sinking for the FET the PIC software should use appropriate watchdog timers and brown-out protection to minimize this risk.
. . . but if the chip goes TU . . . what's the probability that built in safeguards are operating?
Quote:
This is more of a problem if the PIC is powered from the 12v rail because it will be operational for effectively unlimited time before the timer is called into operation. If the PIC is powered from the motor command voltage this risk is much reduced as the PIC run time begins only when the motor is first powered.
Exactly . . .
Quote:
The motor supply for sure is going to be trashy but PICs are designed to run in very unclean environments. I agree that clean rails are better than dirty ones but you could clean the motor supply rail with a simple RC network too.
The power supply configuration depicted has been used on products fully qualified under DO160 stresses for trash. The 5v rail is very precise, rigid and clean.
Bob . . .



- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
Eric Page



Joined: 15 Feb 2017
Posts: 241

PostPosted: Mon Jul 10, 2017 7:17 am    Post subject: Re: IVO Prop current limiter Reply with quote

Thanks for all the quick replies. I think I have all the info I need to bang out a second revision to this schematic and wiring diagram. I'll see if I can get it done today. Then if everyone's happy with it, I'll start on a PCB layout.

Eric


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Mon Jul 10, 2017 8:11 am    Post subject: IVO Prop current limiter Reply with quote

At 10:02 AM 7/10/2017, you wrote:
Quote:
Maybe I’m misunderstanding: If I read it right, the design calls for the PIC to run whenever the bus is powered, i.e. during the whole flight.


No, only while the command switch is calling
for change of pitch.

Quote:
PICs do crash and suffer brownouts: that’s why they have built-in brownout protection and watchdog timers. If these events only happened every bazillion years, Arizona Microchip wouldn’t waste the silicon.

Brownouts are EXTERNALLY generated events
caused by sagging supply voltage. The power
supply configuration shown will maintain operable
Vdd levels on the PIC to LESS than 10V on the
ship's bus . . . which means that the airplane
has a lot bigger problems than a malfunctioning
prop-pitch controller.

Quote:
So when you say seconds per flight: the timer is called for for only seconds per flight, but the PIC is running through a do-nothing loop for the entirety of the rest of the flight.

Not so. Vdd is generated through a diode OR
input that routes MOTOR(+) power to the
regulator . . . power that is present only
while the switch is calling for prop pitch
motion.


Quote:
If that loop locks up at any time (and it will do so invisibly) then the timer won’t operate when called for. Again - if watchdog timers were *not* needed, the facility would not be embedded in the silicon.

Do the FMEA . . . suppose you were tasked with
CREATING a situation that would confuse/damage
the PIC, how would you go about it? Can you
demonstrate the condition(s) on the bench?

Assuming such an experiment is successful, what
is the probability of that condition occurring
in the aircraft?




Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
nuckolls.bob(at)aeroelect
Guest





PostPosted: Mon Jul 10, 2017 8:20 am    Post subject: IVO Prop current limiter Reply with quote

At 09:43 AM 7/10/2017, you wrote:
Quote:
--> AeroElectric-List message posted by: "Paul A. Fisher" <paulf(at)hughes.net>

For this application, if we go with Bob's most recent design, I suggest we leave GP3/MCLR float. Unless we plan to use the MCLR function, I'll disable it in software making GP3 a "normal" input (I put normal in quotes because I can't do a weak pull up on GP3). I've had issues in the past with that pin unless I software disable it.

Bob answered your other questions, and way better than I could!!

Paul


I've updated the schematic with pin numbers and chip
labels that conform to the ECB layout below.

ECB files are posted also . . .

See http://tinyurl.com/yby3waw6



[img]cid:7.1.0.9.0.20170710111139.05cadfa0(at)aeroelectric.com.0[/img]



Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



90cf47b.jpg
 Description:
 Filesize:  367.25 KB
 Viewed:  16103 Time(s)

90cf47b.jpg


Back to top
alec(at)alecmyers.com
Guest





PostPosted: Mon Jul 10, 2017 8:26 am    Post subject: IVO Prop current limiter Reply with quote

Ok, so I'm advocating for a design change that's already part of the design. My bad.

On Jul 10, 2017, at 12:11, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com> wrote:
No, only while the command switch is calling
for change of pitch.


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
Dennis Glaeser



Joined: 10 Jan 2006
Posts: 53
Location: Rochester Hills, Michigan

PostPosted: Mon Jul 10, 2017 8:26 am    Post subject: Re: IVO Prop current limiter Reply with quote

kfav8r wrote:
The DPDT switch is mounted in the panel (in my case), along with the red and green LEDs.
For the Arduino setup, I have the relay and the current sensing module in a box behind the panel, and the arduino placed nearby.
On my Arduino layout drawing, the right side is from one of Bob's original drawings. He included the 10 Amp circuit breaker there, since that is what is delivered with the IVOProp.
For wiring, I used 16 AWG for any wires handling prop motor current; that is the size delivered with the prop.
My name is Doug Garland, but true credit goes to Dennis Glaeser for starting this discussion years ago, and, of course, Bob.

All I get credit for is asking the question: what would it take to make the IVO 'dummy proof' to save the gear box Cool The rest is all Bob...

It took me 2 tries to build a working version of Bob's 'original' design. What a blast, working on something designed just for me (at the time)!
Fortunately I didn't have any issues with it working reliably for the couple of years I used it. I moved 'up' to an MT prop, and sold the IVO - hopefully it is still working for the new owner.
What you guys are doing now is a testament to the ingenuity you all have, and the amazing technology available today - at even more amazing prices!!

I remember when I started doing research in prep for building my RV7A (in 2004!!), and discovered the AeroElectric list (and Vans AirForce). Wow!
My plane has been flying for over 9 years now, and I still follow all these forums and continue to expand my education, and stay amazed at all of the talented folks involved who are willing to share their time, effort, and knowledge, with Bob solidly at the head of that line.

Dennis Glaeser


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Mon Jul 10, 2017 9:34 am    Post subject: IVO Prop current limiter Reply with quote

Quote:

I remember when I started doing research in prep for building my RV7A (in 2004!!), and discovered the AeroElectric list (and Vans AirForce). Wow!
My plane has been flying for over 9 years now, and I still follow all these forums and continue to expand my education, and stay amazed at all of the talented folks involved who are willing to share their time, effort, and knowledge, with Bob solidly at the head of that line.

What you're describing is what I call "back of the
napkin germination, evolution and perfection of
an idea". The most elegant solutions are most often
the amalgamation of time and talents in a demonstration
of spontaneous order.

I have had several jobs where this kind of collaboration
and refinement of ideas took place . . . automatically.
The most fun jobs I've had the pleasure to hold.

I think Burt told us during the Mojave roll-out that Voyager
was conceived on the back of a napkin (or perhaps an
envelope) at a local beanery. Now I'm never without my
favorite back of the napkin design tool . . .

http://tinyurl.com/ybum6b78

. . . for decades, some of the most exciting germinations
over tacos at Connie's El Mexico cafe were frustrated
by ball-points that plowed holes in the napkins. Wetting
your finger in salsa is a poor substitute. I discovered
these pens a few years ago. They draw cleanly and damage
free on the cheapest of napkins. I now carry two . . . one to
'talk' with, the other to give away when my partner(s) in
contemplation are impressed with the utility of the tool.

In our case, the 'napkin' is a modern collection of applications
and byte-thrashers, not the least of which is Matt's
servers. But what we do here has roots in antiquity. It
is in the finest traditions offered up by the likes of
Kettering, Edison, Johnson, Beech, Rutan, VanG, et. als.




Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
nuckolls.bob(at)aeroelect
Guest





PostPosted: Mon Jul 10, 2017 7:11 pm    Post subject: IVO Prop current limiter Reply with quote

I proofed the ecb layout I posted. I'll get some
made. I'll have 5 or so boards to 'share' with
anyone who wants to participate in beta-testing
the hardware/software. Boards should be in
about Wednesday.


Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List All times are GMT - 8 Hours
Goto page Previous  1, 2, 3, 4  Next
Page 3 of 4

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group