Today's Message Index:
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1. 07:00 AM - Re: Re: IVO Prop current limiter (Paul A. Fisher)
2. 08:14 AM - Re: Re: IVO Prop current limiter (Alec Myers)
3. 10:45 AM - Re: Re: IVO Prop current limiter (Alec Myers)
Message 1
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Subject: | Re: IVO Prop current limiter |
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.
Paul Fisher
On 7/7/2017 3:03 PM, Robert L. Nuckolls, III wrote:
> At 11:16 AM 7/6/2017, you wrote:
>>
>>
>> > This might be another opportunity for an open source
>> > project. Once you've finely tuned the code, we can
>> > poke it into chips for mounting on a dedicated
>> > ecb . . . have you considered solid-state
>> > switching as opposed to relay?
>>
>>
>> Bob,
>>
>> I'm open to any of your great ideas.
>> I had not considered a solid-state switch instead of a relay,
>> but that does sound like a good way to go.
>>
>> It would be nice to have this in a small package.
>> Right now, I have the Arduino (clone) board in an enclosure,
>> and the other components in the separate enclosure I had
>> been using for your original circuit.
>
> Yup . . . make it work on the bench then
> 'distill' it . . .
>
> Do I recall correctly that once you have
> 'golden code' in the silicon, the chip
> can be lifted out and dropped into an
> embedded controller with minimized
> peripherals?
>
> If I were stuffing this functionality into an
> 8-pin PIC chip, I would explore something
> like this . . .
>
> Emacs!
>
> Set up Q1/R2/Q3 as a classic, ultra-fast current
> limiter. Select R2 to target stall motor current
> limit. Current limit is approximately
>
> I(limit) = Vbe(Q3)/R1
>
> Vbe(Q3) is about 0.6 volts. Hence, setting
> R1 at 0.1 ohms would get you a 6A current
> limit. I think we were shooting for 9A so
> R1 = 0.066 ohms. I would parallel a number
> of resistors on an ECB to achieve 66 milliohms.
>
> Q1 doubles as a motor controller turned OFF
> by clamping gate to ground with Q4.
>
> D8/D9/R10/C11/Z12 conditions the COMMAND SENSE
> signal to a discrete input.
>
> R5/C6 conditions a CURRENT LIMIT SENSE input
> to an analog input.
>
> Q4 is a software driven clamp to remove drive
> from Q1 during a LIMIT CURRENT shut down.
>
> The +12 source in schematic above can be
> BUS, a precision 5v source ie easily acquired for
> small uC chips with a circuit like this:
>
> Emacs!
>
>
> Smartware would read something like this:
>
> Power-up routine SETS a LIMIT LATCH which
> drives gate of Q4 HI.
>
> A rising edge on COMMAND SENSE clears the
> LIMIT LATCH which removes drive from gate of Q4.
>
> LIMIT SENSE is monitored for input greater
> than 0.5 volts for greater than 0.5 second.
> Any excursion below 0.5 volts resets the
> limit timer.
>
> If limit times out, then the LIMIT LATCH
> is SET, gate of Q4 goes HI and motor power
> is removed.
>
> This condition is sustained until next
> rising edge on COMMAND SENSE.
>
> It looks like the tiny Arduino products
> could piggy-back onto a board that hosts
> the peripheral components . . . but as
> long as you're making a board, you might
> explore the option of programming a chip
> in an Arduino development system for
> dropping into your target ECB.
>
> To the extend that any of this is useful, feel
> free to adopt or adapt as you see fit.
>
>
> Bob . . .
>
Message 2
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Subject: | Re: IVO Prop current limiter |
If you're going to use a pic you can dispense can
> On Jul 8, 2017, at 9:59 AM, Paul A. T. 743 Fisher <paulf@hughes.net> wr
ote:
>
> The software that Bob describes would be pretty simple to write for the PI
C12F683 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 har
dware design using a PIC chip instead of the Arduino as an open source proje
ct.
>
> Paul Fisher
>
>> On 7/7/2017 3:03 PM, Robert L. Nuckolls, III wrote:
>> At 11:16 AM 7/6/2017, you wrote:
>>>
>>>
>>> > This might be another opportunity for an open source
>>> > project. Once you've finely tuned the code, we can
>>> > poke it into chips for mounting on a dedicated
>>> > ecb . . . have you considered solid-state
>>> > switching as opposed to relay?
>>>
>>>
>>> Bob,
>>>
>>> I'm open to any of your great ideas.
>>> I had not considered a solid-state switch instead of a relay,
>>> but that does sound like a good way to go.
>>>
>>> It would be nice to have this in a small package.
>>> Right now, I have the Arduino (clone) board in an enclosure,
>>> and the other components in the separate enclosure I had
>>> been using for your original circuit.
>>
>> Yup . . . make it work on the bench then
>> 'distill' it . . .
>>
>> Do I recall correctly that once you have
>> 'golden code' in the silicon, the chip
>> can be lifted out and dropped into an
>> embedded controller with minimized
>> peripherals?
>>
>> If I were stuffing this functionality into an
>> 8-pin PIC chip, I would explore something
>> like this . . .
>>
>> <5a5abb6.jpg>
>>
>> Set up Q1/R2/Q3 as a classic, ultra-fast current
>> limiter. Select R2 to target stall motor current
>> limit. Current limit is approximately
>>
>> I(limit) = Vbe(Q3)/R1
>>
>> Vbe(Q3) is about 0.6 volts. Hence, setting
>> R1 at 0.1 ohms would get you a 6A current
>> limit. I think we were shooting for 9A so
>> R1 = 0.066 ohms. I would parallel a number
>> of resistors on an ECB to achieve 66 milliohms.
>>
>> Q1 doubles as a motor controller turned OFF
>> by clamping gate to ground with Q4.
>>
>> D8/D9/R10/C11/Z12 conditions the COMMAND SENSE
>> signal to a discrete input.
>>
>> R5/C6 conditions a CURRENT LIMIT SENSE input
>> to an analog input.
>>
>> Q4 is a software driven clamp to remove drive
>> from Q1 during a LIMIT CURRENT shut down.
>>
>> The +12 source in schematic above can be
>> BUS, a precision 5v source ie easily acquired for
>> small uC chips with a circuit like this:
>>
>> <5a5ac43.jpg>
>>
>>
>> Smartware would read something like this:
>>
>> Power-up routine SETS a LIMIT LATCH which
>> drives gate of Q4 HI.
>>
>> A rising edge on COMMAND SENSE clears the
>> LIMIT LATCH which removes drive from gate of Q4.
>>
>> LIMIT SENSE is monitored for input greater
>> than 0.5 volts for greater than 0.5 second.
>> Any excursion below 0.5 volts resets the
>> limit timer.
>>
>> If limit times out, then the LIMIT LATCH
>> is SET, gate of Q4 goes HI and motor power
>> is removed.
>>
>> This condition is sustained until next
>> rising edge on COMMAND SENSE.
>>
>> It looks like the tiny Arduino products
>> could piggy-back onto a board that hosts
>> the peripheral components . . . but as
>> long as you're making a board, you might
>> explore the option of programming a chip
>> in an Arduino development system for
>> dropping into your target ECB.
>>
>> To the extend that any of this is useful, feel
>> free to adopt or adapt as you see fit.
>>
>>
>>
>>
>> Bob . . .
>>
>
Message 3
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Subject: | Re: IVO Prop current limiter |
Sorry - defective iPhones and all that.
Possible simplifications to consider:
- If you=99re 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.
- dispense with the command sense input, and power the PIC with a simple
potential divider from the command sense network instead. To reset the
timer, remove the power shutting down the PIC and rebooting it when
power is restored.
> On Jul 8, 2017, at 11:12 AM, Alec Myers <alec@alecmyers.com> wrote:
>
>
> If you're going to use a pic you can dispense can
> On Jul 8, 2017, at 9:59 AM, Paul A. T. 743 Fisher <paulf@hughes.net
<mailto:paulf@hughes.net>> wrote:
>
>> 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.
>>
>> Paul Fisher
>>
>> On 7/7/2017 3:03 PM, Robert L. Nuckolls, III wrote:
>>> At 11:16 AM 7/6/2017, you wrote:
<kfav8r@outlook.com> <mailto:kfav8r@outlook.com>
>>>>
>>>>
>>>> > This might be another opportunity for an open source
>>>> > project. Once you've finely tuned the code, we can
>>>> > poke it into chips for mounting on a dedicated
>>>> > ecb . . . have you considered solid-state
>>>> > switching as opposed to relay?
>>>>
>>>>
>>>> Bob,
>>>>
>>>> I'm open to any of your great ideas.
>>>> I had not considered a solid-state switch instead of a relay,
>>>> but that does sound like a good way to go.
>>>>
>>>> It would be nice to have this in a small package.
>>>> Right now, I have the Arduino (clone) board in an enclosure,
>>>> and the other components in the separate enclosure I had
>>>> been using for your original circuit.
>>>
>>> Yup . . . make it work on the bench then
>>> 'distill' it . . .
>>>
>>> Do I recall correctly that once you have
>>> 'golden code' in the silicon, the chip
>>> can be lifted out and dropped into an
>>> embedded controller with minimized
>>> peripherals?
>>>
>>> If I were stuffing this functionality into an
>>> 8-pin PIC chip, I would explore something
>>> like this . . .
>>>
>>> <5a5abb6.jpg>
>>>
>>> Set up Q1/R2/Q3 as a classic, ultra-fast current
>>> limiter. Select R2 to target stall motor current
>>> limit. Current limit is approximately
>>>
>>> I(limit) = Vbe(Q3)/R1
>>>
>>> Vbe(Q3) is about 0.6 volts. Hence, setting
>>> R1 at 0.1 ohms would get you a 6A current
>>> limit. I think we were shooting for 9A so
>>> R1 = 0.066 ohms. I would parallel a number
>>> of resistors on an ECB to achieve 66 milliohms.
>>>
>>> Q1 doubles as a motor controller turned OFF
>>> by clamping gate to ground with Q4.
>>>
>>> D8/D9/R10/C11/Z12 conditions the COMMAND SENSE
>>> signal to a discrete input.
>>>
>>> R5/C6 conditions a CURRENT LIMIT SENSE input
>>> to an analog input.
>>>
>>> Q4 is a software driven clamp to remove drive
>>> from Q1 during a LIMIT CURRENT shut down.
>>>
>>> The +12 source in schematic above can be
>>> BUS, a precision 5v source ie easily acquired for
>>> small uC chips with a circuit like this:
>>>
>>> <5a5ac43.jpg>
>>>
>>>
>>> Smartware would read something like this:
>>>
>>> Power-up routine SETS a LIMIT LATCH which
>>> drives gate of Q4 HI.
>>>
>>> A rising edge on COMMAND SENSE clears the
>>> LIMIT LATCH which removes drive from gate of Q4.
>>>
>>> LIMIT SENSE is monitored for input greater
>>> than 0.5 volts for greater than 0.5 second.
>>> Any excursion below 0.5 volts resets the
>>> limit timer.
>>>
>>> If limit times out, then the LIMIT LATCH
>>> is SET, gate of Q4 goes HI and motor power
>>> is removed.
>>>
>>> This condition is sustained until next
>>> rising edge on COMMAND SENSE.
>>>
>>> It looks like the tiny Arduino products
>>> could piggy-back onto a board that hosts
>>> the peripheral components . . . but as
>>> long as you're making a board, you might
>>> explore the option of programming a chip
>>> in an Arduino development system for
>>> dropping into your target ECB.
>>>
>>> To the extend that any of this is useful, feel
>>> free to adopt or adapt as you see fit.
>>>
>>>
>>>
>>>
>>> Bob . . .
>>>
>>
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