R/C pulse processing?
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Posts: 46,084
Hi,
I've mostly been a lurker on this list but am venturing out of the
woodwork with a question for y'all:
Is a Stamp fast enough to measure the output of a four-channel R/C
model airplane receiver, perform a little bit of math on one of the
pulse widths, and regenerate the entire pulse frame, reliably and
accurately? In other words I want to insert a Stamp in between an FM
receiver chip's output and an existing servo processing circuit. The
only signal I can get at is the pulse stream right out of the
receiver, which has all four servo pulses sent one after the other on
one wire. It's the standard 1-2 msec pulse width modulated format,
with the start of a frame signalled by a low level much longer than 2
msec, and frames repeating about every 50 msec. I need to regenerate
a similar pulse stream rather than drive individual servos
separately, which I've done before. I'm guessing I might need to use
an assembly coded PIC for this, or some external hardware to keep the
timing accurate enough.
If anyone has tried something like this, I would love to hear about
how well it worked!
thanks,
Alex Stahl
Pixar Animation Studios
alex@p...
I've mostly been a lurker on this list but am venturing out of the
woodwork with a question for y'all:
Is a Stamp fast enough to measure the output of a four-channel R/C
model airplane receiver, perform a little bit of math on one of the
pulse widths, and regenerate the entire pulse frame, reliably and
accurately? In other words I want to insert a Stamp in between an FM
receiver chip's output and an existing servo processing circuit. The
only signal I can get at is the pulse stream right out of the
receiver, which has all four servo pulses sent one after the other on
one wire. It's the standard 1-2 msec pulse width modulated format,
with the start of a frame signalled by a low level much longer than 2
msec, and frames repeating about every 50 msec. I need to regenerate
a similar pulse stream rather than drive individual servos
separately, which I've done before. I'm guessing I might need to use
an assembly coded PIC for this, or some external hardware to keep the
timing accurate enough.
If anyone has tried something like this, I would love to hear about
how well it worked!
thanks,
Alex Stahl
Pixar Animation Studios
alex@p...
Comments
can monitor via PulseIN on each channel, but 4 at the same time might be pushing
it.
Nuts and Volts had an article on RC Failsafes that might interest you. He used
a PIC....
http://tinyurl.com/jbd7
And you work for Pixar!! How cool is that! What is the crew like? I'd imagine
the group as being spunky based on the fun stuff you guys put out!
Hope that helps,
Tim
>>> alex@p... 08/07/03 11:45AM >>>
Hi,
I've mostly been a lurker on this list but am venturing out of the
woodwork with a question for y'all:
Is a Stamp fast enough to measure the output of a four-channel R/C
model airplane receiver, perform a little bit of math on one of the
pulse widths, and regenerate the entire pulse frame, reliably and
accurately? In other words I want to insert a Stamp in between an FM
receiver chip's output and an existing servo processing circuit. The
only signal I can get at is the pulse stream right out of the
receiver, which has all four servo pulses sent one after the other on
one wire. It's the standard 1-2 msec pulse width modulated format,
with the start of a frame signalled by a low level much longer than 2
msec, and frames repeating about every 50 msec. I need to regenerate
a similar pulse stream rather than drive individual servos
separately, which I've done before. I'm guessing I might need to use
an assembly coded PIC for this, or some external hardware to keep the
timing accurate enough.
If anyone has tried something like this, I would love to hear about
how well it worked!
thanks,
Alex Stahl
Pixar Animation Studios
alex@p...
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at 3AM trying to reboot all 2000 rendering processors :-)
>I don't think the stamp can monitor all 4 channels at the same time.
>I know you can monitor via PulseIN on each channel, but 4 at the
>same time might be pushing it.
>
>Nuts and Volts had an article on RC Failsafes that might interest
>you. He used a PIC....
>http://tinyurl.com/jbd7
>
>And you work for Pixar!! How cool is that! What is the crew like?
>I'd imagine the group as being spunky based on the fun stuff you
>guys put out!
>
>Hope that helps,
>Tim
>
>>>> alex@p... 08/07/03 11:45AM >>>
>Hi,
>
>I've mostly been a lurker on this list but am venturing out of the
>woodwork with a question for y'all:
>
>Is a Stamp fast enough to measure the output of a four-channel R/C
>model airplane receiver, perform a little bit of math on one of the
>pulse widths, and regenerate the entire pulse frame, reliably and
>accurately? In other words I want to insert a Stamp in between an FM
>receiver chip's output and an existing servo processing circuit. The
>only signal I can get at is the pulse stream right out of the
>receiver, which has all four servo pulses sent one after the other on
>one wire. It's the standard 1-2 msec pulse width modulated format,
>with the start of a frame signalled by a low level much longer than 2
>msec, and frames repeating about every 50 msec. I need to regenerate
>a similar pulse stream rather than drive individual servos
>separately, which I've done before. I'm guessing I might need to use
>an assembly coded PIC for this, or some external hardware to keep the
>timing accurate enough.
>
>If anyone has tried something like this, I would love to hear about
>how well it worked!
>
>thanks,
>
>Alex Stahl
>Pixar Animation Studios
>alex@p...
>
>To UNSUBSCRIBE, just send mail to:
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>
>
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>
>
>
>
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>
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If the time between pulses is also at least a couple of millisecond
and not a critical parameter in the data stream you have to send,
then it should be possible with the Stamp. There is enough time to
capture each pulse with 5 successive PULSIN commands, and do the
math, and resend the stream, and be ready and waiting to receive the
next frame. You can do a lot in 50 milliseconds.
-- best regards
Tracy Allen
electronically monitored ecosystems
http://www.emesystems.com
mailto:tracy@e...
>Hi,
>
>I've mostly been a lurker on this list but am venturing out of the
>woodwork with a question for y'all:
>
>Is a Stamp fast enough to measure the output of a four-channel R/C
>model airplane receiver, perform a little bit of math on one of the
>pulse widths, and regenerate the entire pulse frame, reliably and
>accurately? In other words I want to insert a Stamp in between an FM
>receiver chip's output and an existing servo processing circuit. The
>only signal I can get at is the pulse stream right out of the
>receiver, which has all four servo pulses sent one after the other on
>one wire. It's the standard 1-2 msec pulse width modulated format,
>with the start of a frame signalled by a low level much longer than 2
>msec, and frames repeating about every 50 msec. I need to regenerate
>a similar pulse stream rather than drive individual servos
>separately, which I've done before. I'm guessing I might need to use
>an assembly coded PIC for this, or some external hardware to keep the
>timing accurate enough.
>
>If anyone has tried something like this, I would love to hear about
>how well it worked!
>
>thanks,
>
>Alex Stahl
>Pixar Animation Studios
>alex@p...
>
critical (doesn't need to be measured or preserved). Do you think
that's too fast for successive PULSIN's to capture? I'll find out
soon enough :-)
Also the frames repeat at 50 Hz, not every 50msec, that was a brain
fart on my part. Still, there's about 13 msec 'dead air' between
frames and the math is minimal, so I guess I'll give it a try with a
2sx Stamp.
thanks for all the replies so far,
Alex S.
>Within each frame, how long is the time between each 1-2 ms pulse?
>If the time between pulses is also at least a couple of millisecond
>and not a critical parameter in the data stream you have to send,
>then it should be possible with the Stamp. There is enough time to
>capture each pulse with 5 successive PULSIN commands, and do the
>math, and resend the stream, and be ready and waiting to receive the
>next frame. You can do a lot in 50 milliseconds.
>
> -- best regards
> Tracy Allen
> electronically monitored ecosystems
> http://www.emesystems.com
> mailto:tracy@e...
>
>
>>Hi,
>>
>>I've mostly been a lurker on this list but am venturing out of the
>>woodwork with a question for y'all:
>>
>>Is a Stamp fast enough to measure the output of a four-channel R/C
>>model airplane receiver, perform a little bit of math on one of the
>>pulse widths, and regenerate the entire pulse frame, reliably and
>>accurately? In other words I want to insert a Stamp in between an FM
>>receiver chip's output and an existing servo processing circuit. The
>>only signal I can get at is the pulse stream right out of the
>>receiver, which has all four servo pulses sent one after the other on
>>one wire. It's the standard 1-2 msec pulse width modulated format,
>>with the start of a frame signalled by a low level much longer than 2
>>msec, and frames repeating about every 50 msec. I need to regenerate
>>a similar pulse stream rather than drive individual servos
>>separately, which I've done before. I'm guessing I might need to use
>>an assembly coded PIC for this, or some external hardware to keep the
>>timing accurate enough.
>>
>>If anyone has tried something like this, I would love to hear about
>>how well it worked!
>>
>>thanks,
>>
>>Alex Stahl
>>Pixar Animation Studios
>>alex@p...
>>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the
>Subject and Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
only be about 100 microseconds on the '2sx. So one full millisecond
between pulses should be plenty. 50 hz, 20 milliseconds per frame.
There should be time in there to squeeze in the calculation. But it
is going to take some time to transmit it all, too, and maybe you
can't miss the start of the next frame.
-- Tracy
>The time between each pulse is barely one millisecond, but it isn't
>critical (doesn't need to be measured or preserved). Do you think
>that's too fast for successive PULSIN's to capture? I'll find out
>soon enough :-)
>
>Also the frames repeat at 50 Hz, not every 50msec, that was a brain
>fart on my part. Still, there's about 13 msec 'dead air' between
>frames and the math is minimal, so I guess I'll give it a try with a
>2sx Stamp.
>
>thanks for all the replies so far,
>
>Alex S.
>
>
>
>>Within each frame, how long is the time between each 1-2 ms pulse?
>>If the time between pulses is also at least a couple of millisecond
>>and not a critical parameter in the data stream you have to send,
>>then it should be possible with the Stamp. There is enough time to
>>capture each pulse with 5 successive PULSIN commands, and do the
>>math, and resend the stream, and be ready and waiting to receive the
>>next frame. You can do a lot in 50 milliseconds.
>>
>> -- best regards
>> Tracy Allen
>> electronically monitored ecosystems
>> http://www.emesystems.com
>> mailto:tracy@e...
>>
>>
>>>Hi,
>>>
>>>I've mostly been a lurker on this list but am venturing out of the
>>>woodwork with a question for y'all:
>>>
>>>Is a Stamp fast enough to measure the output of a four-channel R/C
>>>model airplane receiver, perform a little bit of math on one of the
>>>pulse widths, and regenerate the entire pulse frame, reliably and
>>>accurately? In other words I want to insert a Stamp in between an FM
>>>receiver chip's output and an existing servo processing circuit. The
>>>only signal I can get at is the pulse stream right out of the
>>>receiver, which has all four servo pulses sent one after the other on
>>>one wire. It's the standard 1-2 msec pulse width modulated format,
>>>with the start of a frame signalled by a low level much longer than 2
>>>msec, and frames repeating about every 50 msec. I need to regenerate
>>>a similar pulse stream rather than drive individual servos
>>>separately, which I've done before. I'm guessing I might need to use
>>>an assembly coded PIC for this, or some external hardware to keep the
>>>timing accurate enough.
>>>
>>>If anyone has tried something like this, I would love to hear about
>>>how well it worked!
>>>
>>>thanks,
>>>
>>>Alex Stahl
>>>Pixar Animation Studios
>>>alex@p...
>>>
>>
>>To UNSUBSCRIBE, just send mail to:
>> basicstamps-unsubscribe@yahoogroups.com
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>>Subject and Body of the message will be ignored.
>>
>>
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>
>
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>only be about 100 microseconds on the '2sx. So one full millisecond
>between pulses should be plenty. 50 hz, 20 milliseconds per frame.
>There should be time in there to squeeze in the calculation. But it
>is going to take some time to transmit it all, too, and maybe you
>can't miss the start of the next frame.
Yeah, that's what I'm afraid of. Although come to think of it, I
probably can afford to miss every other frame, as long as I can
detect the long low pulse in between frames and never get mixed up on
where frame start is.
thanks,
Alex
>
> -- Tracy
>
>
>
>
>>The time between each pulse is barely one millisecond, but it isn't
>>critical (doesn't need to be measured or preserved). Do you think
>>that's too fast for successive PULSIN's to capture? I'll find out
>>soon enough :-)
>>
>>Also the frames repeat at 50 Hz, not every 50msec, that was a brain
>>fart on my part. Still, there's about 13 msec 'dead air' between
>>frames and the math is minimal, so I guess I'll give it a try with a
>>2sx Stamp.
>>
>>thanks for all the replies so far,
>>
>>Alex S.
>>
>>
>>
>>>Within each frame, how long is the time between each 1-2 ms pulse?
>>>If the time between pulses is also at least a couple of millisecond
>>>and not a critical parameter in the data stream you have to send,
>>>then it should be possible with the Stamp. There is enough time to
>>>capture each pulse with 5 successive PULSIN commands, and do the
>>>math, and resend the stream, and be ready and waiting to receive the
>>>next frame. You can do a lot in 50 milliseconds.
>>>
>>> -- best regards
>>> Tracy Allen
>>> electronically monitored ecosystems
>>> http://www.emesystems.com
>>> mailto:tracy@e...
>>>
>>>
>>>>Hi,
>>>>
>>>>I've mostly been a lurker on this list but am venturing out of the
>>>>woodwork with a question for y'all:
>>>>
>>>>Is a Stamp fast enough to measure the output of a four-channel R/C
>>>>model airplane receiver, perform a little bit of math on one of the
>>>>pulse widths, and regenerate the entire pulse frame, reliably and
>>>>accurately? In other words I want to insert a Stamp in between an FM
>>>>receiver chip's output and an existing servo processing circuit. The
>>>>only signal I can get at is the pulse stream right out of the
>>>>receiver, which has all four servo pulses sent one after the other on
>>>>one wire. It's the standard 1-2 msec pulse width modulated format,
>>>>with the start of a frame signalled by a low level much longer than 2
>>>>msec, and frames repeating about every 50 msec. I need to regenerate
>>>>a similar pulse stream rather than drive individual servos
>>>>separately, which I've done before. I'm guessing I might need to use
>>>>an assembly coded PIC for this, or some external hardware to keep the
>>>>timing accurate enough.
>>>>
>>>>If anyone has tried something like this, I would love to hear about
>>>>how well it worked!
>>>>
>>>>thanks,
>>>>
>>>>Alex Stahl
>>>>Pixar Animation Studios
>>>>alex@p...
>>>>
>>>
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>>>from the same email address that you subscribed. Text in the
>>>Subject and Body of the message will be ignored.
>>>
>>>
>>>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>>
>>
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>>Subject and Body of the message will be ignored.
>>
>>
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>
>
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>Subject and Body of the message will be ignored.
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