PSC data sheet
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Posts: 46,084
My PSC's arrived and the data sheet answers most of my earlier questions
about the command sequence. My initial CPU board won't be up and ready
to drive it for about another week, so I won't be able to fully test it
until then.
However, unless I've missed something , I don't think the data sheet
mentions where the servos are positioned by default immediately after
power up, if there has not yet been a command sent.
What is the default servo pulse widths sent, if any, from the PSC
outputs, following a power up? Obviously I'd like to ensure the robot
(soft) shuts down in the same position as it will try to later start up.
Andy
about the command sequence. My initial CPU board won't be up and ready
to drive it for about another week, so I won't be able to fully test it
until then.
However, unless I've missed something , I don't think the data sheet
mentions where the servos are positioned by default immediately after
power up, if there has not yet been a command sent.
What is the default servo pulse widths sent, if any, from the PSC
outputs, following a power up? Obviously I'd like to ensure the robot
(soft) shuts down in the same position as it will try to later start up.
Andy
Comments
Did you receive an answer on this question? I haven't seen a
reply yet and I'm curious too.
Thanks,
Tim
At 10:24 AM 4/24/2004, you wrote:
>My PSC's arrived and the data sheet answers most of my earlier questions
>about the command sequence. My initial CPU board won't be up and ready
>to drive it for about another week, so I won't be able to fully test it
>until then.
>
>However, unless I've missed something , I don't think the data sheet
>mentions where the servos are positioned by default immediately after
>power up, if there has not yet been a command sent.
>
>What is the default servo pulse widths sent, if any, from the PSC
>outputs, following a power up? Obviously I'd like to ensure the robot
>(soft) shuts down in the same position as it will try to later start up.
>
>Andy
>
>
>
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Not yet. If I get some free time this week, I may power up the card on
its own and look with a scope. If this chip is now going into the new
Hexcrawler, then there is probably a lot of final production checking
out that's keeping everyone on that project very busy.
Having thought a little more about my question, I realize now it does
have implications if a robot gets stuck in an awkward position (eg leg
trapped in a hole or an arm holding a fragile object) where repowering
it up may cause a servo to try and revert fast to a position that can
cause damage to the robot itself or something else. However, I suspect
this is probably going to be just a fact of life for low cost robotics,
as I don't think there is much that can be done about that without
having a pre-readable position detection system on every servo output.
Andy
>>>Hi Andy,
Did you receive an answer on this question? I haven't seen a
reply yet and I'm curious too.
Thanks,
Tim
At 10:24 AM 4/24/2004, you wrote:
>My PSC's arrived and the data sheet answers most of my earlier
questions
>about the command sequence. My initial CPU board won't be up and ready
>to drive it for about another week, so I won't be able to fully test it
>until then.
>
>However, unless I've missed something , I don't think the data sheet
>mentions where the servos are positioned by default immediately after
>power up, if there has not yet been a command sent.
>
>What is the default servo pulse widths sent, if any, from the PSC
>outputs, following a power up? Obviously I'd like to ensure the robot
>(soft) shuts down in the same position as it will try to later start
up.
>
>Andy
channel is set to 1.5 ms (center) and ramping is disabled.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: Timothy Medema [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=owbWMhfb7IqMzyeIhWfpenKpSLH3UM8t7KkN4A-r8VIsiGyeWRQlKCXkxfnNEINFkDAgSamkpB8adUGOpA]timm@c...[/url
Sent: Monday, April 26, 2004 10:28 AM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] PSC data sheet
Hi Andy,
Did you receive an answer on this question? I haven't seen a
reply yet and I'm curious too.
Thanks,
Tim
At 10:24 AM 4/24/2004, you wrote:
>My PSC's arrived and the data sheet answers most of my earlier
>questions about the command sequence. My initial CPU board won't be up
>and ready to drive it for about another week, so I won't be able to
>fully test it until then.
>
>However, unless I've missed something , I don't think the data sheet
>mentions where the servos are positioned by default immediately after
>power up, if there has not yet been a command sent.
>
>What is the default servo pulse widths sent, if any, from the PSC
>outputs, following a power up? Obviously I'd like to ensure the robot
>(soft) shuts down in the same position as it will try to later start
>up.
>
>Andy
Tim
At 09:31 AM 4/26/2004, you wrote:
>I checked with the PSC engineer: When the PSC is powered up, each
>channel is set to 1.5 ms (center) and ramping is disabled.
>
>-- Jon Williams
>-- Applications Engineer, Parallax
>-- Dallas Office
>
>
>
Original Message
>From: Timothy Medema [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=bY5mZZKGPNbIukr04owIQ-ok8-nvTMSMWez--bt5UKq40MFXevZxgCGf3zuQs26MKe8-ADV1jd5ls6rZAu0]timm@c...[/url
>Sent: Monday, April 26, 2004 10:28 AM
>To: basicstamps@yahoogroups.com
>Subject: Re: [noparse][[/noparse]basicstamps] PSC data sheet
>
>
>
>Hi Andy,
>
> Did you receive an answer on this question? I haven't seen a
>reply yet and I'm curious too.
>
>Thanks,
>
>Tim
>
>
>At 10:24 AM 4/24/2004, you wrote:
> >My PSC's arrived and the data sheet answers most of my earlier
> >questions about the command sequence. My initial CPU board won't be up
>
> >and ready to drive it for about another week, so I won't be able to
> >fully test it until then.
> >
> >However, unless I've missed something , I don't think the data sheet
> >mentions where the servos are positioned by default immediately after
> >power up, if there has not yet been a command sent.
> >
> >What is the default servo pulse widths sent, if any, from the PSC
> >outputs, following a power up? Obviously I'd like to ensure the robot
> >(soft) shuts down in the same position as it will try to later start
> >up.
> >
> >Andy
>
>
>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.
>
>Yahoo! Groups Links
>
>
>
>
May I proffer a future PSC design "improvement" suggestion? If the PSC's
servo position memory is non-volatile, would it not be a good idea to
have an additional or modified read command which would allow read back
of the last set position of each servo, regardless of whether the PSC
was powered down in the interim? Then on the next power up, the user
could have the option of reading and knowing the current servo positions
first, and then the choice of letting them stay, or setting them to move
from there at a safe speed, rather than having them always "reset" and
move at full power and speed to the center default. The separate servo
power line could always be held off a short time to allow for the
housekeeping to happen first.
Andy
yes, it's a good idea.
-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office
Original Message
From: Andy Reichert [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ij_xwZ3WMh59gEoQ7wi1qR6TP_7YI0VjTaJ512uwSAOxYt1_ZuSxd7Xn31pABEirN_O4AGPXX7A_EUV0UQ]andy_r@i...[/url
Sent: Monday, April 26, 2004 12:54 PM
To: basicstamps@yahoogroups.com
Subject: Re: [noparse][[/noparse]basicstamps] PSC data sheet
Thanks Jon,
May I proffer a future PSC design "improvement" suggestion? If the PSC's
servo position memory is non-volatile, would it not be a good idea to
have an additional or modified read command which would allow read back
of the last set position of each servo, regardless of whether the PSC
was powered down in the interim? Then on the next power up, the user
could have the option of reading and knowing the current servo positions
first, and then the choice of letting them stay, or setting them to move
from there at a safe speed, rather than having them always "reset" and
move at full power and speed to the center default. The separate servo
power line could always be held off a short time to allow for the
housekeeping to happen first.
Andy