Board of Education & Servo not working
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Posts: 46,084
Help!
I'm a newbie, just wired up my first servo experiment, (which is
why I got into this stuff in the first place).
I attached a Hitec HS-700BB servo to the Board Of Education's
servo connection #12. That seemed to work fine.
Then I attached a second servo (a Hitec HS-300) to
the servo connection #14).
For a minute, the original servo worked, but the second one did
nothing. I may have had the servo connection plug upside down
on the second one, not sure, I disconnected it promptly and tried
moving the original servo (700BB) over to jack #14.
It didn't work. Now, no matter what jack I plug either into, they
just sit there and chatter. Did I burn something up or
something?
Here's my code, (as copied from the "What's A Microcontroller"
document:
x var word
output 12
here:
for x = 1 to 100
pulsout 12,500
pause 10
next
pause 500
for x = 1 to 100
pulsout 12,1000
pause 10
next
pause 500
goto here
Oddly enough, if I insert the line:
high 12
before the first pulsout line, and then
low 12
before the second pulsout line,
the HS300 will operate, moving from one extreme to the other,
(regardless of how wide I set the pulse, always goes to the
extremes).
The HS700BB refuses to do anything but chatter regardless
now.
Please help. Did I screw something up? I tried hitting the reset
button on the BOE a ton of times, restarted my PC, plugged and
unplugged the BOE a zillion times, nothing works.
Help!
I read in Scott Edwards' book "Programming and customing the
basic stamp computer" that you're not supposed to hook servos
up directly to the stamp, you're supposed to use a separate
battery. But I'm using the BOE, and the documentation seems to
encourage you to go ahead and hook the servo up to the BOE
directly. Did I over-do it with two servo's? Though my code really
only controlled one servo at a time.
Thanks,
Mike
I'm a newbie, just wired up my first servo experiment, (which is
why I got into this stuff in the first place).
I attached a Hitec HS-700BB servo to the Board Of Education's
servo connection #12. That seemed to work fine.
Then I attached a second servo (a Hitec HS-300) to
the servo connection #14).
For a minute, the original servo worked, but the second one did
nothing. I may have had the servo connection plug upside down
on the second one, not sure, I disconnected it promptly and tried
moving the original servo (700BB) over to jack #14.
It didn't work. Now, no matter what jack I plug either into, they
just sit there and chatter. Did I burn something up or
something?
Here's my code, (as copied from the "What's A Microcontroller"
document:
x var word
output 12
here:
for x = 1 to 100
pulsout 12,500
pause 10
next
pause 500
for x = 1 to 100
pulsout 12,1000
pause 10
next
pause 500
goto here
Oddly enough, if I insert the line:
high 12
before the first pulsout line, and then
low 12
before the second pulsout line,
the HS300 will operate, moving from one extreme to the other,
(regardless of how wide I set the pulse, always goes to the
extremes).
The HS700BB refuses to do anything but chatter regardless
now.
Please help. Did I screw something up? I tried hitting the reset
button on the BOE a ton of times, restarted my PC, plugged and
unplugged the BOE a zillion times, nothing works.
Help!
I read in Scott Edwards' book "Programming and customing the
basic stamp computer" that you're not supposed to hook servos
up directly to the stamp, you're supposed to use a separate
battery. But I'm using the BOE, and the documentation seems to
encourage you to go ahead and hook the servo up to the BOE
directly. Did I over-do it with two servo's? Though my code really
only controlled one servo at a time.
Thanks,
Mike
Comments
Al Williams
AWC
* NEW: Floating point A/D: http://www.al-williams.com/awce/pak9.htm
>
Original Message
> From: fathalloran@y... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ZKBtMP_R_1avCv_NTQboZFgZ1zPzW7NQFRUcJ5HTRd0DA0FBSsvDxVLV1PeGpoceRlSzSCXcYn2x_f--sfnhKg]fathalloran@y...[/url
> Sent: Wednesday, April 18, 2001 3:01 AM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] Board of Education & Servo not working
>
>
> Help!
>
> I'm a newbie, just wired up my first servo experiment, (which is
> why I got into this stuff in the first place).
>
> I attached a Hitec HS-700BB servo to the Board Of Education's
> servo connection #12. That seemed to work fine.
>
> Then I attached a second servo (a Hitec HS-300) to
> the servo connection #14).
>
> For a minute, the original servo worked, but the second one did
> nothing. I may have had the servo connection plug upside down
> on the second one, not sure, I disconnected it promptly and tried
> moving the original servo (700BB) over to jack #14.
>
> It didn't work. Now, no matter what jack I plug either into, they
> just sit there and chatter. Did I burn something up or
> something?
>
> Here's my code, (as copied from the "What's A Microcontroller"
> document:
>
> x var word
> output 12
> here:
> for x = 1 to 100
> pulsout 12,500
> pause 10
> next
> pause 500
> for x = 1 to 100
> pulsout 12,1000
> pause 10
> next
> pause 500
> goto here
>
> Oddly enough, if I insert the line:
>
> high 12
>
> before the first pulsout line, and then
>
> low 12
>
> before the second pulsout line,
> the HS300 will operate, moving from one extreme to the other,
> (regardless of how wide I set the pulse, always goes to the
> extremes).
>
> The HS700BB refuses to do anything but chatter regardless
> now.
>
> Please help. Did I screw something up? I tried hitting the reset
> button on the BOE a ton of times, restarted my PC, plugged and
> unplugged the BOE a zillion times, nothing works.
>
> Help!
>
> I read in Scott Edwards' book "Programming and customing the
> basic stamp computer" that you're not supposed to hook servos
> up directly to the stamp, you're supposed to use a separate
> battery. But I'm using the BOE, and the documentation seems to
> encourage you to go ahead and hook the servo up to the BOE
> directly. Did I over-do it with two servo's? Though my code really
> only controlled one servo at a time.
>
> Thanks,
>
> Mike
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
> why I got into this stuff in the first place).
Is there a capacitor inline with the servo? A servo will draw enough
current to pull the voltage low. When the voltage drops below four point
something volts, the BS2 will undergo a brownout. At that point the BS2
stops sending instructions to the servo. Now the servo stops moving and the
voltage comes back up. At that point the BS2 restarts itself and begins
executing the first line of instruction. The process will repeat itself
over and over again.
When my student's servos behave erratically, it is almost always a missing
or incorrectly installed cap. Use a 3300 uF cap.
The cap acts as a temporary battery for the servo.
Paul
everything shoudl be pre-wired. However, in scanning the Hitec site, I saw
that you can get their servos for use with different RC units, which have
different connector pin-outs. If the servo has a three-pin connector with
the positive power connection in the middle, you probably did not fry
anything hooking it up backwards.
As for the power, the BOE has a built-in 5-volt, 1 amp regulator to power
everything -- the same setup works fine on my robot.
What you need to do is insult the servo instructions and find out what the
pulse width is for the neutral (center) position. After you get this, look
in your Stamp manual (you have one, right?) and find out what the pulse
width is for each "count" on the PULSOUT command. Divide this into the pulse
width specified for the neutral position on the servo -- this should give
you an approximate value for the PULSOUT command.
Original Message
> Do you have the servo ground connected to the logic ground?
> >
Original Message
> > I attached a Hitec HS-700BB servo to the Board Of Education's
> > servo connection #12. That seemed to work fine.
> >
> > Then I attached a second servo (a Hitec HS-300) to
> > the servo connection #14).
> >
> > For a minute, the original servo worked, but the second one did
> > nothing. I may have had the servo connection plug upside down
> > on the second one, not sure, I disconnected it promptly and tried
> > moving the original servo (700BB) over to jack #14.
> >
> > It didn't work. Now, no matter what jack I plug either into, they
> > just sit there and chatter. Did I burn something up or
> > something?
> >
> > Here's my code, (as copied from the "What's A Microcontroller"
> > document:
> >
> > x var word
> > output 12
> > here:
> > for x = 1 to 100
> > pulsout 12,500
> > pause 10
> > next
> > pause 500
> > for x = 1 to 100
> > pulsout 12,1000
> > pause 10
> > next
> > pause 500
> > goto here
> >
> > Oddly enough, if I insert the line:
> >
> > high 12
> >
> > before the first pulsout line, and then
> >
> > low 12
> >
> > before the second pulsout line,
> > the HS300 will operate, moving from one extreme to the other,
> > (regardless of how wide I set the pulse, always goes to the
> > extremes).
> >
> > The HS700BB refuses to do anything but chatter regardless
> > now.
> >
> > Please help. Did I screw something up? I tried hitting the reset
> > button on the BOE a ton of times, restarted my PC, plugged and
> > unplugged the BOE a zillion times, nothing works.
> >
> > Help!
> >
> > I read in Scott Edwards' book "Programming and customing the
> > basic stamp computer" that you're not supposed to hook servos
> > up directly to the stamp, you're supposed to use a separate
> > battery. But I'm using the BOE, and the documentation seems to
> > encourage you to go ahead and hook the servo up to the BOE
> > directly. Did I over-do it with two servo's? Though my code really
> > only controlled one servo at a time.
you are using is for continous rotation, and I guess you know that, but I'm
just wondering if both servos had the modification.
I have a BOE and power 3 servos using the on-board connections. What power
supply are you using? If you are using the 9 volt battery and it's fresh, then
you can rule out the battery power brownouts. Same goes, if you are using the
wall wart, which supplies about 12 volts or more.
In the boe docs, they talk about 2 different versions of the BOE. If you have
the later revision, they you shouldn't need any additional hardware to control
your servos. I've been having 6 months of success with my BOE.
Hope this helps a little.
dave
--- fathalloran@y... wrote:
> Help!
>
> I'm a newbie, just wired up my first servo experiment, (which is
> why I got into this stuff in the first place).
>
> I attached a Hitec HS-700BB servo to the Board Of Education's
> servo connection #12. That seemed to work fine.
>
> Then I attached a second servo (a Hitec HS-300) to
> the servo connection #14).
>
> For a minute, the original servo worked, but the second one did
> nothing. I may have had the servo connection plug upside down
> on the second one, not sure, I disconnected it promptly and tried
> moving the original servo (700BB) over to jack #14.
>
> It didn't work. Now, no matter what jack I plug either into, they
> just sit there and chatter. Did I burn something up or
> something?
>
> Here's my code, (as copied from the "What's A Microcontroller"
> document:
>
> x var word
> output 12
> here:
> for x = 1 to 100
> pulsout 12,500
> pause 10
> next
> pause 500
> for x = 1 to 100
> pulsout 12,1000
> pause 10
> next
> pause 500
> goto here
>
> Oddly enough, if I insert the line:
>
> high 12
>
> before the first pulsout line, and then
>
> low 12
>
> before the second pulsout line,
> the HS300 will operate, moving from one extreme to the other,
> (regardless of how wide I set the pulse, always goes to the
> extremes).
>
> The HS700BB refuses to do anything but chatter regardless
> now.
>
> Please help. Did I screw something up? I tried hitting the reset
> button on the BOE a ton of times, restarted my PC, plugged and
> unplugged the BOE a zillion times, nothing works.
>
> Help!
>
> I read in Scott Edwards' book "Programming and customing the
> basic stamp computer" that you're not supposed to hook servos
> up directly to the stamp, you're supposed to use a separate
> battery. But I'm using the BOE, and the documentation seems to
> encourage you to go ahead and hook the servo up to the BOE
> directly. Did I over-do it with two servo's? Though my code really
> only controlled one servo at a time.
>
> Thanks,
>
> Mike
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
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supposed to be and you keep sending pulses to tell it to be there, it just
waits. With the continuous rotation mod, it will rotate counter-clockwise,
stop, or rotate clockwise depending on the pulse width.
Here is the code for an unmodified Futaba 148 with a BS2sx -- it moves the
servo to 0 degrees, 90 degrees, and 180 degrees. The value on your PULSOUT
command may be different if you have another Basic Stamp version.
'{$stamp bs2sx}
X VAR WORD
Y VAR BYTE
LOW 6
FOR Y = 1 TO 100
DEBUG "Min!",CR
FOR X = 1 TO 100
Pulsout 6, 400
Pause 20
NEXT
LOW 6
DEBUG "Center!",CR
FOR X = 1 TO 100
Pulsout 6,1600
Pause 20
NEXT
LOW 6
DEBUG "Max!",CR
FOR X = 1 TO 100
Pulsout 6,2800
Pause 20
NEXT
LOW 6
NEXT
DEBUG "Done",CR
Original Message
> You didn't say, but are both servos modified for continous rotation? The
code
> you are using is for continous rotation, and I guess you know that, but
I'm
> just wondering if both servos had the modification.
>
> I have a BOE and power 3 servos using the on-board connections. What
power
> supply are you using? If you are using the 9 volt battery and it's fresh,
then
> you can rule out the battery power brownouts. Same goes, if you are using
the
> wall wart, which supplies about 12 volts or more.
>
> In the boe docs, they talk about 2 different versions of the BOE. If you
have
> the later revision, they you shouldn't need any additional hardware to
control
> your servos. I've been having 6 months of success with my BOE.
> Hope this helps a little.
> dave
quickly. I'm impressed! Sorry for my delay in responding, I've
been away all week, but am now back.
For starters, Rodent's right. The Board of Education does have
dedicated servo connectors on board and should (theoretically)
be pre-wired.
The servo's are three-pin connector types with positive (it's red,
anyway!) in the middle. So, hopefully I didn't fry anything by
hooking it up backwards. However… gulp… I now see in the fine
print on the HS-700BB box "Do not directly couple two servos on
one control surface as circuit may become overloaded and burn
out. This servo consumes higher current than standard size
servos." Yikes, that doesn't sound good.
"…one control surface…" ? Would that mean don't hook two
servos up to the BOE, even though it accommodates four
servos?
Rodent writes:
>What you need to do is insult the servo instructions and >find
out what the pulse width is for the neutral (center) >position.
Hmmm, no instructions came with the servo, just some specs
on the back of the box that don't seem to mention pulse widths.
Operating speed, Output torque, yes, pulse width, no.
Paul writes:
>Is there a capacitor inline with the servo? A servo will >draw
enough current to pull the voltage low. When my >student's
servos behave erratically, it is almost always a >missing or
incorrectly installed cap. Use a 3300 uF cap.
No, there's no capacitor inline. Again, I assumed the BOE was
setup to handle all this with no additional doodads, and the
detailed instructions for this setup as featured in their "What's a
Microprocessor?" workbook doesn't mention needing one.
However, the green LED on the BOE does flicker with every
"beat" of the servo trying to work, could that mean a brownout
situation?
How would I interface the capacitor inline? The servo plugs
directly into the servo socket on the BOE.
Thanks for everyone's help, I hope we get to the bottom of this!
the RC receiver. The BOE has a 1-amp regulator, which *should* run two
servos. Might not do it off a 9-volt battery though. Can't you hook up an AC
adapter?
Original Message
The servo's are three-pin connector types with positive (it's red,
anyway!) in the middle. So, hopefully I didn't fry anything by
hooking it up backwards. However. gulp. I now see in the fine
print on the HS-700BB box "Do not directly couple two servos on
one control surface as circuit may become overloaded and burn
out. This servo consumes higher current than standard size
servos." Yikes, that doesn't sound good.
".one control surface." ? Would that mean don't hook two
servos up to the BOE, even though it accommodates four
servos?
About the topic: "Do not directly couple two servos on
one control surface as circuit may become overloaded and burn
out. This servo consumes higher current than standard size
servos."
I presume you must avoid direct action over one control surface (flap,
aileron, rudder, ...) with 2 or more servos because servo motion aren't
100% synchronized and can produce warp forces.
This unbalance motion can produce current overload and/or circuit burn
out.
This is not a problem with independent motions usually found in
robotics.
Usually the big servos are feed with independent batteries (with common
ground) and the RC receiver only supply the small digital control
signal.