Problem Controlling Servo

Started by tieutaydoc May 2, 2006
Hi everyone. I got my bx-24 for a while now but I haven't tried using
it to control servos. I don't have any experience with servo before
but from what I have read I thought it would be a breeze but I am
having the weirdest problem.

I used the servo codes provided on the basicx website. I've tried
this with 2 different type of servos: Tower Pro SG90 and GWS naro and
got teh same problem. At first when I ran the code it just moved the
servo in one direction and it get stuck there. After trying different
numbers for the number of steps and positions it woudl move in one
direction to a point then move back ward and forward again,
flutuating at one position.

After some invistigating I find that something is causing the bx-24
to reset after pulsing out. I checked the servos on the things and it
seems to work fine so I ruled that out. If anyone can help me out
with this, I would appreciate it very much. Thanks in advance.

Jimmy
Jimmy,
You need a bigger power supply for your servos. a four C-Cell battery
pack should provide the servos with the current they need.

The older BX-24 chips will reset when the voltage falls below 4.7v, the
newer BX-24p chips reset at 2.7v.
Chris

----- Original Message -----
From: "tieutaydoc"
To:
Sent: Monday, May 01, 2006 9:18 PM
Subject: [BasicX] Problem Controlling Servo
> Hi everyone. I got my bx-24 for a while now but I haven't tried using
> it to control servos. I don't have any experience with servo before
> but from what I have read I thought it would be a breeze but I am
> having the weirdest problem.
>
> I used the servo codes provided on the basicx website. I've tried
> this with 2 different type of servos: Tower Pro SG90 and GWS naro and
> got teh same problem. At first when I ran the code it just moved the
> servo in one direction and it get stuck there. After trying different
> numbers for the number of steps and positions it woudl move in one
> direction to a point then move back ward and forward again,
> flutuating at one position.
>
> After some invistigating I find that something is causing the bx-24
> to reset after pulsing out. I checked the servos on the things and it
> seems to work fine so I ruled that out. If anyone can help me out
> with this, I would appreciate it very much. Thanks in advance.
>
> Jimmy
>
Hi Jimmy,
Your observation that "...something is causing the BX-24
to reset..." is a clue. The BX-24 will reset itself if
the input voltage goes below 4.75 VDC.
(see schematic LP2951 (U3))

(datasheet) ERROR DETECTION COMPARATOR OUTPUT
The comparator produces a logic low output whenever the
LP2951 output falls out of regulation by more than
approximately 5%.

It is likely that the extra load of the servo motors is
"pulling down" on your power supply. Try powering your
BX-24 from a separate power supply. The "grounds" of both
supplies must be tied together.

Eric
----- Original Message -----
From: tieutaydoc
To: b...
Sent: Monday, May 01, 2006 9:18 PM
Subject: [BasicX] Problem Controlling Servo
Hi everyone. I got my bx-24 for a while now but I haven't tried using
it to control servos. I don't have any experience with servo before
but from what I have read I thought it would be a breeze but I am
having the weirdest problem.

I used the servo codes provided on the basicx website. I've tried
this with 2 different type of servos: Tower Pro SG90 and GWS naro and
got teh same problem. At first when I ran the code it just moved the
servo in one direction and it get stuck there. After trying different
numbers for the number of steps and positions it woudl move in one
direction to a point then move back ward and forward again,
flutuating at one position.

After some invistigating I find that something is causing the bx-24
to reset after pulsing out. I checked the servos on the things and it
seems to work fine so I ruled that out. If anyone can help me out
with this, I would appreciate it very much. Thanks in advance.

Jimmy

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