Servos on SX48/52 Proto Board?

jcpole

Hi all...

I've got a bunch of SX48/52 proto boards that I have used to build a custom brain for a combat robot I'm designing.· My programs work just fine, and I'm at the point where I need to actually make the little guy move, and I've hit a snag.· Is there anything special that I need to do to enable the servo connectors on these boards?· The schematics seem to show that they are already hardwired, but I don't get anything when I connect servos to the boards.

The schematics also mention a connection (actually, several connections) for Vsvo.· I seem to recall reading somewhere that one shouldn't use regulated power for servos and DC motors - do I need to connect an alternate power source for the servos?

I know that my servo logic is good because I tested the basic program (movement only) on a BS2px.· The boards just don't seem to be providing any power to the servo connectors.

Thanks...

Jamie

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Jamie C. Pole
Principal Consultant
J.C. Pole & Associates, Inc.
http://www.jcpa.com/

PJMonty

Jamie,

As I recall, the power switch switch is a three position switch. Position 0 = OFF, position 1 = Power to logic only, position 2 = power to logic and servos.

I use regulated power for servos all the time, but that's because I'm driving them from a big 100 VAC powered supply. If you're running off batteries for your bot, then giving them raw battery power is probably better. Just make sure the battery voltage doesn't exceed the allowed voltage for the servos.

In addition, you can't really power them from the regulator on the proto board since it's a linear regulator limited to about 1 AMP - but only with a heatsink the size of Cleveland. Run a bunch of servos and you;ll get a burning hot voltage regulator in no time.

Thanks, PeterM

Mike Cook

In addition to Peter's info make sure that you have selected the voltage source for the four 3-pin headers. To the right of the last servo connector, is a spot for a horizontal 3-pin header. This will allow you to select VDD or VIN for the servo headers. As shown in the attached picture this board is set to supply VDD to the servo connector.·In addition·you will need to connect the signal pin of the three pin servo header to the SX. In the attached photo, the white wire connected to servo header '0' is connected to RA.0

SX Proto Board - Servo Header Layout:

                           V V V
                           D s I
                           D v N
               -----------   o
VSS (GROUND)   | . . . . | . . . 
+Vsvo          | . . . . | 
SIGNAL         | . . . . | 
               -----------
                 3 2 1 0 

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Mike

Post Edited (Mike Cook) : 12/5/2006 2:12:29 PM GMT

jcpole

Thanks Peter and Mike!

I knew that I had to have been missing something boneheaded...· :-)·

It never even occurred to me that a jumper was needed to select the voltage source - of course, that would explain why there's no continuity across those pins, wouldn't it?· ;-)· It's always the simple things - I practically have a neural network running on these SXs, and I get strung up by a missing voltage select jumper.· Gotta love it...

As far as the amperage for the servos, I was wondering about that...

Thanks again...

Jamie

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--
Jamie C. Pole
Principal Consultant
J.C. Pole & Associates, Inc.
http://www.jcpa.com/