usb servo controler, dying servo's, and a non comunication boe board..... yikks

stamp_demon

Well about three weeks ago I ordered a usb servo controller. Tonight I decided to play with it. So after reading threw the pdf that I had downloaded a few times. I tested out some sample code on a homeowrk board I had.... it all worked out fine. I then tryed to get it to work with two servos, again no trouble. So I decided to use in on my boebot. I ajusted the pw times for the bs2px. Tested it again, And it seemed fine. Everything seemed to be working well. Then after about 10-15 mins of running my bot, the servo's started to shutter, then stop completly. I tryed two new servos I have. They started out fine, then the same thing. With one exception. One servo still works great, but the other is dead. I now have three dead servos. And for some reason the boe board wil not comunicate with the pc anymore. I recharged the batts, same thing.
·Oh and I am using tow different batt sources, 6v for the bscpx, and 7v for the servo board, just as it says..... This all sadens me, as it will be a pretty long time before I can replace everything...... Chers.. _Duane

Tricky Nekro

Check if the BOE battery is running low... It's the only reason for not communicating with the PC in standar conditions...



Provas, Greece

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stamp_demon

I recharged the battery, but am still having the same trouble.

allanlane5

"Recharged the Batts" -- are you SURE you've got 6 volts going to the BS2? If you're using 4 Ni-Cd, or even 4 Ni-Mh batteries to drive the BS2, then 4 * 1.2 == 4.8 volts, not 6. The BS2 won't work very well at 4.8 volts. And after very little time on the batteries they would drop to the point where it won't work at all.

stamp_demon

Yes, I know for a fact that I am getting 6v. I am using a 5 pack of nimhi @ 1.2v. I have used this pach on several ocasions with no trouble. And checked the voltage after charging.....·

stamp_demon

We'll I dont know why, but I am now able to comunicate with the pc. This is good. However I still have three of four servos dead. They all worked fine before the tryed using the servo controller... This is pretty fustrating, I'm about an inch away from trashing it all.

Beau Schwabe

stamp_demon,

Can you provide us with the code that you are using?

Are the servos that you are using from Parallax or from somewhere else?


The reason that I ask, is because the Parallax servo's are designed to accept
a pulse width that goes outside of the 1-2mS servo standard to obtain a further
degree of rotational freedom. If the code is geared for a Parallax servo and
you are not using a Parallax servo, the non Parallax servo could experience
issues in this situation.

First I would try to find out the cause of the intermittent PC communication problems
before I proceeded with anything else.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

stamp_demon

The servo,s I am using are from parallax. And they code is from the pdf downloaded from your site. My only changes were to set it for two servos. And the pulswith was changed to 2250 for the bs2px.

I forgot to say, I belive I found my comm trouble. A lead seemed to have come kinda loose from my batt pack. I repaired the problem. It now seems to be fine..... I have succesfully connected three times no trouble.

I am now only left with the servo trouble. I may hofully be able to order three or fopur this next week to replace all the dammaged one's. But I want to know that they will be fine with the servo controller. Two of them were new, tested to work great, thne never used untill yesterday. The other two were on the boebot. Thou they have been in use for a while now, I have never had any trouble with them.

Post Edited (stamp_demon) : 8/13/2006 9:06:33 PM GMT

Beau Schwabe

stamp_demon,

If you are using a usb servo controller, you should not need to change the pulsewidth based on the flavor of Stamp you are using since
the servo controller is designed to maintain this independently.

you said...

"...And the pulswith was changed to 2250 for the bs2px..."

Look at the documentation covering the signals that the servo controller expects to see.

www.parallax.com/dl/docs/prod/motors/ServoController.pdf


The range that you are specifying at 2250 should only be between 250 and 1250 that corresponds to 0 - 180 Deg of rotation. The resolution
is in 2uS units so 250 is equal to a 500uS pulse where as 1250 is equal to a 2500uS pulse.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

stamp_demon

Yikes, I thought thouse values were used for bs2 only.... I guess that is why all my servo's are fryed.....

·I changed the values, now my only working servo is no longer working. I set pw to 1250 as you segested... Now I'm getting nothing at all from any of them...

·I should have never ordered one... What was I thinking?!?

·Anyway th nak you for all your help. _Duane

allanlane5

Servo electronics really like a source voltage between 5 and 6 volts. Some will run at 7.2, but it really shouldn't go over that. Check your voltage to the Servo's with a voltmeter to make really-really sure.

stamp_demon

In the instruction for the servo controller is ask that it have a 7-9v sourse, of wich I have 7.2v.. and the bs2 requires·6 of course. This is why it ask for two batts sources one for the controller, and one for the boe board. Now I agree with you, I have never gave over 5v to any servo. But having read that it requires 7-9v I used a 6cell pack... 7,2v. I asumed that it would regulate the propper amount to the servos. And I am sure that it is.... I'm guess that it is me that is the problem. After I replace the servo's. When ever I can... I will most liklly not use the controler ever again... I am obviouslly not possing the inteligents to do so.

·Thank you very much, Duane.

stamp_demon

Okay I was wrong. I thought I had read that the max voltage was 9v... It is 7.5v. However I checked my batt level with a meter.. I'm only getting 7.4v Although close, it should be fine.