Re: Shutter on ROB...

[droege@snapmail.us]

Rob,

OK the first thing to do is to sort out whether it is the MA Servo motor
or not.  Since it only happens on one shutter, just swtich the two and see
if the problem switches.   If it switches, then it is something in the
drive electronics, if it does not, then it is a defective MA servo motor.

If it switches, then there are 6 more ma servo drivers to try on the
board.  You will have to change some code.

If you have an oscilloscope, then you can look at the ma servo pulse. 
Look at drawing M3 to see where the signal comes from at 74ls240 in the
center of the board.  The drive pulse then shows up on the center pin of
the connector to the ma servo.  The servo motor is controlled by the pulse
width of the pulse sent to the motor.  I recall it is of order a 50 to 100
ms wide pulse that must be repeated a few times in order for the motor to
track the command. I think I send the pule 10 or 100 times.  You can look
at the code.

Tom

>
>
> This is really weird.  When I execute a shutter open command to ROB, the
> servo
> moves a small distance, not the commanded distance, and then I receive an
> incorrect packet (7 0x00's) after ~1/4 second.  Generally, if I try long
> enough,
> the command will succeed when the servo moves to the correct distance.
> It's not
> my controlling code, as the problem comes and goes (sometimes) with no
> changes
> on my side.
>
> I used to fix this problem by re-flashing the stamp.  That no longer
> fixed the problem at some point.  I then put in a new stamp, and the
> problem
> went away for a couple of months.  Now, it's back.  I was going into the
> stamp
> code trying to figure out if I could affect the problem by putting delays
> around
> the maservo code.  After 15 to 20 tries of flashing/running/repeat, the
> problem
> went away for a bit, but it came back again.
>
> I think I have some extra servos of the type used which I will try, but
> I'm
> hoping someone might of seen this, or have an idea of what's going on.
> This
> weekend I'll try putting back in the original stamp and re-flashing code.
> Although I'm not completely sure, the problem does appear to be associated
> with
> the stamp part itself (or the servo somehow).  I do have another
> compatible
> stamp part(BS2P24), but am very hesitant to put it in at the cost of $75
> for a
> replacement...
>
> The problem also appears to be only happening to the maservo "22", not
> "14".
>
> I've included a section of my logging, the problem child "22" and a
> successfull
> operation on "14". No other commands are encountering this problem.  This
> run
> ended shortly after by failing to operate the shutter after 10 retries...
>
> 04/11/03 21:46:02 TC[12531]: <02.606> motor_on - turning on motor:
> DEC_DRIVE
> 04/11/03 21:46:02 TC[12531]: <02.608> <48159;?6> Prepped with check bytes
> 04/11/03 21:46:02 TC[12531]: <02.610> <48159;?6> Sent
> 04/11/03 21:46:02 TC[12531]: <02.628> <48159;?6> Received packet in 0.02
> seconds
> 04/11/03 21:46:02 TC[12531]: <02.630> <48159;?6> Check response passed
> 04/11/03 21:46:02 TC[12531]: <02.648> Received <S>
> 04/11/03 21:46:02 TC[12531]: <02.658> <48159;?6> Received packet in 0.05
> seconds
> 04/11/03 21:46:02 TC[12531]: <02.660> <48159;?6> Check response passed
> 04/11/03 21:46:02 TC[12531]: <02.662> maservo - writing 22 with position
> 40
> 04/11/03 21:46:02 TC[12531]: <02.663> <270=:285> Prepped with check bytes
> 04/11/03 21:46:02 TC[12531]: <02.665> <270=:285> Sent
> 04/11/03 21:46:02 TC[12531]: <02.678> <270=:285> Received packet in 0.01
> seconds
> 04/11/03 21:46:02 TC[12531]: <02.680> <270=:285> Check response passed
> 04/11/03 21:46:03 TC[12531]: <03.028> <^@> <0x00> received and tossed 1
> 04/11/03 21:46:03 TC[12531]: <03.030> <^@> <0x00> received and tossed 1
> 04/11/03 21:46:03 TC[12531]: <03.031> <^@> <0x00> received and tossed 1
> 04/11/03 21:46:03 TC[12531]: <03.033> <^@> <0x00> received and tossed 1
> 04/11/03 21:46:03 TC[12531]: <03.034> <^@> <0x00> received and tossed 1
> 04/11/03 21:46:03 TC[12531]: <03.036> <^@> <0x00> received and tossed 1
> 04/11/03 21:46:03 TC[12531]: <03.038> <^@> <0x00> received and tossed 1
> 04/11/03 21:46:05 TC[12531]: <05.668> Timed out waiting for <S>
> 04/11/03 21:46:05 TC[12531]: <05.710> <> Failed to receive complete
> response in
> 3.04 seconds: 1
> 04/11/03 21:46:05 TC[12531]: <05.718> Received a check response failure
> 04/11/03 21:46:05 TC[12531]: <05.719> Executing retry 1
>
> a few retries later:
> 04/11/03 21:46:14 TC[12531]: <14.929> Executing retry 4
> 04/11/03 21:46:14 TC[12531]: <14.938> <270=:289> Prepped with check bytes
> 04/11/03 21:46:14 TC[12531]: <14.939> <270=:289> Sent
> 04/11/03 21:46:14 TC[12531]: <14.958> <270=:289> Received packet in 0.02
> seconds
> 04/11/03 21:46:14 TC[12531]: <14.959> <270=:289> Check response passed
> 04/11/03 21:46:16 TC[12531]: <16.358> Received <S>
> 04/11/03 21:46:16 TC[12531]: <16.368> <270=:289> Received packet in 1.43
> seconds
> 04/11/03 21:46:16 TC[12531]: <16.369> <270=:289> Check response passed
>
>
> A good shutter operation:
>
> 04/11/03 21:46:16 TC[12531]: <16.371> maservo - writing 14 with position
> 55
> 04/11/03 21:46:16 TC[12531]: <16.373> <1709;370> Prepped with check bytes
> 04/11/03 21:46:16 TC[12531]: <16.374> <1709;370> Sent
> 04/11/03 21:46:16 TC[12531]: <16.388> <1709;370> Received packet in 0.01
> seconds
> 04/11/03 21:46:16 TC[12531]: <16.389> <1709;370> Check response passed
> 04/11/03 21:46:17 TC[12531]: <17.798> Received <S>
> 04/11/03 21:46:17 TC[12531]: <17.808> <1709;370> Received packet in 1.43
> seconds
> 04/11/03 21:46:17 TC[12531]: <17.810> <1709;370> Check response passed
>
> Cheers,
> Rob
>
> --
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