Servo motors? How do you determine unknown pin-outs on a servo motor, such as that on the inside of my old Minolta camera? Well, I’m still not exactly sure, but this is a helpful resource.
20160704/http://www.jameco.com/Jameco/workshop/howitworks/how-servo-motors-work.html
So, how about a Raspberry Pi oscilloscope? That should help you diagnose the connection.
Cool! Raspberry Pi oscilloscope. Well, this isn’t actually particular to the Raspberry Pi, but it works with the Raspberry Pi. If you ask me, I’d go for the micro one. I like the small size, and it is fast enough for my purposes.
20160704/https://www.raspberrypi.org/blog/bitscope-micro/
20160704/http://www.bitscope.com/pi/
20160704/http://www.bitscope.com/
20160704/http://www.bitscope.com/design/?p=machine
20160704/http://www.bitscope.com/pi/
20160704/http://www.bitscope.com/product/BS05/
20160704/http://www.bitscope.com/product/BS10/
Oh, hey! Let’s revisit that other article referenced above on servo motors. It says the standard time versus angle is represented in the chart. And, that’s also what I’ve got from the other source I found. Well, that sounds pretty good then. I’ve got reliable references to work with.
20160704/http://www.societyofrobots.com/actuators_servos.shtml
Yes, in fact, it seems I’ve got a very reliable message emerging. Here are the key points:
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Standard timing is as follows.
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The pulse period is 20 ms.
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1 ms pulse moves the servo to zero degrees.
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2 ms pulse moves the servo to 180 degrees.
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What if the pulse is shorter or longer than this? Some servos will move to the respective min or max position, others will go out of order, and still others will do nothing.
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It seems the +V power pin is always in the center.
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If you mix up the ground and signal pins, this may not cause any actual damage to the servo motor. However, I’ve also seen another source that warns strongly against mixing up the red and black pins. Plus, my warning about about the behavior of nonstandard signals still applies.
Are there any servos that don’t use standard timing? Apparently these are very rare. Very very rare. So, the only thing left that I need to do is find a way to generate the proper pulsed signal and find out which pins are which. Both such activities are greatly facilitated with the help of an oscilloscope.
Oh, yeah, and that reminds me. Composite video input for a Raspberry Pi? Record from a composite video source? Well, as it turns out, I haven’t seen many recommendations for using the GPIO pins to do this job. Mostly they recommend using a USB 2.0 UVC-compliant frame grabber. Of course this does come with the problem of not being able to sample enhanced bandwidth Apple II video signals.
20160704/https://www.raspberrypi.org/forums/viewtopic.php?f=63&t=20159
20160704/https://www.raspberrypi.org/forums/viewtopic.php?f=38&t=7748
Keep searching!
JJJ TODO LINK to my updated articles.