Timeline for Multiple Servo, Move when not powered on
Current License: CC BY-SA 3.0
17 events
| when toggle format | what | by | license | comment | |
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| Jul 26, 2017 at 7:55 | answer | added | Bruce Abbott | timeline score: 1 | |
| Jul 26, 2017 at 6:09 | comment | added | Edwin Fairchild | I wish I could get the schematics of these 32 servo controllers on ebay apprently you can send it commands and tell it what servo to move how much and how fast | |
| Jul 26, 2017 at 6:04 | comment | added | Edwin Fairchild | Also since the servos are moving a very light weight arm I am not concerned with them not maintaining their position since the arm is so light weight it just does not move the servo when powered off. But like I mentioned the circuit works fine when one digit is plugged into the pcb but once I have a mess of wires with all 28 servos plugged in I get erratic behavior. My guess is the power lines are getting noisy, I looked at them on the scope and they are getting noisy, most likely it is the ground plane. Oh nad the servos are powered by a 7806, the micro controller by a 7805 via 12V 2A input. | |
| Jul 26, 2017 at 5:59 | comment | added | Edwin Fairchild | The choice to use the decoder was simply because I had the chip lying around and I figured I could avoid a lot of if-statements or switch cases in my program by just letting the IC do it, not to mention I cut down on pins used, 4 for the bcd decoder versus 7 I would have to use to drive the MOSFETs via the micro controller. Furthermore I turn the servos off because when they are left on there is a constant jitter , not to mention because of the design if I left them on I would move servos that I did not want to move. | |
| Jul 26, 2017 at 5:36 | comment | added | Jack Creasey | @Mayank. An analog multiplexer won't work (for the signal). If you have VCC applied to a servo and no incoming frames (the signal) the servo is in free mode (it will be low current). If you apply the signal frames (typically 50 -300 Hz depending on type) then the servo will hold or seek to the PWM signal defined. | |
| S Jul 26, 2017 at 5:32 | history | suggested | Mayank | CC BY-SA 3.0 |
corrected spelling
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| Jul 26, 2017 at 5:19 | comment | added | Mayank | I agree with @JackCreasey, the decoding could be simply done by controller and decoder is not necessary at all. | |
| Jul 26, 2017 at 5:17 | comment | added | Mayank | Just for better understanding and being able to provide a better solution, can you explain why you chose this design? I mean is it that your application is very power sensitive? It's because I think a better solution would be to use just analog multiplexer in cascade mode and just 5 mux should make the circuit work. Although I am not sure about it. | |
| Jul 26, 2017 at 5:10 | comment | added | Jack Creasey | Your servos need VCC and ground all the time. Switching VCC on and off will upset the servo internal control. All you need to do is control the PWM signal to each segment for the digits. Since you actually only have two positions for each servo, you could simply switch the on/off PWM to each segment from simple digital ports and run two PWMs as interrupt driven activation. You don't need a decoder at all...this could all be simply done in software. | |
| Jul 26, 2017 at 5:09 | comment | added | Mayank | I don't know what motivated someone to downvote. Seems like a fair question to me. Anyway, coming to point. Can you share more details, I mean the MOSFET number and the servo details? Are all the servos powered via 7805 IC? | |
| Jul 26, 2017 at 5:03 | review | Suggested edits | |||
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| S Jul 26, 2017 at 5:01 | history | suggested | Mayank | CC BY-SA 3.0 |
corrected spelling
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| Jul 26, 2017 at 5:00 | review | Suggested edits | |||
| S Jul 26, 2017 at 5:01 | |||||
| Jul 26, 2017 at 4:59 | history | edited | Edwin Fairchild | CC BY-SA 3.0 |
added 130 characters in body
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| Jul 26, 2017 at 4:55 | comment | added | Edwin Fairchild | what justifies a down vote? Did I ask improperly? Please correct me so that I may ask my questions as they should be asked, otherwise I will never learn. | |
| Jul 26, 2017 at 4:33 | history | edited | Edwin Fairchild | CC BY-SA 3.0 |
added 93 characters in body
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| Jul 26, 2017 at 4:27 | history | asked | Edwin Fairchild | CC BY-SA 3.0 |