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Servo Clock

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lhops
(@lhops)
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Joined: 1 year ago
Posts: 13
Topic starter  

Recently I completed a project that required 3D printing, 28 r/c servos, two PCA9685 and a ESP32.  The project is a Servo Clock that has one servo for each segment of the seven segment digit.  The clock required four digits so 28 servos were needed.  My concern is that the second digit of the minute requires that the servos are activated 1440 times a day. This worries me that the servos will wear out in a short period of time.  My plan is to install a human sensor to turn on the servos when I am present and off when I am not in my office.  I have considered a sensor that would turn off the AC power to the ESP32, but this would require that the clock go thru a complete startup each time which takes about 30 seconds.  Turning the power off to just the servos does not seem to work, when powered back up the PCA9685 becomes confused and the servos become erratic. Maybe a change in the sketch (code) to prevent the the wifi from connecting to the NTP when no one is present.  My C++ experience is not good enough to achieve this.   I was hoping to find someone on this forum that has built something similar and has some suggestions.  I can copy the sketch to anyone that is interested.

lhops


   
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Will
 Will
(@will)
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Joined: 3 years ago
Posts: 2552
 

@lhops

How about installing a radar sensor (or the like) to determine if there's anyone present. But, when no-one is there, instead of shutting down the power, just disable the servos. That is, leave the ESP running but just stop moving the servos. That way you have low power usage and zero servo wear while it's all alone.

When the sensor detects a presence again, it need only move the servos off to their proper angles. That would save the reboot and re-initialization.

Anything seems possible when you don't know what you're talking about.


   
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Ron
 Ron
(@zander)
Father of a miniature Wookie
Joined: 4 years ago
Posts: 7425
 

@will @lhops I have a string of LED lights that I control from a radar sensor. You could use the same idea but you say that turning off the servo power does not work so I am not sure if this idea will work.

First computer 1959. Retired from my own computer company 2004.
Hardware - Expert in 1401, and 360, fairly knowledge in PC plus numerous MPU's and MCU's
Major Languages - Machine language, 360 Macro Assembler, Intel Assembler, PL/I and PL1, Pascal, Basic, C plus numerous job control and scripting languages.
My personal scorecard is now 1 PC hardware fix (circa 1982), 1 open source fix (at age 82), and 2 zero day bugs in a major OS.


   
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lhops
(@lhops)
Member
Joined: 1 year ago
Posts: 13
Topic starter  

@will 

Thank you for your reply.  I did some experiments with the inputs and found that if I remove the clock signal to the PCA9685's the servos remain in there last known time and return to the correct time when re-connected.  In worst case I would have to wait one minute for the PCA's to get their next clock.  I will use your idea of the radar sensor and put a delay of 30 mins in the code to prevent the clock from turning off if the sensor doesn't sense my small movements.  I would like to also thank Ron for his reply. 

This post was modified 1 year ago by lhops

   
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