Servo (Product ID: 1404) does not go into the released state

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TeTue
 
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Servo (Product ID: 1404) does not go into the released state

Post by TeTue »

Hello,

I'm trying to do some basic functions with the servo motor:
https://www.adafruit.com/product/1404 and the board "Adafruit QT Py ESP32-S2"

I have only connected the red (power), brown (gnd) and orange (signal) cables and execute the following code:

Code: Select all

import time
import board
import pwmio
from adafruit_motor import servo

# create a PWMOut object on Pin A2.
pwm = pwmio.PWMOut(board.A2, duty_cycle=2 ** 15, frequency=50)

# Create a servo object, my_servo.
my_servo = servo.Servo(pwm)

while True:
    for angle in range(0, 180, 5):  # 0 - 180 degrees, 5 degrees at a time.
        my_servo.angle = angle
        time.sleep(0.05)
    for angle in range(180, 0, -5): # 180 - 0 degrees, 5 degrees at a time.
        my_servo.angle = angle
        time.sleep(0.05)
    break
my_servo.angle = None
time.sleep(0.05)
print("stop")
from: https://learn.adafruit.com/using-servos ... vo-control

The problem now is that I cannot get the servo to assume a “release” status in any setting. This means that I can then move it again by hand. The reason for this is this project (https://learn.adafruit.com/two-way-disp ... ck-servos#), which I would like to implement.

I have already rebuilt the bootloader and tried versions
- adafruit-circuitpython-adafruit_qtpy_esp32s2-de_DE-8.2.10.uf2
- adafruit-circuitpython-adafruit_qtpy_esp32s2-en_US-9.2.3.uf2
- adafruit-circuitpython-adafruit_qtpy_esp32s2-de_DE-9.2.3.uf

What am I missing?

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adafruit_support_carter
 
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Re: Servo (Product ID: 1404) does not go into the released state

Post by adafruit_support_carter »

What is the servo's behavior if you connect the signal wire to GND? Can you then move it by hand?

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TeTue
 
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Re: Servo (Product ID: 1404) does not go into the released state

Post by TeTue »

I don't think I've quite got the process right. If no program is running (empty program with a print) I can move the servo normally by hand. When I run the above program, I can no longer move the servo. It remains fixed in the last position reached. I can also hear a low humming noise the whole time.

I set signal pin to gnd anyway. It moves to a random position (looks like random). and I still can't move it by hand when the program has run from above

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Re: Servo (Product ID: 1404) does not go into the released state

Post by adafruit_support_carter »

I set signal pin to gnd anyway. It moves to a random position (looks like random). and I still can't move it by hand when the program has run from above
This would generally indicate the servo does not have a turn off behavior. Wiring the pin the GND has the same effect as setting the angle to None in code. From the point of view of the servo, it's the same signal.

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TeTue
 
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Re: Servo (Product ID: 1404) does not go into the released state

Post by TeTue »

I didn't realize that at the beginning, sorry. I tried it again and after my test program, I plugged the cable to ground. but it won't move with hand

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adafruit_support_bill
 
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Re: Servo (Product ID: 1404) does not go into the released state

Post by adafruit_support_bill »

That is something we have seen from several manufacturers recently. Some are quietly replacing old analog control circuits with digital ones that 'remember' the last commanded position for as long as they are powered. The 'released' state was a well-known but 'undocumented feature' of the analog circuits, so the change does not appear in any spec sheet. We probably need to re-visit some older tutorials and add warnings about that.

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TeTue
 
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Re: Servo (Product ID: 1404) does not go into the released state

Post by TeTue »

That sounds annoying. Do I now have a chance of realizing my project?

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Re: Servo (Product ID: 1404) does not go into the released state

Post by adafruit_support_bill »

One way would be to cut power to the servo. You could use the touch sensor to briefly turn off the gate of a MOSFET controlling power to the servo. https://www.adafruit.com/product/5648

A normally-closed pushbutton on the handle would be less elegant - but could accomplish the same thing.

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TeTue
 
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Re: Servo (Product ID: 1404) does not go into the released state

Post by TeTue »

o_O

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adafruit_support_bill
 
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Re: Servo (Product ID: 1404) does not go into the released state

Post by adafruit_support_bill »

I mentioned the issue to the authors of the tutorial you are following. They may have some suggestions as well.

Looking around, there are not a lot of analog feedback servos out there. Pololu carries several models from the Feetech line that have analog feedback. I don't know whether these have a 'release' state or not:
https://www.pololu.com/category/23/rc-servos

If you are not able to make use of the analog feedback servos you purchased from Adafruit, we can offer a refund. You can contact [email protected] with a link to this thread to arrange it.

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TeTue
 
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Re: Servo (Product ID: 1404) does not go into the released state

Post by TeTue »

Thanks for checking. I had already looked for alternative servos. However, I never find the information whether there is a "release" status. I don't really understand why. I actually find this very useful also in model building.

many thanks for the support

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