Will a marriage between the RPi and the 16 channel servo driver ID #815 improve the RPi's ability to control servo driven movements and actions of a small robot? I ask this question, because it is my understanding the RPi runs a time-sliced OS, which I believe is not great for precision timing of actions.
My thinking is the RPi's limited ability to control precise movement does not really in this application as the robot is being build for learning and fun. Therefore, this question falls into the learning aspect of the project.
Any thoughts or advice on this topic would be greatly appreciated.
Cheers
RPi + 16 Channel Servo Driver ID # 815 & robots
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- RussellJames
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- adafruit_support_bill
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
The servo driver would definitely improve your control - particularly when you have multiple servos.
The time between the servo control pulses is not so critical. Most servos will handle a range of 15-30 milliseconds or more. The width of the pulse is the critical part. For most servos, the difference between 0 and 180 degrees is 1 millisecond. So a 0.1 millisecond error equates to about an 18 degree glitch in your movement.
The time between the servo control pulses is not so critical. Most servos will handle a range of 15-30 milliseconds or more. The width of the pulse is the critical part. For most servos, the difference between 0 and 180 degrees is 1 millisecond. So a 0.1 millisecond error equates to about an 18 degree glitch in your movement.
- RussellJames
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
Very helpful,
Thank you.
Thank you.
- Bazilij
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
Hello everybody.
Help me please.
I can't understand what I did wrong.
As instruction says I have installed python-smbus and i2c-tools as well.
Then I have commented "blacklist i2c-bcm2708" in "/etc/modprobe.d/raspi-blacklist.conf" file.
When I trying to search "/dev/i2c-1" by "sudo i2cdetect -y 1" command the error occurs:
"Error: Could not open file `/dev/i2c-1' or `/dev/i2c/1': No such file or directiry".
I have second rev Raspberry Pi.
Could anybody give some advise plaese?
Help me please.
I can't understand what I did wrong.
As instruction says I have installed python-smbus and i2c-tools as well.
Then I have commented "blacklist i2c-bcm2708" in "/etc/modprobe.d/raspi-blacklist.conf" file.
When I trying to search "/dev/i2c-1" by "sudo i2cdetect -y 1" command the error occurs:
"Error: Could not open file `/dev/i2c-1' or `/dev/i2c/1': No such file or directiry".
I have second rev Raspberry Pi.
Could anybody give some advise plaese?
- RussellJames
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
Sorry I cannot give you any technical advice at this time because I am still in the planning stages of my bot.
The best I can do is recommend that you go back, start over and review all the steps to the point of error; be slow and deliberate when you do so.
Good luck.
The best I can do is recommend that you go back, start over and review all the steps to the point of error; be slow and deliberate when you do so.
Good luck.
- adafruit_support_mike
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
@Bazilij: What output do you get from the command:
Code: Select all
ls /dev/i2c*
- Bazilij
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
The result of "ls /dev/i2c*" command.
- Attachments
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- adafruit_support_mike
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
Okay, that shows the OS hasn't created any I2C devices.
Did you reboot after installing the two I2C packages?
Did you reboot after installing the two I2C packages?
- Bazilij
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
Yes, of course.
Some screenshots:
Some screenshots:
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- blacklist-comment.png (3.53 KiB) Viewed 412 times
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- i2c-tools.png (4.56 KiB) Viewed 412 times
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- python-smbus.png (4.39 KiB) Viewed 412 times
- Bazilij
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
And the error:
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- i2cdetect.png (2.79 KiB) Viewed 411 times
- adafruit_support_mike
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
What does your /etc/modules file look like?
- Bazilij
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
Modules file:
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- modules.png (4.73 KiB) Viewed 399 times
- adafruit_support_mike
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
Bingo..
It looks like you missed the step at the beginning of the tutorial where you add these two lines to /etc/modules:
It looks like you missed the step at the beginning of the tutorial where you add these two lines to /etc/modules:
Code: Select all
i2c-bcm2708
i2c-dev
- Bazilij
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- Joined: Mon Oct 06, 2014 8:48 am
- adafruit_support_mike
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Re: RPi + 16 Channel Servo Driver ID # 815 & robots
Glad to hear it's working for you. Happy hacking!
Forum rules
Talk about Adafruit Raspberry Pi® accessories! Please do not ask for Linux support, this is for Adafruit products only! For Raspberry Pi help please visit: http://www.raspberrypi.org/phpBB3/
Talk about Adafruit Raspberry Pi® accessories! Please do not ask for Linux support, this is for Adafruit products only! For Raspberry Pi help please visit: http://www.raspberrypi.org/phpBB3/