Connecting a Servo to the OpenCR

[pitosalas]

Looking around the source code and googling around, it seems to be that the Turtlebot3 / OpenCR board is set up to accept a servo connector. I see there's a package called servo etc. My question is where on the OpenCR board should we attach the servo connector? THank you!

[shiba-8ro]

Hi,
If it is meaning PWM servo, ROBOTIS e-manual has the Pin assign description.
https://emanual.robotis.com/docs/en/parts/controller/opencr10/#pwm

[pitosalas]

I see. Can you say whether how to enable the topic via rosserial on the OpenCR or does that happen "automatically"?

[ROBOTIS-Will]

Hi,
This OpenCR ROS examples may help you to implement the publisher / subscriber for PWM motor control.
Similar sub/pubs are implemented in the TurtleBot3 ROS example.

[pitosalas]

Thank you. I cannot locate the OpenCR ROS examples. And the TB3 ROS example shows the ROS side. I am asking about the OpenCR side. For example: `self.bumper_sub = rospy.Subscriber('sensor_state', SensorState, self.get_bumper, queue_size = 1)` I need the code on the OpenCR side that would publish sensor_state Any pointers? Pito Salas Faculty, Computer Science Brandeis University

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On Apr 12, 2022, at 5:06 AM, Will Son ***@***.***> wrote: Hi, This OpenCR ROS examples may help you to implement the publisher / subscriber for PWM motor control. Similar sub/pubs are implemented in the TurtleBot3 ROS example. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you authored the thread.

[ROBOTIS-Will]

@pitosalas
I'm sorry about the delayed response.
ROS examples in OpenCR board manager have those pub/sub implmentations.
For example, the bumper status is published via "bumper" topic in the example below.
https://github.com/ROBOTIS-GIT/OpenCR/blob/master/arduino/opencr_arduino/opencr/libraries/ROS/examples/02.%20Sensors/a_bumper/a_bumper.ino#L58

Similarly, the TurtleBot3 sensor state message is published in the below.
https://github.com/ROBOTIS-GIT/OpenCR/blob/master/arduino/opencr_arduino/opencr/libraries/turtlebot3/examples/turtlebot3_burger/turtlebot3_core/turtlebot3_core.ino#L258

Thank you.

[pitosalas]

Thanks… Is there a developer guide for OpenCR? Because I understand the code you linked me to but I dont know where the “main loop” is for opencr where I would add rosserial code to subscribe to a topic and send the right commands to the servo. Pito Salas Faculty, Computer Science Brandeis University

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On Apr 20, 2022, at 10:45 PM, Will Son ***@***.***> wrote: @pitosalas I'm sorry about the delayed response. ROS examples in OpenCR board manager have those pub/sub implmentations. For example, the bumper status is published via "bumper" topic in the example below. https://github.com/ROBOTIS-GIT/OpenCR/blob/master/arduino/opencr_arduino/opencr/libraries/ROS/examples/02.%20Sensors/a_bumper/a_bumper.ino#L58 Thank you. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you were mentioned.