Still under development Starting to add XL-430 servo

• pyservos
  • ServoSerial - half duplex hardware serial interface using DTR from a USB serial port
  • PiServoSerial - half duplex hardware serial interface using a HW pin
  • utils - misc
  • XL320 - register/command/error definitions for Dynamixel's XL-320 servo
  • AX12 - register/command/error definitions for Dynamixel's AX-12A servo
  • XL430 - register/command/error definitions for Dynamixel's AX-12A servo

The suggested way to install this is via the pip command as follows::

pip install pyservos

I am currently using poetry for my library and using pyproject.toml. To submit git pulls, clone the repository and set it up as follows:

git clone https://github.com/MultipedRobotics/pyservos
cd pyservos
poetry install
poety run pytest

The \bin directory has a number of useful programs to set servo position or ID number. Just run the command with the --help flag to see how to use it.

• servoAX12
• servoXL320 (not implemented)
• servoXL430 (not implemented)

The above commands have the following format:

• servoXXX
  • ping: find servos on bus, ID[int|None]
  • reboot: reboot a servo, ID[int|None]
  • reset: reset a servo, ID[int], level[int]
  • angle: set new angle in degrees or radians, angle[float], radians[True|False]
  • baudrate: set new baudrate, rate[int]
  • id: set new ID, current_id[int], new_id[int]
• Values
  • ID: 1-254
  • reset level: 1 (all), 2(all but ID), 3 (all but ID and baudrate)
  • angle: 0-300 degrees
  • rate: 1000000 is default
  • None: if you leave out the value, there is a default that occurs which is safe

• AX-12A Servo
• XL-320 Servo
• XL-430 Servo

A simple example to turn the servo and turn the LED on using a USB serial converter:

# Run an AX-12 servo
from pyservos.servo_serial import ServoSerial
from pyservos.ax12 import AX12

serial = ServoSerial('/dev/tty.usbserial')  # tell it what port you want to use
# serial = ServoSerial('dummy')  # use a dummy serial interface for testing
serial.open()

ax = AX12()
pkt = ax.makeServoPacket(1, 158.6)  # move servo 1 to 158.6 degrees
ret = serial.sendPkt(pkt)  # send packet, I don't do anything with the returned status packet

pkt = ax.makeLEDPacket(1, AX12.LED_ON)
ret = serial.sendPkt(pkt)

Although I have made some packet creators (like LED and Servo), you can make your own using the basic makeWritePacket and makeReadPacket.

# Run an XL-320 servo
from pyservos.xl320 import XL320
from pyservos.utils import angle2int

xl = XL320()

# let's make our own servo packet that sends servo 3 to 220.1 degrees
ID = 3
reg = XL320.GOAL_POSITION
params = angle2int(220.1)  # convert 220.1 degrees to an int between 0-1023
pkt = xl.makeWritePacket(ID, reg, params)

Here are some example robots

I haven't used these, but they seem good:

• c++: libdynamixel

Copyright (c) 2016 Kevin J. Walchko

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