RPistepper is a library control stepper motors using a Raspberry Pi and a transistor array
Project description
RPistepper
==========
RPistepper is a library containing: \* A class to control a stepper
motor with a RPi. \* A function to execute a zig-zag motion with two
motors. \* A function to execute a square\_spiral motion with two
motors.
Wiring
------
In our setup, the power to the motors (Vm) is supplied with the 5V pins
of the RPi, the grounding of the coils is controlled with a
`ULN2803A <http://www.ti.com/lit/ds/symlink/uln2803a.pdf>`__ transistor
array.
.. figure:: pinout.png
:alt: Example setup
Alt text
Conections RPi - ULN2803A:
^^^^^^^^^^^^^^^^^^^^^^^^^^
+-----------------+------------+
| RPi Pin (BCM) | ULN2803A |
+=================+============+
| 17 | 1B |
+-----------------+------------+
| 27 | 2B |
+-----------------+------------+
| 10 | 3B |
+-----------------+------------+
| 9 | 4B |
+-----------------+------------+
| 14 | 5B |
+-----------------+------------+
| 15 | 6B |
+-----------------+------------+
| 23 | 7B |
+-----------------+------------+
| 24 | 8B |
+-----------------+------------+
Conections ULN2803A - Motors:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+------------+---------------------+
| ULN2803A | Motors |
+============+=====================+
| 1B | Motor\_1 Coil\_A1 |
+------------+---------------------+
| 2B | Motor\_1 Coil\_A2 |
+------------+---------------------+
| 3B | Motor\_1 Coil\_B1 |
+------------+---------------------+
| 4B | Motor\_1 Coil\_B2 |
+------------+---------------------+
| 5B | Motor\_2 Coil\_A1 |
+------------+---------------------+
| 6B | Motor\_2 Coil\_A2 |
+------------+---------------------+
| 7B | Motor\_2 Coil\_B1 |
+------------+---------------------+
| 8B | Motor\_2 Coil\_B2 |
+------------+---------------------+
In this case, two motors were attached to the ULN2803A.
Usage
-----
class RPiStepper
~~~~~~~~~~~~~~~~
This class allows the user to control a 6 pin stepper motor using 4 GPIO
pins of a RPi.
Software uses BCM mode for pin indexing.
This class is best used with the 'with' statement to properly handle the
cleanup of the GPIOs.
self.steps is a property of this class that will get the number of steps
taken from the initial position or set to a specific step, similar to
self.move.
In order to save power, it's advised to call self.release() when the
motor is idle.
Arguments are a list with the 4 pins (Coil\_A1, Coil\_A2, Coil\_B1,
Coil\_B2), the delay between steps (default = 20ms) and verbose to
display reports on the motor movements, the last two are optional. e.g:
.. code:: python
import RPistepper as stp
M1_pins = [17, 27, 10, 9]
with stp.RPiStepper(M1_pins) as M1:
for i in range(10): # moves 20 steps,release and wait
print M1
M1.move(20)
M1.release()
raw_input('enter to execute next step')
If the class is instantiated normally, use the method ``cleanup`` prior
to closing the application to close the GPIO resources. Also, if it's
important to go back to the initial position when finishing the routine,
use the method ``reset``.
.. code:: python
import RPistepper as stp
M1_pins = [17, 27, 10, 9]
M1 = stp.RPiStepper(M1_pins)
for i in range(10): # moves 20 steps,release and wait
print M1
M1.move(20)
M1.release()
raw_input('enter to execute next step')
M1.reset()
M1.cleanup()
Methods
^^^^^^^
Currently there are four implemented methods:
.. code:: python
def move(self, steps):
'''
Moves the motor 'steps' steps. Negative steps moves the motor backwards
'''
.. code:: python
def release(self):
'''
Sets all pins low. Power saving mode
'''
.. code:: python
def reset(self):
'''
Returns the motor to it's initial position
'''
.. code:: python
def cleanup(self):
'''
Cleans the GPIO resources
'''
The main method is ``move``, which moves the motor the desired number of
steps
steps property
^^^^^^^^^^^^^^
It's possible to check the motor position or manually set the desired
step using the ``steps`` property:
.. code:: python
import RPistepper as stp
M1_pins = [17, 27, 10, 9]
with stp.RPiStepper(M1_pins) as M1:
for i in range(10): # moves 20 steps,release and wait
print M1.steps
M1.steps = 20*i
M1.release()
raw_input('enter to execute next step')
M1.reset()
Attributes
^^^^^^^^^^
This class haves the following attributes:
+-----------------+------------------------------------------------+
| Attribute | Data |
+=================+================================================+
| DELAY | Time between steps |
+-----------------+------------------------------------------------+
| VERBOSE | Display motor data on screen |
+-----------------+------------------------------------------------+
| PINS | GPIOs used by the instance |
+-----------------+------------------------------------------------+
| actual\_state | A list with the status of the coils (on/off) |
+-----------------+------------------------------------------------+
functions
~~~~~~~~~
These two functions executes pre determined movements and requires two
stepper motor objects:
.. code:: python
def zig_zag(motor1, motor2, amp1, amp2, delay=None):
'''
Executes a zig-zag movement with two RPistepper objects.
Arguments are: motor1 and motor2 objects and amp1, amp2, the amplitude
of movement, a tuple (step, rep) representing the number of steps per
iteration and the number of iterations of the following algorithm:
Repeat rep1 times:
1. Moves motor 2 step2*rep2 steps forward
2. Moves motor 1 step1 steps forward
3. Moves motor 2 step2*rep2 steps backwards
4. Moves motor 1 step1 steps forward
Reset to initial state
Release the motors
It's possible to change the delay between steps with the 'delay' argument
'''
.. code:: python
def square_spiral(motor1, motor2, amplitude, delay=None):
'''
Executes a square spiral movement with two RPistepper objects.
Arguments are: motor1 and motor2 objects and the amplitude of movement,
a tuple (step, rep) representing the number of steps per iteration and
the number of iterations of the following algorithm:
for i in range(rep):
1. Moves motor 2 to position i
2. Moves motor 1 to position i
3. Moves motor 1 to position -i
4. Moves motor 2 to position -i
Reset to initial state
Release the motors
It's possible to change the delay between steps with the 'delay' argument
'''
==========
RPistepper is a library containing: \* A class to control a stepper
motor with a RPi. \* A function to execute a zig-zag motion with two
motors. \* A function to execute a square\_spiral motion with two
motors.
Wiring
------
In our setup, the power to the motors (Vm) is supplied with the 5V pins
of the RPi, the grounding of the coils is controlled with a
`ULN2803A <http://www.ti.com/lit/ds/symlink/uln2803a.pdf>`__ transistor
array.
.. figure:: pinout.png
:alt: Example setup
Alt text
Conections RPi - ULN2803A:
^^^^^^^^^^^^^^^^^^^^^^^^^^
+-----------------+------------+
| RPi Pin (BCM) | ULN2803A |
+=================+============+
| 17 | 1B |
+-----------------+------------+
| 27 | 2B |
+-----------------+------------+
| 10 | 3B |
+-----------------+------------+
| 9 | 4B |
+-----------------+------------+
| 14 | 5B |
+-----------------+------------+
| 15 | 6B |
+-----------------+------------+
| 23 | 7B |
+-----------------+------------+
| 24 | 8B |
+-----------------+------------+
Conections ULN2803A - Motors:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+------------+---------------------+
| ULN2803A | Motors |
+============+=====================+
| 1B | Motor\_1 Coil\_A1 |
+------------+---------------------+
| 2B | Motor\_1 Coil\_A2 |
+------------+---------------------+
| 3B | Motor\_1 Coil\_B1 |
+------------+---------------------+
| 4B | Motor\_1 Coil\_B2 |
+------------+---------------------+
| 5B | Motor\_2 Coil\_A1 |
+------------+---------------------+
| 6B | Motor\_2 Coil\_A2 |
+------------+---------------------+
| 7B | Motor\_2 Coil\_B1 |
+------------+---------------------+
| 8B | Motor\_2 Coil\_B2 |
+------------+---------------------+
In this case, two motors were attached to the ULN2803A.
Usage
-----
class RPiStepper
~~~~~~~~~~~~~~~~
This class allows the user to control a 6 pin stepper motor using 4 GPIO
pins of a RPi.
Software uses BCM mode for pin indexing.
This class is best used with the 'with' statement to properly handle the
cleanup of the GPIOs.
self.steps is a property of this class that will get the number of steps
taken from the initial position or set to a specific step, similar to
self.move.
In order to save power, it's advised to call self.release() when the
motor is idle.
Arguments are a list with the 4 pins (Coil\_A1, Coil\_A2, Coil\_B1,
Coil\_B2), the delay between steps (default = 20ms) and verbose to
display reports on the motor movements, the last two are optional. e.g:
.. code:: python
import RPistepper as stp
M1_pins = [17, 27, 10, 9]
with stp.RPiStepper(M1_pins) as M1:
for i in range(10): # moves 20 steps,release and wait
print M1
M1.move(20)
M1.release()
raw_input('enter to execute next step')
If the class is instantiated normally, use the method ``cleanup`` prior
to closing the application to close the GPIO resources. Also, if it's
important to go back to the initial position when finishing the routine,
use the method ``reset``.
.. code:: python
import RPistepper as stp
M1_pins = [17, 27, 10, 9]
M1 = stp.RPiStepper(M1_pins)
for i in range(10): # moves 20 steps,release and wait
print M1
M1.move(20)
M1.release()
raw_input('enter to execute next step')
M1.reset()
M1.cleanup()
Methods
^^^^^^^
Currently there are four implemented methods:
.. code:: python
def move(self, steps):
'''
Moves the motor 'steps' steps. Negative steps moves the motor backwards
'''
.. code:: python
def release(self):
'''
Sets all pins low. Power saving mode
'''
.. code:: python
def reset(self):
'''
Returns the motor to it's initial position
'''
.. code:: python
def cleanup(self):
'''
Cleans the GPIO resources
'''
The main method is ``move``, which moves the motor the desired number of
steps
steps property
^^^^^^^^^^^^^^
It's possible to check the motor position or manually set the desired
step using the ``steps`` property:
.. code:: python
import RPistepper as stp
M1_pins = [17, 27, 10, 9]
with stp.RPiStepper(M1_pins) as M1:
for i in range(10): # moves 20 steps,release and wait
print M1.steps
M1.steps = 20*i
M1.release()
raw_input('enter to execute next step')
M1.reset()
Attributes
^^^^^^^^^^
This class haves the following attributes:
+-----------------+------------------------------------------------+
| Attribute | Data |
+=================+================================================+
| DELAY | Time between steps |
+-----------------+------------------------------------------------+
| VERBOSE | Display motor data on screen |
+-----------------+------------------------------------------------+
| PINS | GPIOs used by the instance |
+-----------------+------------------------------------------------+
| actual\_state | A list with the status of the coils (on/off) |
+-----------------+------------------------------------------------+
functions
~~~~~~~~~
These two functions executes pre determined movements and requires two
stepper motor objects:
.. code:: python
def zig_zag(motor1, motor2, amp1, amp2, delay=None):
'''
Executes a zig-zag movement with two RPistepper objects.
Arguments are: motor1 and motor2 objects and amp1, amp2, the amplitude
of movement, a tuple (step, rep) representing the number of steps per
iteration and the number of iterations of the following algorithm:
Repeat rep1 times:
1. Moves motor 2 step2*rep2 steps forward
2. Moves motor 1 step1 steps forward
3. Moves motor 2 step2*rep2 steps backwards
4. Moves motor 1 step1 steps forward
Reset to initial state
Release the motors
It's possible to change the delay between steps with the 'delay' argument
'''
.. code:: python
def square_spiral(motor1, motor2, amplitude, delay=None):
'''
Executes a square spiral movement with two RPistepper objects.
Arguments are: motor1 and motor2 objects and the amplitude of movement,
a tuple (step, rep) representing the number of steps per iteration and
the number of iterations of the following algorithm:
for i in range(rep):
1. Moves motor 2 to position i
2. Moves motor 1 to position i
3. Moves motor 1 to position -i
4. Moves motor 2 to position -i
Reset to initial state
Release the motors
It's possible to change the delay between steps with the 'delay' argument
'''
