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# Copyright (c) 2014 Adafruit Industries
# Author: Tony DiCola
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
import Adafruit_GPIO.Platform as Platform
class RPi_PWM_Adapter(object):
"""PWM implementation for the Raspberry Pi using the RPi.GPIO PWM library."""
def __init__(self, rpi_gpio, mode=None):
self.rpi_gpio = rpi_gpio
# Suppress warnings about GPIO in use.
rpi_gpio.setwarnings(False)
# Set board or BCM pin numbering.
if mode == rpi_gpio.BOARD or mode == rpi_gpio.BCM:
rpi_gpio.setmode(mode)
elif mode is not None:
raise ValueError('Unexpected value for mode. Must be BOARD or BCM.')
else:
# Default to BCM numbering if not told otherwise.
rpi_gpio.setmode(rpi_gpio.BCM)
# Store reference to each created PWM instance.
self.pwm = {}
def start(self, pin, dutycycle, frequency_hz=2000):
"""Enable PWM output on specified pin. Set to intiial percent duty cycle
value (0.0 to 100.0) and frequency (in Hz).
"""
if dutycycle < 0.0 or dutycycle > 100.0:
raise ValueError('Invalid duty cycle value, must be between 0.0 to 100.0 (inclusive).')
# Make pin an output.
self.rpi_gpio.setup(pin, self.rpi_gpio.OUT)
# Create PWM instance and save a reference for later access.
self.pwm[pin] = self.rpi_gpio.PWM(pin, frequency_hz)
# Start the PWM at the specified duty cycle.
self.pwm[pin].start(dutycycle)
def set_duty_cycle(self, pin, dutycycle):
"""Set percent duty cycle of PWM output on specified pin. Duty cycle must
be a value 0.0 to 100.0 (inclusive).
"""
if dutycycle < 0.0 or dutycycle > 100.0:
raise ValueError('Invalid duty cycle value, must be between 0.0 to 100.0 (inclusive).')
if pin not in self.pwm:
raise ValueError('Pin {0} is not configured as a PWM. Make sure to first call start for the pin.'.format(pin))
self.pwm[pin].ChangeDutyCycle(dutycycle)
def set_frequency(self, pin, frequency_hz):
"""Set frequency (in Hz) of PWM output on specified pin."""
if pin not in self.pwm:
raise ValueError('Pin {0} is not configured as a PWM. Make sure to first call start for the pin.'.format(pin))
self.pwm[pin].ChangeFrequency(frequency_hz)
def stop(self, pin):
"""Stop PWM output on specified pin."""
if pin not in self.pwm:
raise ValueError('Pin {0} is not configured as a PWM. Make sure to first call start for the pin.'.format(pin))
self.pwm[pin].stop()
del self.pwm[pin]
class BBIO_PWM_Adapter(object):
"""PWM implementation for the BeagleBone Black using the Adafruit_BBIO.PWM
library.
"""
def __init__(self, bbio_pwm):
self.bbio_pwm = bbio_pwm
def start(self, pin, dutycycle, frequency_hz=2000):
"""Enable PWM output on specified pin. Set to intiial percent duty cycle
value (0.0 to 100.0) and frequency (in Hz).
"""
if dutycycle < 0.0 or dutycycle > 100.0:
raise ValueError('Invalid duty cycle value, must be between 0.0 to 100.0 (inclusive).')
self.bbio_pwm.start(pin, dutycycle, frequency_hz)
def set_duty_cycle(self, pin, dutycycle):
"""Set percent duty cycle of PWM output on specified pin. Duty cycle must
be a value 0.0 to 100.0 (inclusive).
"""
if dutycycle < 0.0 or dutycycle > 100.0:
raise ValueError('Invalid duty cycle value, must be between 0.0 to 100.0 (inclusive).')
self.bbio_pwm.set_duty_cycle(pin, dutycycle)
def set_frequency(self, pin, frequency_hz):
"""Set frequency (in Hz) of PWM output on specified pin."""
self.bbio_pwm.set_frequency(pin, frequency_hz)
def stop(self, pin):
"""Stop PWM output on specified pin."""
self.bbio_pwm.stop(pin)
def get_platform_pwm(**keywords):
"""Attempt to return a PWM instance for the platform which the code is being
executed on. Currently supports only the Raspberry Pi using the RPi.GPIO
library and Beaglebone Black using the Adafruit_BBIO library. Will throw an
exception if a PWM instance can't be created for the current platform. The
returned PWM object has the same interface as the RPi_PWM_Adapter and
BBIO_PWM_Adapter classes.
"""
plat = Platform.platform_detect()
if plat == Platform.RASPBERRY_PI:
import RPi.GPIO
return RPi_PWM_Adapter(RPi.GPIO, **keywords)
elif plat == Platform.BEAGLEBONE_BLACK:
import Adafruit_BBIO.PWM
return BBIO_PWM_Adapter(Adafruit_BBIO.PWM, **keywords)
elif plat == Platform.UNKNOWN:
raise RuntimeError('Could not determine platform.')
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