def analogWrite(pwm_pin, value, resolution=RES_8BIT, polarity=0):
""" Sets the duty cycle of the given PWM output using the
given resolution. If polarity=0 this will set the width of
the positive pulse, otherwise it will set the width of the
negative pulse. """
# Make sure the pin is configured:
pwmEnable(pwm_pin)
pin_config = PWM_PINS[pwm_pin]
helper_path = pin_config[1]
try:
assert resolution > 0, "*PWM resolution must be greater than 0"
if (value < 0): value = 0
if (value >= resolution): value = resolution-1
period_ns = int(sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_PERIOD)))
# Todo: round values properly!:
duty_ns = int(value * (period_ns/resolution))
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY), str(duty_ns))
if polarity == 0:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_POLARITY), '0')
else:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_POLARITY), '1')
# Enable output:
if (sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN)) == '0\n'):
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN), '1')
except IOError:
print "*PWM pin '%s' reserved by another process!" % pwm_pin
def pwmDisable(pwm_pin):
""" Disables PWM output on given pin. """
pin_config = PWM_PINS[pwm_pin]
assert (pin_config), "*Invalid PWM pin: '%s'" % pwm_pin
helper_path = pin_config[1]
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN), '0')
PWM_PINS_ENABLED[pwm_pin] = False
def analogWrite(pwm_pin, value, resolution=RES_8BIT, polarity=0):
""" Sets the duty cycle of the given PWM output using the
given resolution. If polarity=0 this will set the width of
the positive pulse, otherwise it will set the width of the
negative pulse. """
# Make sure the pin is configured:
pwmEnable(pwm_pin)
pin_config = PWM_PINS[pwm_pin]
helper_path = pin_config[1]
try:
assert resolution > 0, "*PWM resolution must be greater than 0"
if (value < 0): value = 0
if (value >= resolution): value = resolution - 1
period_ns = int(
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_PERIOD)))
# Todo: round values properly!:
duty_ns = int(value * (period_ns / resolution))
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY), str(duty_ns))
if polarity == 0:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_POLARITY), '0')
else:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_POLARITY), '1')
# Enable output:
if (sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN)) == '0\n'):
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN), '1')
except IOError:
print "*PWM pin '%s' reserved by another process!" % pwm_pin
def pwmDisable(pwm_pin):
""" Disables PWM output on given pin. """
pin_config = PWM_PINS[pwm_pin]
assert (pin_config), "*Invalid PWM pin: '%s'" % pwm_pin
helper_path = pin_config[1]
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN), '0')
PWM_PINS_ENABLED[pwm_pin] = False
def pwmFrequency(pwm_pin, freq_hz):
""" Sets the frequncy in Hertz of the given PWM output's module. """
assert (pwm_pin in PWM_PINS), "*Invalid PWM pin: '%s'" % pwm_pin
assert freq_hz > 0, "*PWM frequency must be greater than 0"
# Make sure the pin is configured:
pwmEnable(pwm_pin)
# calculate the duty cycle in nanoseconds for the new period:
pin_config = PWM_PINS[pwm_pin]
helper_path = pin_config[1]
old_duty_ns = int(sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY)))
old_period_ns = int(sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_PERIOD)))
duty_percent = old_duty_ns / old_period_ns
new_period_ns = int(1e9/freq_hz)
# Todo: round values properly!:
new_duty_ns = int(duty_percent * new_period_ns)
try:
# Duty cyle must be set to 0 before changing frequency:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY), '0')
# Set new frequency:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_PERIOD), str(new_period_ns))
# Set the duty cycle:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY), str(new_duty_ns))
except IOError:
print "*PWM pin '%s' reserved by another process!" % pwm_pin
def pwmFrequency(pwm_pin, freq_hz):
""" Sets the frequncy in Hertz of the given PWM output's module. """
assert (pwm_pin in PWM_PINS), "*Invalid PWM pin: '%s'" % pwm_pin
assert freq_hz > 0, "*PWM frequency must be greater than 0"
# Make sure the pin is configured:
pwmEnable(pwm_pin)
# calculate the duty cycle in nanoseconds for the new period:
pin_config = PWM_PINS[pwm_pin]
helper_path = pin_config[1]
old_duty_ns = int(sysfs.kernelFilenameIO('%s/%s' %
(helper_path, PWM_DUTY)))
old_period_ns = int(
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_PERIOD)))
duty_percent = old_duty_ns / old_period_ns
new_period_ns = int(1e9 / freq_hz)
# Todo: round values properly!:
new_duty_ns = int(duty_percent * new_period_ns)
try:
# Duty cyle must be set to 0 before changing frequency:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY), '0')
# Set new frequency:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_PERIOD),
str(new_period_ns))
# Set the duty cycle:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY),
str(new_duty_ns))
except IOError:
print "*PWM pin '%s' reserved by another process!" % pwm_pin
def pwmEnable(pwm_pin):
""" Ensures PWM module for the given pin is enabled and its ocp helper
is loaded. """
global PWM_PINS_ENABLED
if PWM_PINS_ENABLED.get(pwm_pin): return
pin_config = PWM_PINS[pwm_pin]
assert (pin_config), "*Invalid PWM pin: '%s'" % pwm_pin
for overlay in pin_config[2]:
cape_manager.load(overlay, auto_unload=False)
delay(250) # Give it some time to take effect
cape_manager.load(pin_config[0], auto_unload=False)
delay(250)
helper_path = pin_config[1]
# Make sure output is disabled, so it won't start outputing a
# signal until analogWrite() is called:
if (sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN)) == '1\n'):
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN), '0')
# Duty cyle must be set to 0 before changing frequency:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY), '0')
# Is this still true??
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_PERIOD),
str(PWM_DEFAULT_PERIOD))
addToCleanup(lambda : pwmDisable(pwm_pin))
PWM_PINS_ENABLED[pwm_pin] = True
def pwmEnable(pwm_pin):
""" Ensures PWM module for the given pin is enabled and its ocp helper
is loaded. """
global PWM_PINS_ENABLED
if PWM_PINS_ENABLED.get(pwm_pin): return
pin_config = PWM_PINS[pwm_pin]
assert (pin_config), "*Invalid PWM pin: '%s'" % pwm_pin
for overlay in pin_config[2]:
cape_manager.load(overlay, auto_unload=False)
delay(250) # Give it some time to take effect
cape_manager.load(pin_config[0], auto_unload=False)
delay(250)
helper_path = pin_config[1]
# Make sure output is disabled, so it won't start outputing a
# signal until analogWrite() is called:
if (sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN)) == '1\n'):
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_RUN), '0')
# Duty cyle must be set to 0 before changing frequency:
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_DUTY), '0')
# Is this still true??
sysfs.kernelFilenameIO('%s/%s' % (helper_path, PWM_PERIOD),
str(PWM_DEFAULT_PERIOD))
addToCleanup(lambda: pwmDisable(pwm_pin))
PWM_PINS_ENABLED[pwm_pin] = True
