def pwmEnable(pwm_pin):
""" Ensures given PWM output is reserved for userspace use and
sets proper pinmux. Sets frequency to default value if output
not already reserved. """
assert (pwm_pin in PWM_PINS), "*Invalid PWM pin: '%s'" % pwm_pin
# Set pinmux mode:
pinmux.pinMux(PWM_PINS[pwm_pin][0], PWM_PINS[pwm_pin][1])
if ('sysfs' not in pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_REQUEST])):
# Reserve use of output:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_REQUEST], '1')
delay(1) # Give it some time to take effect
# Make sure output is disabled, so it won't start outputing a
# signal until analogWrite() is called:
if (pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE]) == '1\n'):
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE], '0')
# Duty cyle must be set to 0 before changing frequency:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY], '0')
# Set frequency to default:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_FREQ], str(PWM_DEFAULT_FREQ))
def pwmEnable(pwm_pin):
""" Ensures given PWM output is reserved for userspace use and
sets proper pinmux. Sets frequency to default value if output
not already reserved. """
assert (pwm_pin in PWM_PINS), "*Invalid PWM pin: '%s'" % pwm_pin
# Set pinmux mode:
pinmux.pinMux(PWM_PINS[pwm_pin][0], PWM_PINS[pwm_pin][1])
if ('sysfs' not in pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_REQUEST])):
# Reserve use of output:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_REQUEST], '1')
delay(1) # Give it some time to take effect
# Make sure output is disabled, so it won't start outputing a
# signal until analogWrite() is called:
if (pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE]) == '1\n'):
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE], '0')
# Duty cyle must be set to 0 before changing frequency:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY], '0')
# Set frequency to default:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_FREQ],
str(PWM_DEFAULT_FREQ))
def pwmDisable(pwm_pin):
""" Disables PWM output on given pin. """
assert (pwm_pin in PWM_PINS), "*Invalid PWM pin: '%s'" % pwm_pin
# Disable PWM output:
if (pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE]) == '1\n'):
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE], '0')
# Relinquish userspace control:
if ('sysfs' in pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_REQUEST])):
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_REQUEST], '0')
def pwmDisable(pwm_pin):
""" Disables PWM output on given pin. """
assert (pwm_pin in PWM_PINS), "*Invalid PWM pin: '%s'" % pwm_pin
# Disable PWM output:
if (pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE]) == '1\n'):
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE], '0')
# Relinquish userspace control:
if ('sysfs' in pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_REQUEST])):
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_REQUEST], '0')
def analogWrite(pwm_pin, value, resolution=RES_8BIT):
""" Sets the duty cycle of the given PWM output using the
given resolution. """
# Make sure the pin is configured:
pwmEnable(pwm_pin)
try:
assert resolution > 0, "*PWM resolution must be greater than 0"
if (value < 0): value = 0
if (value >= resolution): value = resolution - 1
freq = int(pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_FREQ]))
period_ns = (1e9 / freq)
# Todo: round values properly!:
duty_ns = int(value * (period_ns / resolution))
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY], str(duty_ns))
# Enable output:
if (pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE]) == '0\n'):
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE], '1')
except IOError:
print "*PWM pin '%s' reserved by another process!" % pwm_pin
def analogWrite(pwm_pin, value, resolution=RES_8BIT):
""" Sets the duty cycle of the given PWM output using the
given resolution. """
# Make sure the pin is configured:
pwmEnable(pwm_pin)
try:
assert resolution > 0, "*PWM resolution must be greater than 0"
if (value < 0): value = 0
if (value >= resolution): value = resolution-1
freq = int(pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_FREQ]))
period_ns = (1e9/freq)
# Todo: round values properly!:
duty_ns = int(value * (period_ns/resolution))
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY], str(duty_ns))
# Enable output:
if (pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE]) == '0\n'):
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_ENABLE], '1')
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:
old_duty_ns = int(kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY]))
old_period_ns = 1e9 / int(kernelFileIO(PWM_FILES[pwm_pin][PWM_FREQ]))
duty_percent = old_duty_ns / old_period_ns
new_period_ns = 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:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY], '0')
# Set new frequency:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_FREQ], str(freq_hz))
# Set the duty cycle:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][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:
old_duty_ns = int(kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY]))
old_period_ns = 1e9/int(kernelFileIO(PWM_FILES[pwm_pin][PWM_FREQ]))
duty_percent = old_duty_ns / old_period_ns
new_period_ns = 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:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY], '0')
# Set new frequency:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_FREQ], str(freq_hz))
# Set the duty cycle:
pinmux.kernelFileIO(PWM_FILES[pwm_pin][PWM_DUTY], str(new_duty_ns))
except IOError:
print "*PWM pin '%s' reserved by another process!" % pwm_pin
