#----------------------------------------------------------------------------
# Copyright (c) FIRST 2008-2012. All Rights Reserved.
# Open Source Software - may be modified and shared by FRC teams. The code
# must be accompanied by the FIRST BSD license file in the root directory of
# the project.
#----------------------------------------------------------------------------
import weakref
import hal
from .digitalsource import DigitalSource
from .sensorbase import SensorBase
__all__ = ["DigitalOutput"]
def _freePWMGenerator(pwmGenerator):
# Disable the output by routing to a dead bit.
hal.setPWMOutputChannel(pwmGenerator, SensorBase.kDigitalChannels)
hal.freePWM(pwmGenerator)
[docs]class DigitalOutput(DigitalSource):
"""Writes to a digital output
Other devices that are implemented elsewhere will automatically allocate
digital inputs and outputs as required.
"""
def __init__(self, channel):
"""Create an instance of a digital output.
:param channel: the DIO channel for the digital output. 0-9 are on-board, 10-25 are on the MXP
"""
super().__init__(channel, False)
self._pwmGenerator = None
self._pwmGenerator_finalizer = None
hal.HALReport(hal.HALUsageReporting.kResourceType_DigitalOutput,
channel)
@property
[docs] def pwmGenerator(self):
if self._pwmGenerator_finalizer is None:
return None
if not self._pwmGenerator_finalizer.alive:
return None
return self._pwmGenerator
[docs] def free(self):
"""Free the resources associated with a digital output."""
# finalize the pwm only if we have allocated it
if self.pwmGenerator is not None:
self._pwmGenerator_finalizer()
super().free()
[docs] def set(self, value):
"""Set the value of a digital output.
:param value: True is on, off is False
:type value: bool
"""
if self.port is None:
raise ValueError("operation on freed port")
hal.setDIO(self.port, 1 if value else 0)
[docs] def getChannel(self):
""":returns: The GPIO channel number that this object represents.
"""
return self.channel
[docs] def pulse(self, channel, pulseLength):
"""Generate a single pulse. Write a pulse to the specified digital
output channel. There can only be a single pulse going at any time.
:param channel: The channel to pulse.
:param pulseLength: The length of the pulse.
:type pulseLength: float
"""
if self.port is None:
raise ValueError("operation on freed port")
hal.pulse(self.port, pulseLength)
[docs] def isPulsing(self):
"""Determine if the pulse is still going. Determine if a previously
started pulse is still going.
:returns: True if pulsing
:rtype: bool
"""
if self.port is None:
raise ValueError("operation on freed port")
return hal.isPulsing(self.port)
[docs] def setPWMRate(self, rate):
"""Change the PWM frequency of the PWM output on a Digital Output line.
The valid range is from 0.6 Hz to 19 kHz. The frequency resolution is
logarithmic.
There is only one PWM frequency for all channnels.
:param rate: The frequency to output all digital output PWM signals.
:type rate: float
"""
hal.setPWMRate(rate)
[docs] def enablePWM(self, initialDutyCycle):
"""Enable a PWM Output on this line.
Allocate one of the 6 DO PWM generator resources.
Supply the initial duty-cycle to output so as to avoid a glitch when
first starting.
The resolution of the duty cycle is 8-bit for low frequencies (1kHz or
less) but is reduced the higher the frequency of the PWM signal is.
:param initialDutyCycle: The duty-cycle to start generating. [0..1]
:type initialDutyCycle: float
"""
if self.pwmGenerator is not None:
return
self._pwmGenerator = hal.allocatePWM()
hal.setPWMDutyCycle(self._pwmGenerator, initialDutyCycle)
hal.setPWMOutputChannel(self._pwmGenerator, self.channel)
self._pwmGenerator_finalizer = \
weakref.finalize(self, _freePWMGenerator, self._pwmGenerator)
[docs] def disablePWM(self):
"""Change this line from a PWM output back to a static Digital Output
line.
Free up one of the 6 DO PWM generator resources that were in use.
"""
if self.pwmGenerator is None:
return
self._pwmGenerator_finalizer()
[docs] def updateDutyCycle(self, dutyCycle):
"""Change the duty-cycle that is being generated on the line.
The resolution of the duty cycle is 8-bit for low frequencies (1kHz or
less) but is reduced the higher the frequency of the PWM signal is.
:param dutyCycle: The duty-cycle to change to. [0..1]
:type dutyCycle: float
"""
if self.pwmGenerator is None:
return
hal.setPWMDutyCycle(self.pwmGenerator, dutyCycle)
# Live Window code, only does anything if live window is activated.
def getSmartDashboardType(self):
return "Digital Output"
def updateTable(self):
# TODO: Put current value.
pass
def valueChanged(self, itable, key, value, bln):
self.set(True if value else False)