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raise explanatory exception when trying to set channel frequency #14

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Merged
merged 1 commit into from
Jul 31, 2018
Merged

raise explanatory exception when trying to set channel frequency #14

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12 changes: 9 additions & 3 deletions adafruit_pca9685.py
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Original file line number Diff line number Diff line change
Expand Up @@ -65,9 +65,15 @@ def __init__(self, pca, index):

@property
def frequency(self):
"""The overall PWM frequency in herz."""
"""The overall PWM frequency in Hertz (read-only).
A PWMChannel's frequency cannot be set individually.
All channels share a common frequency, set by PCA9685.frequency."""
return self._pca.frequency

@frequency.setter
def frequency(self, _):
raise NotImplementedError("frequency cannot be set on individual channels")

@property
def duty_cycle(self):
"""16 bit value that dictates how much of one cycle is high (1) versus low (0). 0xffff will
Expand Down Expand Up @@ -114,7 +120,7 @@ class PCA9685:

:param ~busio.I2C i2c_bus: The I2C bus which the PCA9685 is connected to.
:param int address: The I2C address of the PCA9685.
:param int reference_clock_speed: The frequency of the internal reference clock in Herz.
:param int reference_clock_speed: The frequency of the internal reference clock in Hertz.
"""
# Registers:
mode1_reg = UnaryStruct(0x00, '<B')
Expand All @@ -135,7 +141,7 @@ def reset(self):

@property
def frequency(self):
"""The overall PWM frequency in herz."""
"""The overall PWM frequency in Hertz."""
return self.reference_clock_speed / 4096 / self.prescale_reg

@frequency.setter
Expand Down