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Support 8-bit expanders like the PCF8574 👾 #4

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Support 8-bit expanders like the PCF8574 👾 #4

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20 changes: 12 additions & 8 deletions adafruit_pcf8575.py
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Original file line number Diff line number Diff line change
Expand Up @@ -48,39 +48,43 @@ class PCF8575:

:param ~busio.I2C i2c_bus: The I2C bus the PCF8575 is connected to.
:param int address: The I2C device address. Default is :const:`0x20`
:param int gpios: The number of GPIO pins (8 or 16). Default is 16.
"""

def __init__(
self, i2c_bus: busio.I2C, address: int = PCF8575_I2CADDR_DEFAULT
self, i2c_bus: busio.I2C, address: int = PCF8575_I2CADDR_DEFAULT,
gpios: int = 16
) -> None:
self.i2c_device = I2CDevice(i2c_bus, address)
self._gpios = gpios
assert self._gpios == 8 or self._gpios == 16
self._writebuf = bytearray([0, 0])
self._readbuf = bytearray([0, 0])

def get_pin(self, pin: int) -> "DigitalInOut":
"""Convenience function to create an instance of the DigitalInOut class
pointing at the specified pin of this PCF8575 device.

:param int pin: pin to use for digital IO, 0 to 15
:param int pin: pin to use for digital IO
"""
assert 0 <= pin <= 15
assert 0 <= pin <= self._gpios
return DigitalInOut(pin, self)

def write_gpio(self, val: int) -> None:
"""Write a full 16-bit value to the GPIO register
"""Write a full value to the GPIO register

:param int val: The value to write to the register
"""

self._writebuf[0] = val & 0xFF
self._writebuf[1] = (val >> 8) & 0xFF
with self.i2c_device as i2c:
i2c.write(self._writebuf)
i2c.write(self._writebuf, end=self._gpios >> 3)

def read_gpio(self) -> int:
"""Read the full 16-bits of data from the GPIO register"""
"""Read the full data from the GPIO register"""
with self.i2c_device as i2c:
i2c.readinto(self._readbuf)
i2c.readinto(self._readbuf, end=self._gpios >> 3)
return self._readbuf[0] | (self._readbuf[1] << 8)

def write_pin(self, pin: int, val: bool) -> None:
Expand Down Expand Up @@ -128,7 +132,7 @@ class DigitalInOut:
"""

def __init__(self, pin_number: int, pcf: PCF8575) -> None:
"""Specify the pin number of the PCF8575 0..15, and instance.
"""Specify the pin number of the PCF8575, and instance.

:param int pin_number: The pin number
:param PCF8575 pfc: The associated PCF8575 instance
Expand Down