Source code for adafruit_ds2413

# SPDX-FileCopyrightText: 2017 Carter Nelson for Adafruit Industries
#
# SPDX-License-Identifier: MIT
# pylint: disable=C0103

"""
`adafruit_ds2413`
====================================================

 CircuitPython driver for the DS2413 one wire 2 channel GPIO breakout.

* Author(s): Carter Nelson
"""

__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_DS2413.git"

from micropython import const
from adafruit_onewire.device import OneWireDevice

_DS2413_ACCESS_READ = b"\xF5"
_DS2413_ACCESS_WRITE = b"\x5A"
_DS2413_ACK_SUCCESS = b"\xAA"
_DS2413_ACK_ERROR = b"\xFF"
INPUT = const(0)
OUTPUT = const(1)


[docs]class DS2413Pin: """Class which provides interface to single DS2413 GPIO pin.""" def __init__(self, number, host, direction=OUTPUT): if number not in (0, 1): raise ValueError("Incorrect pin number.") self._number = number self._host = host self._mask = 1 << (number * 2) self._direction = None # create it, and then... self.direction = direction # set it through setter @property def direction(self): """The direction of the pin, either INPUT or OUTPUT.""" return self._direction @direction.setter def direction(self, direction): if direction not in (INPUT, OUTPUT): raise ValueError("Incorrect direction setting.") self._direction = OUTPUT self.value = False self._direction = direction @property def value(self): """The pin state if configured as INPUT. The output latch state if configured as OUTPUT. True is HIGH/ON, False is LOW/OFF.""" # return Pin State if configured for INPUT # return Latch State if configured for OUTPUT # NOTE: logic is re-inverted to make it more normally return not self._host.pio_state & (self._mask << self._direction) @value.setter def value(self, state): # This only makes sense if the pin is configured for OUTPUT. if self._direction == INPUT: raise RuntimeError("Can't set value when pin is set to input.") # We jump through some hoops in order to only set/clear the bit # for the channel associated with this pin object. current = self._host.pio_state # PIOB Output Latch PIOA Output Latch new = (current >> 2 & 0x02) | (current >> 1 & 0x01) # To switch the output transistor on, the corresponding bit value is 0. # To switch the output transistor off (non-conducting) the bit must be 1. if state: # clear it (transistor = ON) new &= ~(1 << self._number) else: # set it (transistor = OFF) new |= 1 << self._number self._host.pio_state = new
[docs]class DS2413: """Class which provides interface to DS2413 GPIO breakout.""" def __init__(self, bus, address): if address.family_code == 0x3A: self._address = address self._device = OneWireDevice(bus, address) self._buf = bytearray(3) self._IOA = None self._IOB = None else: raise RuntimeError("Incorrect family code in device address.") @property def IOA(self): """The pin object for channel A.""" if self._IOA is None: self._IOA = DS2413Pin(0, self) return self._IOA @property def IOB(self): """The pin object for channel B.""" if self._IOB is None: self._IOB = DS2413Pin(1, self) return self._IOB @property def pio_state(self): """The state of both PIO channels.""" return self._read_status() @pio_state.setter def pio_state(self, value): return self._write_latches(value) def _read_status(self): with self._device as dev: dev.write(_DS2413_ACCESS_READ) dev.readinto(self._buf, end=1) return self._buf[0] def _write_latches(self, value): # top six bits must be 1 value |= 0xFC self._buf[0] = value self._buf[1] = ~value & 0xFF with self._device as dev: dev.write(_DS2413_ACCESS_WRITE) dev.write(self._buf, end=2) dev.readinto(self._buf, end=1) if not self._buf[0] == ord(_DS2413_ACK_SUCCESS): raise RuntimeError("ACK failure.")