Source code for adafruit_register.i2c_bits

# The MIT License (MIT)
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# Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
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# pylint: disable=too-few-public-methods
"""
`adafruit_register.i2c_bits`
====================================================

Multi bit registers

* Author(s): Scott Shawcroft
"""

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

[docs]class RWBits: """ Multibit register (less than a full byte) that is readable and writeable. This must be within a byte register. Values are `int` between 0 and 2 ** ``num_bits`` - 1. :param int num_bits: The number of bits in the field. :param int register_address: The register address to read the bit from :param type lowest_bit: The lowest bits index within the byte at ``register_address`` """ def __init__(self, num_bits, register_address, lowest_bit): self.bit_mask = 0 for _ in range(num_bits): self.bit_mask = (self.bit_mask << 1) + 1 self.bit_mask = self.bit_mask << lowest_bit if self.bit_mask >= (1 << 8): raise ValueError() self.buffer = bytearray(2) self.buffer[0] = register_address self.lowest_bit = lowest_bit def __get__(self, obj, objtype=None): with obj.i2c_device as i2c: i2c.write(self.buffer, end=1, stop=False) i2c.readinto(self.buffer, start=1) return (self.buffer[1] & self.bit_mask) >> self.lowest_bit def __set__(self, obj, value): # Shift the value to the appropriate spot and set all bits that aren't # ours to 1 (the negation of the bitmask.) value = (value << self.lowest_bit) | ~self.bit_mask with obj.i2c_device as i2c: i2c.write(self.buffer, end=1, stop=False) i2c.readinto(self.buffer, start=1) # Set all of our bits to 1. self.buffer[1] |= self.bit_mask # Set all 0 bits to 0 by anding together. self.buffer[1] &= value i2c.write(self.buffer)
[docs]class ROBits(RWBits): """ Multibit register (less than a full byte) that is read-only. This must be within a byte register. Values are `int` between 0 and 2 ** ``num_bits`` - 1. :param int num_bits: The number of bits in the field. :param int register_address: The register address to read the bit from :param type lowest_bit: The lowest bits index within the byte at ``register_address`` """ def __set__(self, obj, value): raise AttributeError()