# SPDX-FileCopyrightText: 2018 Carter Nelson for Adafruit Industries
#
# SPDX-License-Identifier: MIT
"""
`analog_in`
==============================
AnalogIn for single-ended and
differential ADC readings.
* Author(s): Carter Nelson, adapted from MCP3xxx original by Brent Rubell
"""
try:
from typing import Optional
from .ads1x15 import ADS1x15
except ImportError:
pass
_ADS1X15_DIFF_CHANNELS = {(0, 1): 0, (0, 3): 1, (1, 3): 2, (2, 3): 3}
_ADS1X15_PGA_RANGE = {2 / 3: 6.144, 1: 4.096, 2: 2.048, 4: 1.024, 8: 0.512, 16: 0.256}
[docs]
class AnalogIn:
"""AnalogIn Mock Implementation for ADC Reads.
:param ADS1x15 ads: The ads object.
:param int positive_pin: Required pin for single-ended.
:param int negative_pin: Optional pin for differential reads.
"""
def __init__(
self, ads: ADS1x15, positive_pin: int, negative_pin: Optional[int] = None
):
self._ads = ads
self._pin_setting = positive_pin
self._negative_pin = negative_pin
self.is_differential = False
if negative_pin is not None:
pins = (self._pin_setting, self._negative_pin)
if pins not in _ADS1X15_DIFF_CHANNELS:
raise ValueError(
"Differential channels must be one of: {}".format(
list(_ADS1X15_DIFF_CHANNELS.keys())
)
)
self._pin_setting = _ADS1X15_DIFF_CHANNELS[pins]
self.is_differential = True
@property
def value(self) -> int:
"""Returns the value of an ADC pin as an integer."""
return self._ads.read(
self._pin_setting, is_differential=self.is_differential
) << (16 - self._ads.bits)
@property
def voltage(self) -> float:
"""Returns the voltage from the ADC pin as a floating point value."""
volts = self.value * _ADS1X15_PGA_RANGE[self._ads.gain] / 32767
return volts