# The MIT License (MIT)
#
# Copyright (c) 2017 Carter Nelson for Adafruit Industries
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
"""
`adafruit_ads1x15.single_ended`
====================================================
Single-ended driver for ADS1015/1115 ADCs.
* Author(s): Carter Nelson
"""
__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_ADS1x15.git"
from .adafruit_ads1x15 import ADS1x15
from .adafruit_ads1x15 import ADS1X15_CONFIG_MODE_SINGLE, ADS1X15_CONFIG_MODE_CONTINUOUS
from .adafruit_ads1x15 import ADS1X15_PGA_RANGE, ADS1015_CONFIG_DR, ADS1115_CONFIG_DR
# pylint: disable=abstract-method
[docs]class ADS1x15_SingleEnded(ADS1x15):
"""Base functionality for ADS1x15 analog to digital converters operating
in single ended mode."""
def __getitem__(self, key):
return self._channels[key]
[docs] def read_adc(self, channel, gain=1, data_rate=None):
"""Read a single ADC channel and return the ADC value as a signed integer
result. Channel must be a value within 0-3.
"""
if not 0 <= channel <= 3:
raise ValueError('Channel must be a value within 0-3!')
# Perform a single shot read and set the mux value to the channel plus
# the highest bit (bit 3) set.
return self._read(channel + 0x04, gain, data_rate, ADS1X15_CONFIG_MODE_SINGLE)
[docs] def read_volts(self, channel, gain=1, data_rate=None):
"""Read a single ADC channel and return the voltage value as a floating point
result. Channel must be a value within 0-3.
"""
if not 0 <= channel <= 3:
raise ValueError('Channel must be a value within 0-3!')
raw = self.read_adc(channel, gain, data_rate)
volts = raw * (ADS1X15_PGA_RANGE[gain] / (2**(self.bits-1) - 1))
return volts
[docs] def start_adc(self, channel, gain=1, data_rate=None):
"""Start continuous ADC conversions on the specified channel (0-3). Will
return an initial conversion result, then call the get_last_result()
function to read the most recent conversion result. Call stop_adc() to
stop conversions.
"""
if not 0 <= channel <= 3:
raise ValueError('Channel must be a value within 0-3!')
# Start continuous reads and set the mux value to the channel plus
# the highest bit (bit 3) set.
return self._read(channel + 0x04, gain, data_rate, ADS1X15_CONFIG_MODE_CONTINUOUS)
# pylint: enable=abstract-method
[docs]class ADS1015(ADS1x15_SingleEnded):
"""ADS1015 12-bit single ended analog to digital converter instance."""
def __init__(self, *args, **kwargs):
super(ADS1015, self).__init__(*args, **kwargs)
self.bits = 12
def _data_rate_default(self):
# Default from datasheet page 19, config register DR bit default.
return 1600
def _data_rate_config(self, data_rate):
if data_rate not in ADS1015_CONFIG_DR:
raise ValueError('Data rate must be one of: 128, 250, 490, 920, 1600, 2400, 3300')
return ADS1015_CONFIG_DR[data_rate]
def _conversion_value(self, low, high):
# Convert to 12-bit signed value.
value = ((high & 0xFF) << 4) | ((low & 0xFF) >> 4)
# Check for sign bit and turn into a negative value if set.
if value & 0x800 != 0:
value -= 1 << 12
return value
def _read_channel(self, channel):
return self.read_adc(channel)
def _read_channel_volts(self, channel):
return self.read_volts(channel)
[docs]class ADS1115(ADS1x15_SingleEnded):
"""ADS1115 16-bit single ended analog to digital converter instance."""
def __init__(self, *args, **kwargs):
super(ADS1115, self).__init__(*args, **kwargs)
self.bits = 16
def _data_rate_default(self):
# Default from datasheet page 16, config register DR bit default.
return 128
def _data_rate_config(self, data_rate):
if data_rate not in ADS1115_CONFIG_DR:
raise ValueError('Data rate must be one of: 8, 16, 32, 64, 128, 250, 475, 860')
return ADS1115_CONFIG_DR[data_rate]
def _conversion_value(self, low, high):
# Convert to 16-bit signed value.
value = ((high & 0xFF) << 8) | (low & 0xFF)
# Check for sign bit and turn into a negative value if set.
if value & 0x8000 != 0:
value -= 1 << 16
return value
def _read_channel(self, channel):
return self.read_adc(channel)
def _read_channel_volts(self, channel):
return self.read_volts(channel)