Moved 2's complement calculation to threshold setters

Threshold properties changed to 12-bit signed integers and conversion to unsigned 16-bit numbers moved to threshold setter functions.

Author: RoaCode

adafruit_ads1x15/ads1x15.py

@@ -96,8 +96,8 @@ def __init__(
  data_rate: Optional[int] = None,
  mode: int = Mode.SINGLE,
  comparator_queue_length: int = 0,
- comparator_low_threshold: int = 0x8000,
- comparator_high_threshold: int = 0x7FF0,
+ comparator_low_threshold: int = -2048,
+ comparator_high_threshold: int = 2047,
  address: int = _ADS1X15_DEFAULT_ADDRESS,
  ):
  # pylint: disable=too-many-arguments
@@ -187,17 +187,24 @@ def comparator_low_threshold(self) -> int:
 
  @comparator_low_threshold.setter
  def comparator_low_threshold(self, comparator_low_threshold: int) -> None:
- """Sets 12-bit threshold in 16-bit register in unsigned format."""
- if comparator_low_threshold < 0 or comparator_low_threshold > 65535:
+ """Sets Comparator low threshold value"""
+ if comparator_low_threshold < -2048 or comparator_low_threshold > 2047:
  raise ValueError(
- "Comparator Low Threshold must be unsigned 16-bit integer between 0 and 65535"
+ "Comparator Low Threshold must be an integer between -2048 and 2047"
  )
  self._comparator_low_threshold = comparator_low_threshold
 
+ """Convert integer value to 12-bit twos complement and bit shift"""
+ if comparator_low_threshold < 0:
+ tempval = 4096 + comparator_low_threshold
+ else:
+ tempval = comparator_low_threshold
+ tempval <<= 4
+
  """Write value to chip"""
  self.buf[0] = _ADS1X15_POINTER_LO_THRES
- self.buf[1] = (self._comparator_low_threshold >> 8) & 0xFF
- self.buf[2] = self._comparator_low_threshold & 0xFF
+ self.buf[1] = (tempval >> 8) & 0xFF
+ self.buf[2] = tempval & 0xFF
  with self.i2c_device as i2c:
  i2c.write(self.buf)
 
@@ -208,17 +215,24 @@ def comparator_high_threshold(self) -> int:
 
  @comparator_high_threshold.setter
  def comparator_high_threshold(self, comparator_high_threshold: int) -> None:
- """Sets 12-bit threshold in 16-bit register in unsigned format."""
- if comparator_high_threshold < 0 or comparator_high_threshold > 65535:
+ """Sets Comparator high threshold value"""
+ if comparator_high_threshold < -2048 or comparator_high_threshold > 2047:
  raise ValueError(
- "Comparator High Threshold must be unsigned 16-bit integer between 0 and 65535"
+ "Comparator High Threshold must be an integer between -2048 and 2047"
  )
  self._comparator_high_threshold = comparator_high_threshold
 
+ """Convert integer value to 12-bit twos complement and bit shift"""
+ if comparator_high_threshold < 0:
+ tempval = 4096 + comparator_high_threshold
+ else:
+ tempval = comparator_high_threshold
+ tempval <<= 4
+
  """Write value to chip"""
  self.buf[0] = _ADS1X15_POINTER_HI_THRES
- self.buf[1] = (self._comparator_high_threshold >> 8) & 0xFF
- self.buf[2] = self._comparator_high_threshold & 0xFF
+ self.buf[1] = (tempval >> 8) & 0xFF
+ self.buf[2] = tempval & 0xFF
  with self.i2c_device as i2c:
  i2c.write(self.buf)
 

adafruit_ads1x15/analog_in.py

@@ -66,14 +66,12 @@ def voltage(self) -> float:
  return volts
 
  def convert_to_value(self, volts: float) -> int:
- """Calculates integer for threshold registers from voltage level input"""
- value = round((volts * 32767) / _ADS1X15_PGA_RANGE[self._ads.gain])
- if value < 0:
- value = 65536 + value
+ """Calculates 12-bit integer for threshold registers from voltage level input"""
+ value = round(volts * 2047 / _ADS1X15_PGA_RANGE[self._ads.gain])
  return value
 
  def convert_to_voltage(self, value: int) -> float:
- """Calculates integer for threshold registers from voltage level input"""
+ """Calculates voltage from 16-bit ADC reading"""
  volts = value * _ADS1X15_PGA_RANGE[self._ads.gain] / 32767
  if volts > _ADS1X15_PGA_RANGE[self._ads.gain]:
  volts = _ADS1X15_PGA_RANGE[self._ads.gain] - volts