changed weight to a property, handle pin toggling better, perform unit conversion within the property

Author: brentru

adafruit_dymoscale.py

@@ -63,28 +63,35 @@ def __init__(self, data_pin, units_pin, timeout=1.0):
  self.units_pin = DigitalInOut(units_pin)
  self.units_pin.switch_to_output()
  self.dymo = PulseIn(data_pin, maxlen=96, idle_state=True)
- # units we're measuring
- self.units = None
- # is the measurement stable?
  self.stable = None
- # the weight of what we're measuring
- self.weight = None
+ self.units = None
+
+ @property
+ def weight(self):
+ """Weight in grams"""
+ weight = self.get_scale_data()
+ #print('debugg: ', weight)
+ if self.units == OUNCES:
+ weight = weight * 28.35
+ self.units = 'oz'
+ elif self.units == GRAMS:
+ self.units = 'g'
+ return weight
 
- def toggle_unit_button(self, switch_unit=False):
+ def toggle_unit_button(self, switch_units=False):
  """Toggles the unit button on the dymo.
- :param bool switch_unit: Simulates pressing the unit button.
+ :param bool switch_units: Simulates pressing the units button.
  """
- if switch_unit: # press the toggle button once
- self.units_pin.value = 1
- time.sleep(2)
- self.units_pin.value = 0
- time.sleep(2)
+ toggle_times = 0
+ if switch_units: # press the button once
+ toggle_amt = 2
  else: # toggle and preserve current unit state
- for toggle in range(2):
- self.units_pin.value = 1
- time.sleep(2)
- self.units_pin.value = 0
- time.sleep(2)
+ toggle_amt = 4
+ while toggle_times < toggle_amt:
+ self.units_pin.value ^= 1
+ print('toggle: ', self.units_pin.value)
+ time.sleep(2)
+ toggle_times+=1
 
  def get_scale_data(self):
  """Read a pulse of SPI data on a pin that corresponds to DYMO scale
@@ -125,18 +132,17 @@ def get_scale_data(self):
  if data_bytes[8] != 0x1C or data_bytes[9] != 0 or data_bytes[10] \
  or data_bytes[11] != 0:
  raise RuntimeError("Bad data capture")
+
  # parse out the data_bytes
  self.stable = data_bytes[2] & 0x4
  self.units = data_bytes[3]
- self.weight = data_bytes[5] + (data_bytes[6] << 8)
+ weight = data_bytes[5] + (data_bytes[6] << 8)
  if data_bytes[2] & 0x1:
- self.weight *= -1
+ weight *= -1
  print('Tare - press the tare button to reset the scale to zero.')
  if self.units == OUNCES:
  if data_bytes[4] & 0x80:
  data_bytes[4] -= 0x100
  print('Tare - press the tare button to reset the scale to zero.')
- self.weight *= 10 ** data_bytes[4]
- self.units = "oz"
- elif self.units == GRAMS:
- self.units = "g"
+ weight *= 10 ** data_bytes[4]
+ return weight