185 lines
6.5 KiB
Python
185 lines
6.5 KiB
Python
# SPDX-FileCopyrightText: 2022 Jan Goolsbey for Adafruit Industries
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# SPDX-License-Identifier: MIT
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#
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# clue_scale_code.py
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# 2022-07-29 v1.2.0
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#
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# Clue Scale - Single Channel Version
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# Adafruit NAU7802 Stemma breakout example
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# import clue_scale_calibrator # Uncomment to run calibrator method
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import time
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import board
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from simpleio import map_range
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from adafruit_clue import clue
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from adafruit_display_shapes.circle import Circle
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from adafruit_display_text.label import Label
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from adafruit_bitmap_font import bitmap_font
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import displayio
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from cedargrove_nau7802 import NAU7802
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clue.pixel.brightness = 0.2 # Set NeoPixel brightness
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clue.pixel[0] = clue.YELLOW # Set status indicator to yellow (initializing)
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# Set Scale Defaults
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MAX_GR = 100 # Maximum (full-scale) display range in grams
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DEFAULT_GAIN = 128 # Default gain for internal PGA
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SAMPLE_AVG = 100 # Number of sample values to average
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SCALE_NAME_1 = "COFFEE" # 6 characters maximum
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SCALE_NAME_2 = "SCALE" # 6 characters maximum
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"""Enter the calibration ratio for the individual load cell in-use. The ratio is
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composed of the reference weight in grams divided by the raw reading. For
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example, a raw reading of 215300 for a 100 gram weight results in a calibration
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ratio of 100 / 215300. Use the clue_scale_single_calibrate method to obtain the
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raw value.
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FYI: A US dime coin weighs 2.268 grams or 0.079 ounces."""
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CALIB_RATIO = 100 / 215300 # load cell serial#4540-02
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# Instantiate the Sensor and Display
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nau7802 = NAU7802(board.I2C(), address=0x2A, active_channels=1)
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display = board.DISPLAY
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scale_group = displayio.Group()
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FONT_0 = bitmap_font.load_font("/fonts/Helvetica-Bold-24.bdf")
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FONT_1 = bitmap_font.load_font("/fonts/OpenSans-16.bdf")
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FONT_2 = bitmap_font.load_font("/fonts/OpenSans-9.bdf")
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# Display the Background Bitmap Image
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bkg = displayio.OnDiskBitmap("/clue_scale_bkg.bmp")
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_background = displayio.TileGrid(bkg, pixel_shader=bkg.pixel_shader, x=0, y=0)
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scale_group.append(_background)
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# Define and Display the Text Labels and Graphic Elements
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# Place the project name on either side of the graduated scale
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scale_name_1 = Label(FONT_1, text=SCALE_NAME_1, color=clue.CYAN)
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scale_name_1.anchor_point = (0.5, 0.5)
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scale_name_1.anchored_position = (40, 96)
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scale_group.append(scale_name_1)
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scale_name_2 = Label(FONT_1, text=SCALE_NAME_2, color=clue.CYAN)
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scale_name_2.anchor_point = (0.5, 0.5)
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scale_name_2.anchored_position = (199, 96)
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scale_group.append(scale_name_2)
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# Define the zeroing button graphic
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zero_button_circle = Circle(14, 152, 14, fill=None, outline=clue.RED, stroke=2)
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scale_group.append(zero_button_circle)
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zero_button_label = Label(FONT_1, text="Z", color=clue.RED)
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zero_button_label.x = 8
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zero_button_label.y = 150
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scale_group.append(zero_button_label)
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# Place tickmark labels next to the graduated scale
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for i in range(-1, 6):
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tick_value = Label(FONT_2, text=str((MAX_GR) // 5 * i), color=clue.CYAN)
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if i == -1:
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tick_value.anchor_point = (1.0, 1.1)
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elif i == 5:
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tick_value.anchor_point = (1.0, 0.0)
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else:
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tick_value.anchor_point = (1.0, 0.5)
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tick_value.anchored_position = (99, 201 - (i * 40))
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scale_group.append(tick_value)
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# Place the grams and ounces labels and values near the bottom of the display
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grams_label = Label(FONT_0, text="grams", color=clue.BLUE)
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grams_label.anchor_point = (1.0, 0)
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grams_label.anchored_position = (80, 216)
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scale_group.append(grams_label)
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ounces_label = Label(FONT_0, text="ounces", color=clue.BLUE)
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ounces_label.anchor_point = (1.0, 0)
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ounces_label.anchored_position = (230, 216)
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scale_group.append(ounces_label)
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grams_value = Label(FONT_0, text="0.0", color=clue.WHITE)
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grams_value.anchor_point = (1.0, 0.5)
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grams_value.anchored_position = (80, 200)
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scale_group.append(grams_value)
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ounces_value = Label(FONT_0, text="0.00", color=clue.WHITE)
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ounces_value.anchor_point = (1.0, 0.5)
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ounces_value.anchored_position = (230, 200)
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scale_group.append(ounces_value)
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# Define the moveable indicator bubble
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indicator_group = displayio.Group()
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bubble = Circle(120, 200, 10, fill=clue.YELLOW, outline=clue.YELLOW, stroke=3)
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indicator_group.append(bubble)
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scale_group.append(indicator_group)
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display.show(scale_group)
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# Helpers
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def zero_channel():
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"""Prepare internal amplifier settings and zero the current channel. Use
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after power-up, a new channel is selected, or to adjust for measurement
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drift. Can be used to zero the scale with a tare weight.
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The nau7802.calibrate function used here does not calibrate the load cell,
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but sets the NAU7802 internals to prepare for measuring input signals."""
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nau7802.calibrate("INTERNAL")
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nau7802.calibrate("OFFSET")
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def read(samples=100):
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"""Read and average consecutive raw samples; return averaged value."""
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sample_sum = 0
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sample_count = samples
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while sample_count > 0:
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if nau7802.available:
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sample_sum = sample_sum + nau7802.read()
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sample_count -= 1
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return int(sample_sum / samples)
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# Activate the Sensor
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# Enable the internal analog circuitry, set gain, and zero
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nau7802.enable(True)
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nau7802.gain = DEFAULT_GAIN
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zero_channel()
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# Play "welcome" tones
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clue.play_tone(1660, 0.15)
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clue.play_tone(1440, 0.15)
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# The Primary Code Loop
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# Read sensor, move bubble, and display values
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while True:
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clue.pixel[0] = clue.GREEN # Set status indicator to green (ready)
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# Read the raw scale value and scale for grams and ounces
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value = read(SAMPLE_AVG)
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mass_grams = round(value * CALIB_RATIO, 1)
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mass_ounces = round(mass_grams * 0.03527, 2)
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grams_value.text = f"{mass_grams:5.1f}"
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ounces_value.text = f"{mass_ounces:5.2f}"
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print(f" {mass_grams:5.1f} grams {mass_ounces:5.2f} ounces")
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# Reposition the indicator bubble based on grams value
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min_gr = (MAX_GR // 5) * -1 # Minimum display value
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bubble.y = int(map_range(mass_grams, min_gr, MAX_GR, 240, 0)) - 10
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if mass_grams > MAX_GR or mass_grams < min_gr:
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bubble.fill = clue.RED
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else:
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bubble.fill = None
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# Check to see if the zeroing button is pressed
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if clue.button_a:
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# Zero the sensor
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clue.pixel[0] = clue.RED # Set status indicator to red (stopped)
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bubble.fill = clue.RED # Set bubble center to red (stopped)
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clue.play_tone(1660, 0.3) # Play "button pressed" tone
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zero_channel()
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while clue.button_a:
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# Wait until the button is released
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time.sleep(0.1)
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clue.play_tone(1440, 0.5) # Play "reset completed" tone
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bubble.fill = None # Set bubble center to transparent (ready)
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