116 lines
3.4 KiB
Python
116 lines
3.4 KiB
Python
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import badger2040
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from machine import Pin, ADC
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import time
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# Global Constants
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MAX_BATTERY_VOLTAGE = 4.0
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MIN_BATTERY_VOLTAGE = 3.2
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WIDTH = badger2040.WIDTH
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HEIGHT = badger2040.HEIGHT
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BATT_WIDTH = 200
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BATT_HEIGHT = 100
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BATT_BORDER = 10
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BATT_TERM_WIDTH = 20
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BATT_TERM_HEIGHT = 50
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BATT_BAR_PADDING = 10
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BATT_BAR_HEIGHT = BATT_HEIGHT - (BATT_BORDER * 2) - (BATT_BAR_PADDING * 2)
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BATT_BAR_START = ((WIDTH - BATT_WIDTH) // 2) + BATT_BORDER + BATT_BAR_PADDING
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BATT_BAR_END = ((WIDTH + BATT_WIDTH) // 2) - BATT_BORDER - BATT_BAR_PADDING
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NUM_BATT_BARS = 4
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# ------------------------------
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# Utility functions
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# ------------------------------
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def map_value(input, in_min, in_max, out_min, out_max):
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return (((input - in_min) * (out_max - out_min)) / (in_max - in_min)) + out_min
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# ------------------------------
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# Drawing functions
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# ------------------------------
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# Draw the frame of the reader
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def draw_battery(level, resolution):
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display.pen(15)
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display.clear()
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display.thickness(1)
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# Draw the battery outline
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display.pen(0)
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display.rectangle((WIDTH - BATT_WIDTH) // 2, (HEIGHT - BATT_HEIGHT) // 2,
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BATT_WIDTH, BATT_HEIGHT)
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display.rectangle((WIDTH + BATT_WIDTH) // 2, (HEIGHT - BATT_TERM_HEIGHT) // 2,
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BATT_TERM_WIDTH, BATT_TERM_HEIGHT)
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display.pen(15)
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display.rectangle((WIDTH - BATT_WIDTH) // 2 + BATT_BORDER, (HEIGHT - BATT_HEIGHT) // 2 + BATT_BORDER,
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BATT_WIDTH - BATT_BORDER * 2, BATT_HEIGHT - BATT_BORDER * 2)
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# Draw the battery bars
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display.pen(0)
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length = (BATT_BAR_END - BATT_BAR_START - ((NUM_BATT_BARS - 1) * BATT_BAR_PADDING)) // NUM_BATT_BARS
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current_level = 0.0
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normalised_level = level / resolution
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for i in range(NUM_BATT_BARS):
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current_level = (1.0 * i) / NUM_BATT_BARS
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if normalised_level > current_level:
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pos = i * (length + BATT_BAR_PADDING)
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display.rectangle(BATT_BAR_START + pos, (HEIGHT - BATT_BAR_HEIGHT) // 2,
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length, BATT_BAR_HEIGHT)
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display.update()
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# ------------------------------
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# Program setup
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# ------------------------------
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# Create a new Badger and set it to update FAST
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display = badger2040.Badger2040()
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display.update_speed(badger2040.UPDATE_FAST)
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# Set up the ADCs for measuring battery voltage
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vbat_adc = ADC(badger2040.PIN_BATTERY)
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vref_adc = ADC(badger2040.PIN_1V2_REF)
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vref_en = Pin(badger2040.PIN_VREF_POWER)
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vref_en.init(Pin.OUT)
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vref_en.value(0)
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# ------------------------------
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# Main program loop
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# ------------------------------
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last_level = -1
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while True:
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# Enable the onboard voltage reference
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vref_en.value(1)
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# Calculate the logic supply voltage, as will be lower that the usual 3.3V when running off low batteries
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vdd = 1.24 * (65535 / vref_adc.read_u16())
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vbat = (vbat_adc.read_u16() / 65535) * 3 * vdd # 3 in this is a gain, not rounding of 3.3V
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# Disable the onboard voltage reference
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vref_en.value(0)
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# Print out the voltage
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print("Battery Voltage = ", vbat, "V", sep="")
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# Convert the voltage to a level to display onscreen
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level = int(map_value(vbat, MIN_BATTERY_VOLTAGE, MAX_BATTERY_VOLTAGE, 0, NUM_BATT_BARS))
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# Only draw if the battery level has changed significantly
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if level != last_level:
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draw_battery(level, NUM_BATT_BARS)
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last_level = level
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time.sleep(1)
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