39 lines
1.2 KiB
Python
39 lines
1.2 KiB
Python
# SPDX-License-Identifier: LGPL-3.0-or-later
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# Copyright (C) 2020 Daniel Thompson
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# Generic lithium ion battery driver
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from machine import Pin, ADC
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class Battery(object):
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def __init__(self, battery, charging, power=None):
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self._battery = ADC(battery)
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self._charging = charging
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self._power = power
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def charging(self):
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return self._charging.value()
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def power(self):
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if self._power:
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return self._power.value()
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return self._charging.value()
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def voltage_mv(self):
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# Assumes a 50/50 voltage divider and a 3.3v power supply
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raw = self._battery.read_u16()
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return (2 * 3300 * raw) // 65535
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def level(self):
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# This is a trivial battery level estimation approach. It is assumes
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# the discharge from 4v to 3.5v is roughly linear and 4v is 100% and
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# that 3.5v is 5%. Below 3.5v the voltage will start to drop pretty
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# sharply to we will drop from 5% to 0% pretty fast... but we'll
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# live with that for now.
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mv = self.voltage_mv()
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level = ((19 * mv) // 100) - 660
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if level > 100:
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return 100
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if level < 0:
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return 0
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return level
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