Adolfo Reyna
71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
from machine import ADC, Pin
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class BatteryMonitor:
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"""Utility class for monitoring battery voltage and capacity on ESP32-S3-RLCD-4.2."""
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def __init__(self, pin_num=4):
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# Initialize ADC on GPIO 4 with 11dB attenuation
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self.adc = ADC(Pin(pin_num))
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self.adc.atten(ADC.ATTN_11DB)
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def read_voltage(self):
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"""Reads the battery voltage in Volts using internal calibration.
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Returns:
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float: Battery voltage in Volts (e.g. 4.15) or None on error.
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"""
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try:
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# Try calibrated reading in microvolts first
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uv = self.adc.read_uv()
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# 3x voltage divider onboard scales 3.0V-4.2V battery to 1.0V-1.4V
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voltage = (uv / 1_000_000.0) * 3.0
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return round(voltage, 3)
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except AttributeError:
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# Fallback if read_uv() is not supported on older MicroPython builds
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try:
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# Read 12-bit value (0-4095)
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raw = self.adc.read()
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# 3.3V reference at 11dB attenuation, 3x divider
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voltage = (raw / 4095.0) * 3.3 * 3.0
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return round(voltage, 3)
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except Exception as e:
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print(f"Error reading battery raw ADC: {e}")
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return None
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except Exception as e:
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print(f"Error reading battery calibrated ADC: {e}")
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return None
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def read_percentage(self):
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"""Computes approximate battery percentage based on discharge curve.
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Assumes linear approximation between 3.0V (0%) and 4.2V (100%).
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Returns:
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int: Percentage between 0 and 100.
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"""
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voltage = self.read_voltage()
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if voltage is None:
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return 0
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# Bound typical lithium-ion limits
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# 3.0V is typically empty for ESP32 systems where the LDO drops out around 3.3V
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v_min = 3.0
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v_max = 4.2
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if voltage <= v_min:
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return 0
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if voltage >= v_max:
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return 100
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# Linear scaling
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pct = (voltage - v_min) / (v_max - v_min) * 100.0
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return int(pct)
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def get_status_summary(self):
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"""Returns a string description of battery status."""
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v = self.read_voltage()
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p = self.read_percentage()
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if v is None:
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return "Battery: Error"
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return f"Battery: {v:.2f}V ({p}%)"
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