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Fix battery measurement by using calibrated ADC if available #171

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Fix battery measurement by using calibrated ADC if available #171

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8 changes: 3 additions & 5 deletions src/include/System.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,7 @@ double System::readBattery()
#endif
*/
delay(1);
int adc = analogRead(35);
uint32_t batt_mv = analogReadMilliVolts(35);
if (state)
{
pinModeInternal(MCP23017_INT_ADDR, mcpRegsInt, 9, INPUT);
Expand All @@ -140,10 +140,8 @@ double System::readBattery()
digitalWriteInternal(MCP23017_INT_ADDR, mcpRegsInt, 9, LOW);
#endif
*/
// Calculate the voltage using the following formula
// 1.1V is internal ADC reference of ESP32, 3.548133892 is 11dB in linear
// scale (Analog signal is attenuated by 11dB before ESP32 ADC input)
return (double(adc) / 4095 * 1.1 * 3.548133892 * 2);
// divide by 1000 for mv to V, * 2 for voltage divider circuit
return (double(batt_mv) / 1000 * 2);
}

/**
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