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support measure battery voltage #73

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575f830
support measure battery voltage
cheng3100 Feb 7, 2019
14be4e5
Merge branch 'master' into dev
cheng3100 Jun 1, 2021
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2 changes: 2 additions & 0 deletions cores/arduino/Arduino.h
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Original file line number Diff line number Diff line change
Expand Up @@ -137,6 +137,8 @@ int digitalRead(uint8_t pin);
int analogRead(uint8_t pin);
void analogReference(uint8_t mode);
void analogWrite(uint8_t pin, int val);
float batteryVoltageRead(void);


unsigned long millis(void);
unsigned long micros(void);
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45 changes: 45 additions & 0 deletions cores/arduino/wiring_analog.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,51 @@

uint8_t analog_reference = DEFAULT;


float batteryVoltageRead(void)
{
#if defined(__AVR_ATmega32U4__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
#define ADMUX_VCCWRT1V1 (_BV(REFS0) | _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1))
#elif defined (__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny84__)
#define ADMUX_VCCWRT1V1 (_BV(MUX5) | _BV(MUX0))
#elif defined (__AVR_ATtiny25__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
#define ADMUX_VCCWRT1V1 (_BV(MUX3) | _BV(MUX2))
#else
#define ADMUX_VCCWRT1V1 (_BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1))
#endif

// Read 1.1V reference against AVcc
// set the reference to Vcc and the measurement to the internal 1.1V reference
#if defined(ADMUX)
if (ADMUX != ADMUX_VCCWRT1V1)
{
ADMUX = ADMUX_VCCWRT1V1;

// Bandgap reference start-up time: max 70us
// Wait for Vref to settle.
delayMicroseconds(350);
}
#endif

#if defined(ADCSRA) && defined(ADCL)
// Start conversion and wait for it to finish.
ADCSRA |= _BV(ADSC);
while (bit_is_set(ADCSRA,ADSC)) {};

// Result is now stored in ADC.

// Calculate Vcc (in V)
float vcc = 1.1*1024.0 / ADC;

return vcc;

#else
return 0;
#endif
}



void analogReference(uint8_t mode)
{
// can't actually set the register here because the default setting
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