Commit de23a470 authored by Birte Kristina Friesel's avatar Birte Kristina Friesel
Browse files

Arduino: Add ADC driver

parent 7588f9c2

include/arch/arduino-nano/driver/adc.h

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#ifndef ADC_H

#define ADC_H



class AVRADC {

	private:

		AVRADC(AVRADC const &copy);



	public:

		AVRADC() {}



		int16_t getTemp_mdegC(int16_t offset = 205);

		uint16_t getVCC_mV();

};



extern AVRADC adc;



#endif

src/arch/arduino-nano-168/Makefile.inc

+8 −0
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@@ -37,6 +37,10 @@ else ifneq ($(findstring i2c,${arch_drivers}), ) 
	CXX_TARGETS += src/arch/arduino-nano/driver/i2c.cc

endif



ifneq ($(findstring adc,${arch_drivers}), )

	CXX_TARGETS += src/arch/arduino-nano/driver/adc.cc

endif



ifneq ($(findstring spi,${arch_drivers}), )

	CXX_TARGETS += src/arch/arduino-nano/driver/spi.cc

endif
@@ -53,6 +57,10 @@ ifneq ($(findstring counter,${arch_drivers}), ) 
	CXX_TARGETS += src/arch/arduino-nano/driver/counter.cc

endif



ifneq ($(findstring neopixel,${arch_drivers}), )

	CXX_TARGETS += src/arch/arduino-nano/driver/neopixel.cc

endif



ifeq (${cpu_freq}, 16000000)

	uart_baud = 57600

else ifeq (${cpu_freq}, 8000000)

src/arch/arduino-nano/Makefile.inc

+4 −0
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@@ -37,6 +37,10 @@ else ifneq ($(findstring i2c,${arch_drivers}), ) 
	CXX_TARGETS += src/arch/arduino-nano/driver/i2c.cc

endif



ifneq ($(findstring adc,${arch_drivers}), )

	CXX_TARGETS += src/arch/arduino-nano/driver/adc.cc

endif



ifneq ($(findstring spi,${arch_drivers}), )

	CXX_TARGETS += src/arch/arduino-nano/driver/spi.cc

endif

src/arch/arduino-nano/driver/adc.cc

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#include <avr/io.h>



#include "arch.h"

#include "driver/adc.h"



int16_t AVRADC::getTemp_mdegC(int16_t offset)

{

	// Measure temperature probe with 1.1V bandgap reference

	ADMUX = _BV(REFS1) |  _BV(REFS0) | 0x08;



	// Enable ADC with /64 prescaler

	ADCSRA = _BV(ADEN) | _BV(ADPS2);



	// Wait for bandgap to stabilise (70us according to datasheet table 28-3)

	arch.delay_ms(1);



	// Start conversion

	ADCSRA |= _BV(ADSC);



	// Wait for conversion to complete

	while (ADCSRA & _BV(ADSC)) ;



	// typical values: 242 mV @ -45 degC

	// typical values: 314 mV @ +25 degC

	// typical values: 380 mV @ +85 degC

	// slope: 0.9090.. degC / mV at  25 .. 85 degC

	// -> approx. 286.5 mV @ 0 degC / approx -260.45 degC @ 0 mV

	// -> T[degC] = ADC[mV] * 0.91 - 261

	// -> T[mdegC] = ADC[mV] * 91 - 26100

	// slope: 0.9722.. mV / degC at -45 .. 25 degC

	// slope: 0.942    mV / degC at -45 .. 85 degC

	uint8_t adcr_l = ADCL;

	uint8_t adcr_h = ADCH;

	uint16_t adcr = adcr_l + (adcr_h << 8);

	uint16_t vadc = 1100L * adcr / 1023L;



	// adjust for chip-specific variations

	vadc += offset;



	int16_t temp_mdegc = vadc * 91 - 26100L;



	// Disable ADC

	ADCSRA &= ~_BV(ADEN);



	return temp_mdegc;

}



uint16_t AVRADC::getVCC_mV()

{

	// Measure internal 1.1V bandgap using VCC as reference

	ADMUX = _BV(REFS0) | 0x0e;



	// Enable ADC with /64 prescaler

	ADCSRA = _BV(ADEN) | _BV(ADPS2);



	// Wait for bandgap to stabilise (70us according to datasheet table 28-3)

	arch.delay_ms(1);



	// Start conversion

	ADCSRA |= _BV(ADSC);



	// Wait for conversion to complete

	while (ADCSRA & _BV(ADSC)) ;



	uint8_t adcr_l = ADCL;

	uint8_t adcr_h = ADCH;

	uint16_t adcr = adcr_l + (adcr_h << 8);

	uint16_t vcc = 1100L * 1023 / adcr;



	// Disable ADC

	ADCSRA &= ~_BV(ADEN);



	return vcc;

}



AVRADC adc;