2015-06-23 12:42:35 -07:00

141 lines
3.5 KiB
C

/*
wiring_analog.c - analog input and output
Part of Arduino - http://www.arduino.cc/
Copyright (c) 2005-2006 David A. Mellis
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General
Public License along with this library; if not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330,
Boston, MA 02111-1307 USA
$Id: wiring.c 248 2007-02-03 15:36:30Z mellis $
Modified 28-08-2009 for attiny84 R.Wiersma
Modified 14-10-2009 for attiny45 Saposoft
Corrected 17-05-2010 for ATtiny84 B.Cook
*/
#include "wiring_private.h"
#include "pins_arduino.h"
#include "core_adc.h"
#include "core_pins.h"
#include "core_timers.h"
#include "PwmTimer.h"
uint8_t analog_reference = DEFAULT;
void analogReference(uint8_t mode)
{
// can't actually set the register here because the default setting
// will connect AVCC and the AREF pin, which would cause a short if
// there's something connected to AREF.
// fix? Validate the mode?
analog_reference = mode;
}
int analogRead(uint8_t pin)
{
#if defined( CORE_ANALOG_FIRST )
if ( pin >= CORE_ANALOG_FIRST ) pin -= CORE_ANALOG_FIRST; // allow for channel or pin numbers
#endif
// fix? Validate pin?
ADC_SetVoltageReference( analog_reference );
ADC_SetInputChannel( pin );
ADC_StartConversion();
while( ADC_ConversionInProgress() );
return( ADC_GetDataRegister() );
}
// Right now, PWM output only works on the pins with
// hardware support. These are defined in the appropriate
// pins_*.c file. For the rest of the pins, we default
// to digital output.
void analogWrite(uint8_t pin, int val)
{
// We need to make sure the PWM output is enabled for those pins
// that support it, as we turn it off when digitally reading or
// writing with them. Also, make sure the pin is in output mode
// for consistenty with Wiring, which doesn't require a pinMode
// call for the analog output pins.
pinMode(pin, OUTPUT);
if (val <= 0)
{
digitalWrite(pin, LOW);
}
else if (val >= 255)
{
digitalWrite(pin, HIGH);
}
else
{
#if CORE_PWM_COUNT >= 1
if ( pin == CORE_PWM0_PIN )
{
Pwm0_SetCompareOutputMode( Pwm0_Clear );
Pwm0_SetOutputCompareMatch( val );
}
else
#endif
#if CORE_PWM_COUNT >= 2
if ( pin == CORE_PWM1_PIN )
{
Pwm1_SetCompareOutputMode( Pwm1_Clear );
Pwm1_SetOutputCompareMatch( val );
}
else
#endif
#if CORE_PWM_COUNT >= 3
if ( pin == CORE_PWM2_PIN )
{
Pwm2_SetCompareOutputMode( Pwm2_Clear );
Pwm2_SetOutputCompareMatch( val );
}
else
#endif
#if CORE_PWM_COUNT >= 4
if ( pin == CORE_PWM3_PIN )
{
Pwm3_SetCompareOutputMode( Pwm3_Clear );
Pwm3_SetOutputCompareMatch( val );
}
else
#endif
#if CORE_PWM_COUNT >= 5
#error Only 4 PWM pins are supported. Add more conditions.
#endif
{
if (val < 128)
{
digitalWrite(pin, LOW);
}
else
{
digitalWrite(pin, HIGH);
}
}
}
}