Analog I/O

This library is to input/output an analog signal.

analogReference

Description
Configures the reference voltage used for analog input (i.e. the value used as the top of the input range).
Syntax
analogReference(uint8_t mode)
Parameters
mode:
   DEFAULT: 3.3V
   INTERNAL: 1.1V (internal voltage)
   EXTERNAL: AVREF pin supply voltage
Returns
None

analogRead

Description
Reads the value from the specified analog pin.
Syntax
int analogRead(uint8_t analog_pin)
Parameters
analog_pin: The number of the analog input pin to read from A0(14) to A5(19) and A6(10) to A9(13)
Returns
0 to 4095

analogWrite

Description
Writes an analog value (PWM wave) to a pin. Can be used to light an LED at varying brightnesses or drive a motor at various speeds. The frequency of the PWM signal is approximately 490Hz.
Syntax
analogWrite(uint8_t pin, int value);
Parameters
pin: The number of the pin
value: The duty cycle of the output PWM (0 - 255).
Returns
None

analogWriteDAC

Description
Outputs digital values which it first converts to analog. Unlike analogWrite, it does not output a PWM signal. 3.3V are output when the digital value is 4095.
Syntax
analogWriteDAC(int pin, int value)
Parameters
pin: The number of the pin to write to (24 only)
value: Analog converted value (0 - 4095).
Returns
None

analogWriteFrequency

Description
Change the frequency of PWM from the default of 490Hz. The pins 3, 7, 9, 10, and 13 can be changed.
Syntax
analogWriteFrequency(uint32_t freq);
Parameters
freq: Frequency
Returns
None

Sample Program

The LED on the GR-ROSE board lights up smoothly.


#include <Arduino.h>
void setup(){
}
  
void loop(){
    for(int i = 0; i < 256; i++){
        analogWrite(PIN_LED1, i);
        delay(3);
    }
    for(int i = 0; i < 256; i++){
        analogWrite(PIN_LED1, 256 - i - 1);
        delay(3);
    }
}