Analog I/O

Digital I/O
Analog I/O
Advanced I/O
Time
Math
Trigonometry
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Interrupts
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Servo Motor
Stepping Motor
Character LCD
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I²C (Wire)
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Periodic Operation
Clock (RTC)
Utility

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). When input is the same as the reference voltage, the analogRead function returns 1023. For example, default is set to the Arduino compatible reference voltage 5.0V, therefore, when 3.3V is applied, 675 is returned. However, note that 5V cannot be applied. When RAW12BIT (for 12-bit A/D conversion) is set to the reference voltage, 4095 is returned.

Syntax

analogReference(uint8_t mode)

Parameters

mode:
DEFAULT： 5.0V (Arduino compatible)
INTERNAL： 1.1V (internal voltage)
EXTERNAL: AVREF pin supply voltage
RAW12BIT： 3.3V (for 12-bit A/D conversion)

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 A7 (21)

Returns

int 0 to 1023; for 12-bit A/D conversion, 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 to write to (max 15 pins)
value: The duty cycle of the output PWM (0 - 255).

Returns

None

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

#include <Arduino.h>
unsigned char ledpat[6][4] = {
    { 20, 50, 100, 200 },
    {  50,100,200,  20 },
    { 100,200, 20,  50 },
    { 200, 20, 50, 100 },
    { 100,200, 20,  50 },
    {  50,100,200,  20 },
};
 
void setup()
{
    pinMode(PIN_LED0,OUTPUT);
    pinMode(PIN_LED1,OUTPUT);
    pinMode(PIN_LED2,OUTPUT);
    pinMode(PIN_LED3,OUTPUT);
}
 
void loop()
{
    int i;
    for (i = 0; i < 6; i++){
        analogWrite(PIN_LED0, ledpat[i][0]);
        analogWrite(PIN_LED1, ledpat[i][1]);
        analogWrite(PIN_LED2, ledpat[i][2]);
        analogWrite(PIN_LED3, ledpat[i][3]);
        delay(100);
    }
}