Analog pins on Arduino board is default pin used as analog
input. In this pin you can measure analog voltage from 0 - 5V continuously. So input
voltage with a value of 1V, 1.1V, 2V, 2.7V up to 5V can easily read through
this pin. Typically, an Arduino board has more than one pin Analog. For
example, the Arduino Uno board has 6 analog pins namely ‘A0’, ‘A1’ until ‘A5’.
For Arduino Mega, the board has more analog pins (16 pcs).
If we look at Arduino as an entity, the A0 – A5 pins, as the
name implies, is intended as an analog pin. But if we look further, an Arduino
board is a control board with microcontroller AVR ATmega as main component. So,
it can be said that Arduino analog pins has more functionality than just analog
measurement. Consider Arduino pinout diagram as follows:
Note that A0 - A5 pin in Arduino (Uno) is actually PC0 - PC5
pin (Port C.0 - Port C.5) belonging ATmega microcontroller IC. As we know
through the datasheet, each microcontroller pin is designed to have a dual
function, as a digital input or digital output pin. In addition, in some of the
pins also have special functions such as input ADC / Analog to Digital Converter
(pin PC0 - PC5), as analog output with PWM ( Pulse Width Modulation) method
(PD3, PD5, PD6, PB1, PB2, PB3), as serial function in PD0 and PD1 pins and so
on. For more detail about microcontroller ATmega pins into Arduino board mapping,
can be read on a pinout diagram as follows:
Pinout diagram from picture above explains that Arduino analog
pin at pin A0 - A5 can also be activated as regular digital pins because it was
actually pin PC0 - PC5 in AVR ATmega microcontroller. Just because Arduino is designed
as compact board, then the pins are enabled as analog pin only. However, once
again, this pin can be used as a digital input / output pin as usual. How to do
it, please refer to the tutorial below:
Arduino Analog Pin as Digital Output Pin
To enable Arduino analog pin as digital output pin, do
relatively the same as a regular digital pins. You can call this analog pin
with the alias name of 'A0', 'A1' until 'A5'). For example:
pinMode (A0, OUTPUT);
digitalWrite (A0, HIGH);
The first line will make analog pin ‘A0’ as a digital output
pin. While on next line you would issue a 'HIGH' logical voltage (5V or logic
'1') to this pin.
Note: do not forget to put the code 'pinMode (a, b);’ in void setup ()
Arduino Analog Pin as
Digital Input Pin
To set Arduino analog pin as a digital input pin is somewhat
different way. You need to know, the PC0 -PC5 pins are connected with internal
pull-up resistor inside ATmega microcontroller. Thus the trick to make Arduino
analog pin into a digital input pin is to issue 'HIGH' logical voltage to the
analog pin without calling pinMode (a, b); function first. For example:
Void setup () {
digitalWrite (A0, HIGH);
}
Note that a declaration setting of analog pin as digital
input should be done in declaration void setup () block as in example above.
After you write the source code above, then the analog pin 'A0' will function
as a normal digital input pin and can be used to detect digital input (e.g.
keystrokes, button or limit switch) with digitalRead () function . For example:
A5status int = 0;
Void setup () {
digitalWrite (A0,
HIGH);
}
A5status = digitalRead (A5);
If (A5status == 0) {
digitalWrite (13, HIGH)
}
else {
digitalWrite (13, LOW)
}
Example sketch above is intended to turn on / off internal LED
on Arduino board (connected to pin 13) based on status of pin A5. If the value
is ‘0’ (the button is pressed), the LED will light up, and if the value '1'
(the button is released) the LED will turn off.
So, this is an Arduino tutorial on how to configure Arduino analog pins as digital pins either as
input or digital output, may be useful for you. If you have any questions can
be submitted in the comments column below. Thanks.
A blogger, electro-hobbyst, freelancer n technopreneur. I'm an Indonesian, I did my best to make tutorial without spelling errors, please CMIIW or if something burned your eyes..
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