How to compile AVR code in Arduino?

Question

Why does the following code not work in Arduino?

#include<avr/io.h>
void setup()
{
    DDRA = 0xFF;
}
void loop()
{
    PORTA = 0xAA;
    _delay_ms(1000);
    PORTA = 0x55;
    _delay_ms(1000);
}

I get the following error. "DDRA was not declared in this scope."

As I know, arduino uses AVR microcontrollers, so why can't we use AVR code in arduino boards?

user2461391 · Accepted Answer · 2013-07-23 13:51:39Z

5

The normal AVR chips used in Arduinos do not have a port A register, usually it is B/C/D .

answered Jul 23, 2013 at 13:51

user2461391

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Comments

Jeff · Accepted Answer · 2013-07-23 16:29:06Z

3

User261391 has the first issue with your code. You will then quickly find you also need to include delay.h for the delay to work.

Revised Example:

#include<avr/io.h>
#include<avr/delay.h>
void setup()
{
    DDRB = 0xFF;
}
void loop()
{
    PORTB = 0xAA;
    _delay_ms(1000);
    PORTB = 0x55;
    _delay_ms(1000);
}

answered Jul 23, 2013 at 16:29

Jeff

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Comments

KernelPanic · Accepted Answer · 2013-07-23 11:40:00Z

0

Did you maybe forget to include some library?

answered Jul 23, 2013 at 11:40

KernelPanic

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1 Comment

Akshat Over a year ago

I included avr/io.h Forgot to mention in the code. Now updated!

zx485 · Accepted Answer · 2017-01-16 00:23:22Z

0

I had the same problem...

The thing is that the Arduino type is probably set to Arduino Uno, which has a different DDRA defined(I guess)... You can set the type in

TOOLS->Board->Arduino Mega 2560

if you only want to compile it and see if the code has no error.

edited Jan 16, 2017 at 0:23

zx485

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answered Jan 16, 2017 at 0:04

Alex

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