arduino mega anaolog pins as outputs

Projects General Guidance
1

Hi there,

I'm using an arduino mega to turn 12v RGB leds on and off via an LM298 module. Easy enough and the standard digital IO pins up to 53 work as expected .

However when I assign the analog outputs (pins 54 - 69) as outputs they don't function as expected. Strangely the LEDs turn on but not off. . . but sometimes if i toggle another random output they do switch off. .

Is there something else I need to consider when using analog in pins as outputs? Do I need pull up/down resistors or something etc?

many thanks

2

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.
http://forum.arduino.cc/index.php/topic,148850.0.html .
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

We need to see your code, please.

Thanks.. Tom... :slight_smile:

3

thanks for your reply. I'm using firmata to control the board via the program 'pure data'. I believe that might be the problem, after further tests it seems the firmata doesn't work properly with a mega which is a shame. Thanks for your reply

4

I have never used Firmata but I know that the analog pins on an Uno or Mega can be used as normal digital I/O pins

...R

5

Hi,
Have you written a simple bit of code to prove your theory?
That is code that just concerns those two outputs?

Thanks.. Tom.. :slight_smile:

6

TomGeorge:
Have you written a simple bit of code to prove your theory?

I assume your "you" refers to the OP rather than to my Reply #3.

If I am wrong please let me know.

...R

7

Hi,
@bananaplug
Have you written a simple bit of code to prove your theory?
That is code that just concerns those two outputs?

Thanks.. Tom.. :)

8

bananaplug:
...to turn 12v RGB leds on and off via an LM298 module...

Did you compensate for the fact that an LM298 (L298) 'looses' several volts.
You might need a 15volt supply for your 12volt LEDs.
Or dump that L298, and use a logic level mosfet (as everybode else does).
Leo..

9

Hi,
How do you define the analog pins as output.

pinMode(54,OUTPUT);

or

pinMode(A0,OUTPUT);

Tom... :slight_smile:

10

ARDUINO ANALOG PINS ARE USED AS DIGITAL PINS ALSO.....

I WORKED THIS TYPE OF CIRCUITS IN MY REAL-TIME EXAMPLES....