Arduino Forum

Using Arduino => Project Guidance => Topic started by: iKinkyxD on Mar 06, 2012, 06:09 pm

Title: Shutdown Button
Post by: iKinkyxD on Mar 06, 2012, 06:09 pm
Hello There

i was wondering if i were able to add a button to my Arduino Duemilanove on 1 of the Digital pins
and make it shutdown some of the others ?

For example im trying to shutdown my lcd, and i want a button to turn it on and off.

and maybe add a potentiometer for the brightness / Contrast.

Any idea ?

Thanks in advance
Title: Re: Shutdown Button
Post by: cmagagna on Mar 06, 2012, 06:20 pm
No problem. Connect another pin to a transistor, and that transistor to the power for your LCD. If you Google "arduino transistor" you'll find a ton of tutorials; here's one:

http://art511.wordpress.com/works-in-progress/how-to-use-a-transistor-as-a-switch/

As far as the potentiometers for brightness / contrast -- most LCDs have pot connections for contrast adjust so you won't need the Arduino there. For brightness you could either connect the pot directly to the LCD's backlight or you could connect the backlight to a PWM pin on your Arduino and adjust it in your program.

Good luck!
Title: Re: Shutdown Button
Post by: iKinkyxD on Mar 06, 2012, 07:50 pm
Thanks for your quick reply !!

But i was wondering if i could just add a button to a digital pin and maybe put some code in that tells the
arduino to close those pins, og stop the output ?

Title: Re: Shutdown Button
Post by: cmagagna on Mar 06, 2012, 10:41 pm
Hi, I'm sorry but I don't understand.

Can you add a button to a digital pin? Yes, that is easy.

Can you put some code in that tells the arduino to close the pins? Yes, but close what pins? Do you mean the pins you use for the LCD? Yes you can turn those off but isn't the LCD power line run directly to the Arduino power?
Title: Re: Shutdown Button
Post by: iKinkyxD on Mar 07, 2012, 09:14 am
Thats exactly what i mean, by turning some digital pins off so the lcd wont display anything but the rest of the system runs as usually.
But maybe just add a button to the powerline andthe arduino, would that be easier ?
Title: Re: Shutdown Button
Post by: SnJDK on Mar 07, 2012, 09:30 am
Maybe to conclude :
You would like to use button switch to tell Arduino program to turn off LCD display.

You may do that using standard schematic for digital/analogue push button input line and digital to transistor output line.

Title: Re: Shutdown Button
Post by: retrolefty on Mar 07, 2012, 09:57 am
Quote
Thats exactly what i mean, by turning some digital pins off so the lcd wont display anything but the rest of the system runs as usually.
But maybe just add a button to the powerline andthe arduino, would that be easier
?


Best way is to just include the code logic in your sketch to decide if the display should be active and updating or not based on the input state of the added 'shutdown button'.
Title: Re: Shutdown Button
Post by: iKinkyxD on Mar 08, 2012, 08:22 am
Exactly what meant retrolefty.
Maybe you can give an example for it?
Because om not that good at coding yet.
Title: Re: Shutdown Button
Post by: iKinkyxD on Mar 23, 2012, 02:54 pm
No one ?
Title: Re: Shutdown Button
Post by: AWOL on Mar 23, 2012, 03:18 pm
Quote
Maybe you can give an example for it?

We can't give an example because we don't know what your code looks like.
Title: Re: Shutdown Button
Post by: woody_unreal on Mar 23, 2012, 06:42 pm
Wonder if hes asking for something like - if button 1 = high then pin 5 = low(transistor off)?
Title: Re: Shutdown Button
Post by: Sacman on Mar 24, 2012, 12:05 am
I don't think he gets the transistor part yet.

Is this just to save battery power. If you completely turn the LCD off, you will erase whatever data is on the LCD. To prevent this you want to just turn off the backlight if your particular display allows that (mine doesn't and it sucks).

Take a look at this series of tutorials. I found it to be the best place to start for a new Arduino user:

http://www.youtube.com/watch?v=fCxzA9_kg6s&feature=list_related&playnext=1&list=SPA567CE235D39FA84 (http://www.youtube.com/watch?v=fCxzA9_kg6s&feature=list_related&playnext=1&list=SPA567CE235D39FA84)
Title: Re: Shutdown Button
Post by: woody_unreal on Mar 24, 2012, 01:55 am
Wa hoo Mr Blum, Has many Tutorials for the Arduino, its almost a must for the introduction.