Pages: [1]   Go Down
Author Topic: Calculating Circuits for Arduino  (Read 521 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 7
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hello, I have taken some general classes on circuits. I would like to know how to treat the pins on the Arduino. For example I have 6 photoresistors I would like to connect to the 6 analog pins on the Arduino board. Should I treat them as 6 different circuits or 6 resistors in parallel?
Logged

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 637
Posts: 34579
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Six diffrent circuits.
Logged

Anaheim CA.
Offline Offline
Faraday Member
**
Karma: 47
Posts: 2928
...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Also need pull-ups or downs depending on what you wish to accomplish.

Bob
Logged

--> WA7EMS <--
“The solution of every problem is another problem.” -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Offline Offline
Newbie
*
Karma: 0
Posts: 7
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks grumpy.

What is a pull up/down?
Logged

Danger Boy
Offline Offline
Edison Member
*
Karma: 14
Posts: 1108
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks grumpy.

What is a pull up/down?

A pull up resistor is a resistor, usually of a high value (anywhere from approximately 1K to 100K with 10K being pretty common but it depends on the situation) between part of the circuit and the high rail, usually 5V for Arduino projects, but it could be 3.3V for the low power systems.  A pull down resistor is the same but to the low rail - 0V.  The point is to pull that part of the circuit to either of the voltages when the circuit goes into the high impedance state of neither voltage being connected.  If that part of the circuit is never in high impedance or the circuit consuming the signal can't misbehave because of high impedance (like an LED) you will never need a pull up or a pull down.

Wikipedia says it even better than I do, and with diagrams:

http://en.wikipedia.org/wiki/Pull-up_resistor
« Last Edit: September 30, 2012, 01:44:20 am by JoeN » Logged

I have only come here seeking knowledge. Things they would not teach me of in college.

Manchester (England England)
Offline Offline
Brattain Member
*****
Karma: 637
Posts: 34579
Solder is electric glue
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Or look how I describe it:-
http://www.thebox.myzen.co.uk/Tutorial/Inputs.html
For when the pins are inputs.
Logged

Pages: [1]   Go Up
Jump to: