Storing an 8bit number as a variable.

Projects General Guidance
1

I just got an Arduino Uno and I'm trying to use it on a project where I can turn a pot and using a voltage divider be able to store the value as a variable. In other words, I'm using a potentiometer as a voltage divider, running it through a A/D converter then through a Parallel to Serial IC where it comes out as an 8 bit binary number and I want to store that number as a variable where I can compare numbers to it. Is this even possible? Is there an easier way?

If this makes no sense let me know because I am having trouble understanding what I'm doing.

Warning: I have only ever programed in Java so please dumb everything down.

Thank you so much!

2

Like

byte analogValue = analogRead(myPin) / 4;

?

3

AWOL
Thanks for the quick response. This is my first time ever using a microprocessor let alone an arduino, so that code makes no sense to me. From what I understand it reads in an analog signal on a selected pin, divides that by 4 and stores as a byte? If so then I don't think that's what I'm looking for.

4

Well, if you can explain why you need an external A to D when the Arduino already has one?

5

poor choice of variable name ... :. (gets compile error) Slightly better is

bytevalue = analogRead(A0) / 4;

We're assuming here that the output of your voltage divider is connected to analog input pin 0 on the Arduino ("A0" is predefined to this pin in ver.22, it is another improvment I sneaked in :. )

6

Msquare, so if i plug the output of my voltage divider into pin0 that code would store a value between 0-255 in the variable "bytevalue". One quick question, what is the voltage that it would be comparing my output to? From what I understand a voltage divider would give me a voltage between 0-5v (since im putting 5v into the pot), and the A-D converter put it into a number between 0-255 relative to the voltage that the A-D converter is running at, so what voltage would the Arduino be comparing it to?

Sorry if im an idiot.

7

The default analogue reference is the supply voltage, so for most Arduinos, this is 5V.
The converter is a 10 bit (0...1023) device, so we divide by 4 to fit the value into a byte.
http://arduino.cc/en/Reference/AnalogRead

8

AWOL,

Thank you very much you answered exactly what I needed, I appreciate it!