previous value vs. current value of an analog read?

Projects Programming
1

I'm looking to compare two values together, the values being the current value of an analog read and the previous value of an analog read.

I need two variables, one that represents the previous value and one for the current value. How can I define the variable for the previous value?

2

Well the if statement would be where the comparison would be done between two variables the prior and the latest: http://arduino.cc/en/Reference/If

Or did you want someone to write the sketch for you. :wink:

3

I edited my post to make a bit more sense:) I'm unsure as to how I can add a variable for the previous value in my analog read command.

4

You don't "add it" to the analog read command. Can you post your current sketch?

5 
int currentValue;  // global variables are retained on each iteration of loop()
int previousValue;
int analogPin=0;

void setup() {
}

void loop() {
  previousValue = currentValue;  // store what was read last time
  currentValue = analogRead(analogPin);  // get a new reading
  if (previousValue != currentValue) {  // compare them
     // do something, they are different
  } else {
    // do something else, they are the same
  }
}[/code
6

perhaps this.....

  if (currentValue != previousValue) {  // compare them

Amanda

7

commanda:

[quote author=James C4S link=topic=64450.msg469729#msg469729 date=1308533145]

  if (previousValue != previousValue) {  // compare them

perhaps this.....

  if (currentValue != previousValue) {  // compare them

Amanda
[/quote]

:smiley:

8

A good example of why you should always include comments. :wink: