Newbie question how re-calculate a/d value to match acual room temp.

Programming Questions

fuzzymurd..

Newbie question how re-calculate a/d value to match acual room temp.

in Programming Questions • 2 years ago

I have got the simple analog to serial arduino program down to the arduino, and it transmit data ( checked via terminal).

Ok then i have got the serielEvent example from prossing site. Then run the program, and the window opens and

i see " received : 432. But the value 432 is just a A/D value (0- 1024). I have the a resistor and a ptc coupled up to

the analog input of the arduino.

The actual room temperature is lets say 20 degrees.

How do i recalculate the value 432 to a read of 20 degrees. I know ofcouse that the hole ideer depends of that my resistor and ptc is linear. Can i add some calculations til the inString line or???, i have not

found any examples like this... How would it look, i got errors when i try to add or divide with inString....

Regards John Hansen, Denmark

Replies(8)

anchnk

Re: Newbie question how re-calculate a/d value to match acual room temp.

2 years ago

Hi,

IIUC, you need to convert your String (inString) to a numerical value (like int or float depends on how much precision you need). You might also need to map your analog range 0-1024 to the degree range, see map reference.

fuzzymurd..

Re: Newbie question how re-calculate a/d value to match acual room temp.

2 years ago

Hi...

And thx for the quick reply....

I got a bit more understanding about this issue... I will now seek for info String to int / float and int to String...

Thx alot...

Regards John Hansen

PhiLho

Re: Newbie question how re-calculate a/d value to match acual room temp.

2 years ago

See int(), float() and str() functions...

fuzzymurd..

Re: Newbie question how re-calculate a/d value to match acual room temp.

2 years ago

Hi and thx for all repl..

I have found out that i can divide the inByte and see the result in process window below processing, but to

get the calulated value back in thie actual processing realy fuzz me around.... Plz bare with me, i am realy

rookie in programming. I am electronic engineer, and if it comes to design circuits no problems.

................

..................

void draw() {

background(0);

text("received: " + inString, 10,50);

}

void serialEvent(Serial p) {

inString = p.readString();

float inByte = float(inString);

println(inByte / 12);

}

PhiLho

Re: Newbie question how re-calculate a/d value to match acual room temp.

2 years ago

Not sure what you mean by " get the calulated value back in thie actual processing".
You can process the value directly in serialEvent, or assign it to a global variable or call a function with this value. It depends on your final purpose.

fuzzymurd..

Re: Newbie question how re-calculate a/d value to match acual room temp.

2 years ago

is it correct that it is NOT possible to devide on a String (serial sent string). I have to convert string to int of float before i can

do some math with it,,,,right??????

Rgd Fuzzy.....

fuzzymurd..

Re: Newbie question how re-calculate a/d value to match acual room temp.

2 years ago

or should i say (received serial string, sent from arduino).....

Jesse Sco..

Re: Newbie question how re-calculate a/d value to match acual room temp.

2 years ago

is it correct that it is NOT possible to devide on a String (serial sent string). I have to convert string to int of float before i can
do some math with it,,,,right??????

I think this has been made abundantly clear... yes, you should convert it. Looks like you already have here:

void draw() {

  background(0);

  text("received: " + inString, 10,50);

}

void serialEvent(Serial p) {

  inString = p.readString();

  float inByte = float(inString);

  println(inByte / 12);

}

Are you having problems printing inByte ? or inByte /12 ?

Have you tried to make a new variable (ie. inByteDivided = inByte / 12; ) ??

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