Converting ASCII to int in Arduino

Question

I am trying to get user input from the serial monitor to turn a stepper motor according to the input. However my code returns the ASCII value rather than the original input.

#include <Stepper.h>

Stepper small_stepper(steps_per_motor_revolution, 8, 10, 9, 11);

void setup() {
  // Put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("Ready");
}


void loop() {

  // Put your main code here, to run repeatedly:
  int Steps2Take = Serial.read();
  Serial.println(Steps2Take); // Printing
  if (Steps2Take == -1)
    Steps2Take = 0;
  else {
    small_stepper.setSpeed(1000); // Setting speed
    if (Steps2Take > 0)
      small_stepper.step(Steps2Take * 32);
    else
      small_stepper.step(-Steps2Take * 32);
    delay(2);
  }
}

https://www.arduino.cc/en/Serial/ParseInt blocks, which is just nice in your demo case, but will disturb in real scenarios... — datafiddler, Sep 28 '16 at 14:59
Because you are new I want to remark that is is possible to accept, if you like, the answer. There is a little "tip" that will become green :) — Leos313, Sep 28 '16 at 18:10

score 1 · Answer 1 · answered Aug 08 '17 at 10:45

1

Just use the .toInt() function.

You should read the string from your serial and after that convert it to integer.

Serial.print(Serial.readString().toInt());

answered Aug 08 '17 at 10:45

Ali

31
4

score 0 · Answer 2 · answered Apr 28 '21 at 19:22

You could do this three ways! Notice, if the number is greater than 65535 then you have to use a long variable. With decimals use float variable.

You can use the toInt(), or toFloat() which require a String type variable. Heads up as the toFloat() is very time consuming.

   // CODE:
   String _int = "00254";
   String _float = "002.54"; 
   int value1 = _int.toInt();
   float value2 = _float.toFloat();
   Serial.println(value1);
   Serial.println(value2);

   // OUTPUT:
   254
   2.54

You could use the atoi. The function accepts a character array and then converts it to an integer.

   // CODE:
   // For some reason you have to have +1 your final size; if you don't you will get zeros.
   char output[5] = {'1', '.', '2', '3'}; 
   int value1 = atoi(output);
   float value2 = atof(output);
   Serial.print(value1);
   Serial.print(value2);

   // OUTPUT:
   1
   1.23

If you had a Character Array and and wanted to convert it to a string because you didn't know the length...like a message buffer or something, I dunno. You could use this below to change it to a string and then implement the toInt() or toFloat().
```
  // CODE:
  char _int[8];
  String data = "";
  for(int i = 0; i < 8; i++){
    data += (char)_int[i];
  }

  char buf[data.length()+1];
  data.toCharArray(buf, data.length()+1);
```

score -1 · Accepted Answer · edited May 23 '17 at 10:27

-1

If it is just a "type-conversion" problem, you can use something like this:

int a_as_int = (int)'a';

or

#include <stdlib.h>

int num = atoi("23"); //atoi = ascii to integer

as it was point out here.

Does it solve the problem?

edited May 23 '17 at 10:27

Community

1
1

answered Sep 28 '16 at 15:54

Leos313

5,152
6
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69

Converting ASCII to int in Arduino

3 Answers3