Sending an integer serially in Arduino

Question

I need to send an integer, say between 0-10000, to Arduino using serial communication. What's the best way of doing that?

I can think of breaking the number into an character array (eg: 500 as '5','0','0') and sending them as a byte stream (yeah, that's ugly). Then reconstruct at the other end. (anything is sent serially as a byte stream, right?)

Isn't there a better way? Somehow, it should be able to assign the value into an int type variable.

(really need to know the same thing about strings too, if possible)

You can also use highByte and lowByte as explained in this answer. — Bill
– Bill, Commented Apr 19 at 15:50

kabr8 · Accepted Answer · 2021-02-06 18:40:12Z

9

If what you're looking for is speed, then instead of sending an ASCII encoded int, you can divide your number into two bytes, here's an example:

uint16_t number = 5703;               // 0001 0110 0100 0111
uint16_t mask   = B11111111;          // 0000 0000 1111 1111
uint8_t first_half   = number >> 8;   // >>>> >>>> 0001 0110
uint8_t sencond_half = number & mask; // ____ ____ 0100 0111
    
Serial.write(first_half);
Serial.write(sencond_half);

edited Feb 6, 2021 at 18:40

kabr8

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answered Dec 17, 2012 at 1:16

NiñoScript

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kabr8 · Accepted Answer · 2021-02-05 23:41:31Z

5

Another way:

unsigned int number = 0x4142; //ASCII characters 'AB';
char *p;
    
p = (char*) &number;
    
Serial.write(p,2);

will return 'BA' on the console (LSB first).

edited Feb 5, 2021 at 23:41

kabr8

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answered Nov 27, 2014 at 21:12

Dave

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Matthew Murdoch · Accepted Answer · 2012-12-16 20:31:18Z

3

You don't specify the from environment, so I assume your troubles is with reading serial data on an Arduino?

Anyways, as can be seen in the Arduino Serial reference, you can read an integer using the Serial.parseInt() method call. You can read strings with eg. Serial.readBytes(buffer, length) but your real issue is to know when to expect a string and when to expect an integer (and what to do if something else comes along, eg. noise or so...)

edited Dec 16, 2012 at 20:31

Matthew Murdoch

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answered Dec 14, 2012 at 10:00

Anders R. Bystrup

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1 Comment

Anubis Over a year ago

Well, the from environment can be considered as PC. But since it's serial communication that sender won't matter, eh? (Ultimately, i'm trying to use this in wireless communication, with APC220). Anyway, thanks. Honestly, i wonder why i didn't see that before. I'll give a try.

kabr8 · Accepted Answer · 2021-02-06 19:59:43Z

1

Other way:

char p[2];
*p = 0x4142; //ASCII characters 'AB'
Serial.write(p,2);

I like this way.

edited Feb 6, 2021 at 19:59

kabr8

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answered May 4, 2016 at 22:02

Reynel Fals de Pedro

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kabr8 · Accepted Answer · 2021-02-06 19:16:28Z

0

I am not from coding background, today i was trying the same and got it working.. I am just sending the number byte wise with start and end bytes added ('a' and 'b'). hope it helps..enter code here

//sending end
unsigned char a,n[4],b;
int mynum=1023;// the integer i am sending
for(i=0;i<4;i++)
{
    n[i]='0'+mynum%10; // extract digit and store it as char
    mynum=mynum/10;
}

SendByteSerially(a);
_delay_ms(5);
SendByteSerially(n[3]);
_delay_ms(5);
SendByteSerially(n[2]);
_delay_ms(5);
SendByteSerially(n[1]);
_delay_ms(5);
SendByteSerially(n[0]);
_delay_ms(5);
SendByteSerially(b);
_delay_ms(100);


//at receiving end. 
while(portOne.available() > 0) 
{
    char inByte = portOne.read();
    if(inByte!='a' && inByte !='b')
    {
    Serial.print(inByte);
    }
    else if(inByte ='a')
        Serial.println();
    else if(inByte ='b')
        Serial.flush();
    }
delay(100);

edited Feb 6, 2021 at 19:16

kabr8

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answered Jan 29, 2015 at 15:51

Akshayrnagendra

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1 Comment

Jan Doggen Over a year ago

This is exactly what the OP describes as 'ugly' and wants to avoid.

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