Sending signed int data from python to arduino

[hanaa1947]

I am writing a program in python to communicate with arduino. My python program sends signed integers to arduino. x and y are to be sent from python and in arduino i want to retrieve them as it is like x and y separate variables. but so far I have succeded to retrieve data but it is being stored in single variable i.e. x=-13 but I want it like x=-1 and y=3. Could somebody please guide me a way to do it. Thanks

my arduino code:

String a; String b;
 void setup() {
   Serial.begin(9600);
  // Serial.setTimeout(1);
  Serial.println("start");
 }
 
 void loop() {
   if(Serial.available()>0){
    a=Serial.readString();
    b=Serial.readString();
  Serial.println(a);
   Serial.println(b);
   int x = a.toInt();
     int y = b.toInt();
       Serial.print("x="); 
   Serial.println(x); 
     Serial.print("y="); Serial.println(y);  
  }
 }

python code:

 import serial
import time
import math
ser = serial.Serial('COM1',9600,timeout=1)
 time.sleep(1)   
x="-1"
y="3"
print(ser.write(x.encode()))
print(ser.write(y.encode()))

[horace]

in python try printing a newline between printing the two integers
reformat your posted code to remove the > on each line

[hanaa1947]

Done the reformatting. What to do in arduino code for this newline printing in python?

[sumguy]

This link talks about processing serial data and I often use some kind of variation of this example

https://www.gammon.com.au/serial

If you modified the python code to include a newline after each variable then the following arduino code example should capture your data. In my example I have let the variables remain as strings, see if you can get the strings to display at you python program before you move on to converting to integers.

const unsigned int MAX_MESSAGE_LENGTH = 14;
//Create a place to hold the incoming message
static char message[MAX_MESSAGE_LENGTH];
static unsigned int message_pos = 0;


void setup() {
Serial.begin(9600);
}

void loop() {
 //Check to see if anything is available in the serial receive buffer
 while (Serial.available() > 0)
 {
   

   //Read the next available byte in the serial receive buffer
   char inByte = Serial.read();

   //Message coming in (check not terminating character) and guard for over message size
   if ( inByte != '\n' && (message_pos < MAX_MESSAGE_LENGTH - 1) )
   {
     //Add the incoming byte to our message
     message[message_pos] = inByte;
     message_pos++;
   }
   //Full message received...
   else
   {
     //Add null character to string
     message[message_pos] = '\0';

     //Print the message (or do other things)
     Serial.print("Message...");
     Serial.println(message);

     //Reset for the next message
     message_pos = 0;
   }
 }
}

[horace]

python - add newline to transmit of integers - also read text from Arduino

import serial
import time
import math
ser = serial.Serial('COM7',9600,timeout=1)
time.sleep(1)   
x="-1"
y="3"
newline = "\n"
print(ser.write(x.encode()+newline.encode()))
print(ser.write(y.encode()+newline.encode()))
while True:
    if ser.in_waiting > 0:
        buffer = ser.readline()
        ascii = buffer.decode('ascii')
        print('received=', ascii)

arduino - use Serial.parseInt() to read received integers

String a; String b;
void setup() {
  Serial.begin(9600);
  Serial.setTimeout(1000000);
  Serial.println("start");
}

void loop() {
  if (Serial.available() > 0) {
    int x = Serial.parseInt();
    int y = Serial.parseInt();
    Serial.print("x=");
    Serial.println(x);
    Serial.print("y="); Serial.println(y);
  }
}

and the Pythom run output

============================= RESTART: F:\temp\x.py ============================
3
2
received= start

received= x=-1

received= y=3

[hanaa1947]

Thank you so much for providing the solution.

[hanaa1947]

Thanks alot. It works great.