Storing string from arduino to text file using python

Question

I am using this code to send a string from arduino to PC

int i=0;
void setup(){  
  Serial.begin(9600);    // Open serial connection at a baud rate of 9600
  pinMode(13, OUTPUT);   //set pin13 in o/p mode
}

void loop(){ 
while(1)
{
Serial.write("10.028371,76.328873"); 
Serial.write('\0'); 
delay(1000);
  }
}

I need a python code that receives this string and store it in a text file as such.The arduino is transmitting this string continuously but i need it only once in the text file. I have written the below code but am getting only junk values in the text file

## import the serial library
import serial

## Boolean variable that will represent 
## whether or not the arduino is connected
connected = False

## establish connection to the serial port that your arduino 
## is connected to.

locations=['/dev/ttyUSB0','/dev/ttyUSB1','/dev/ttyUSB2','/dev/ttyUSB3']

for device in locations:
    try:
        print "Trying...",device
        ser = serial.Serial(device, 9600)
        break
    except:
        print "Failed to connect on",device

## loop until the arduino tells us it is ready
while not connected:
    serin = ser.read()
    connected = True

## open text file to store the current 
##gps co-ordinates received from the rover    
text_file = open("position4.txt", 'w')
## read serial data from arduino and 
## write it to the text file 'position.txt'
while ser.read():
    x=ser.read()
    print(x) 
    if x=="\0":
      text_file.seek(0)
      text_file.truncate()   
    text_file.write(x)
    text_file.flush()
## close the serial connection and text file
text_file.close()
ser.close()

have you tried using the repl?

beoliver
– beoliver

2014-01-02 21:53:56 +00:00
Commented Jan 2, 2014 at 21:53 — beoliver
– beoliver, Commented Jan 2, 2014 at 21:53

vishnu varkala · Accepted Answer · 2014-01-04 12:06:26Z

4

solved by making some changes in both arduino and python codes

arduin code:

int i=0;
void setup(){  
  Serial.begin(9600);    // Open serial connection at a baud rate of 9600
  pinMode(13, OUTPUT);   //set pin13 in o/p mode
}

void loop(){ 
while(1)
{
Serial.write('\n'); 
Serial.write("10.028371,76.328873"); 
delay(1000);
  }
}

python code:

## import the serial library
import serial

## Boolean variable that will represent 
## whether or not the arduino is connected
connected = False

## establish connection to the serial port that your arduino 
## is connected to.

locations=['/dev/ttyUSB0','/dev/ttyUSB1','/dev/ttyUSB2','/dev/ttyUSB3']

for device in locations:
    try:
        print "Trying...",device
        ser = serial.Serial(device, 9600)
        break
    except:
        print "Failed to connect on",device

## loop until the arduino tells us it is ready
while not connected:
    serin = ser.read()
    connected = True

## open text file to store the current 
##gps co-ordinates received from the rover    
text_file = open("position4.txt", 'w')
## read serial data from arduino and 
## write it to the text file 'position.txt'
while 1:
    if ser.inWaiting():
        x=ser.read()
        print(x) 
        text_file.write(x)
        if x=="\n":
             text_file.seek(0)
             text_file.truncate()
        text_file.flush()

## close the serial connection and text file
text_file.close()
ser.close()

answered Jan 4, 2014 at 12:06

vishnu varkala

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1 Comment

Flob Over a year ago

i know this post is pretty old, but i have a similar problem and one question: how does the python code know when it has to stop?

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