Arduino to python serial read split

Question

Hi I am staring out and have cracked sending multiple bits of information from Python to my Arduino. I now would like to send information from my Arduino to python I have looked at may examples but they all send to show only one line of information being sent.

his is what i am stuck with.The Arduino is sending a start number 255 then an ID then the information it looks like this on the terminal window.

255 start chr
1 ch ID
99 Value

I want to split these back into there individual arrays in python.

thanks for any tips.

• Eric: Is the arduino actually outputting " start chr"? Are there two newlines between values? Or do you receive 255199?
• james jordan: it just outputs 255 1 99 on separate lines. i would like to get them into data0 data1 data2.

Answer 1

The easiest way is to use a dedicated separator character (e.g. a comma) and split the strings accordingly. That is: write the Arduino side of your code in such a way that parsing on the Python side becomes easy.

• james jordan: don't know what you mean but my arduino Serial.print(data0) Serial.print(data1) Serial.print(data2)
• Eric: @jamesjordan: print or println? That code would produce 255199, which is impossible to parse.

Answer 2

Print the Arduino items into a line with a delimiter such as a comma like so:

 Serial.print(VALUE 1);
 Serial.print((" , "));
 Serial.print(VALUE 2);
 Serial.print((" , ")); 
 Serial.println(LAST VALUE);

Using println for the last value will combine all previous print into one line. With Arduino Serial Monitor results something like this:

VALUE 1 , VALUE 2 , LAST VALUE

You can easily split the values in python and assign a variable to each value like taking values from an array:

SERIALDATA= sensorData.readline() #Read line of text from Arduino
DATASPLIT= SERIALDATA.split(' , ') #Splits the line of text into array of strings composed of each individual sensor data
pyVALUE1= DATASPLIT [0]
pyVALUE2= DATASPLIT [1]
pyFINALVAL= DATASPLIT [2]