Arduino and Python (Linux)

Forum 2005-2010 (read only) Software Interfacing
1

Hello,
I wr[ch959]te this code in Python for Linux and module PySerial to echo bytes that sends from computer. The program works fine but i want to tell me your opinion ...

Arduino code:

void setup() 
{ 
  Serial.begin(9600);
}
 
void loop() {
  byte incomingByte;
      if (Serial.available() > 0) {
            incomingByte = Serial.read();
                Serial.println(incomingByte);
      }
}

Python Code:

import serial,sys
ser=serial.Serial('/dev/ttyUSB0',9600, timeout=None)
ser.flushInput()
char = raw_input("Enter String : ")
ser.write(char)
received =[]
for n in range(0, len(char)):
      char_rec = ser.readline()
      received.append(char_rec[0:len(char_rec)-2]) # remove \r\n characters
sys.stdout.write(''.join(received)+'\n')
ser.close()

Screenshot:

Thanks

2

Gosh they're both remarkably similar aren't they. Small foot print too, can it be called from php? if yes, how?

3

Gosh they're both remarkably similar aren't they. Small foot print too, can it be called from php? if yes, how?

In Linux try to change premissions to "Read/Write" to OTHERS in device /dev/ttyUSB0 (as root) .... Maybe this is dangerous but work.. In Windows i think you must change line 2 with $f = fopen("COM1","w+");
You can send data with ....

<?php
$f = fopen("/dev/ttyUSB0","w+");
fwrite($f, "Hello Arduino");
fclose($f);
?>

... and check the output in the terminal .... I dont know yet how receive and use data ...

Screenshot :

4

I write this little program in Python "Temperature" (modules: wx, serial), it reads the temperature from LM35 sensor and sends data to the computer every 1sec...
More : http://george.22web.net/downloads.html

Code:

Wiring:

int therPin = 2,val=0;       
float cel = 0;
char incomingByte;

void setup() {
  Serial.begin(9600);
  pinMode(therPin, OUTPUT);  
}

void loop() {
  if (Serial.available() > 0) {
  incomingByte = Serial.read();
  if(incomingByte=='t' || incomingByte=='T'){
  val = analogRead(therPin); 
  cel = (5.0 * val * 100.0)/1024.0;
  Serial.println((long)cel);
  }
  }  
}

Python:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# generated by wxGlade 0.5 on Tue Apr  8 05:32:21 2008 from /home/george/Desktop/test
# Title : Arduino Temperature version 1.25
# Author : George Hadjikyriacou - 2008

import wx, serial

class MyFrame(wx.Frame):
    def __init__(self, *args, **kwds):
        # begin wxGlade: MyFrame.__init__
        kwds["style"] = wx.DEFAULT_FRAME_STYLE
        wx.Frame.__init__(self, *args, **kwds)
        self.label_1 = wx.StaticText(self, -1, ".: Temperature (LM35) :.", style=wx.ALIGN_CENTER)
      self.label_2 = wx.StaticText(self, -1, "Celsius\t\t: ---", style=wx.ALIGN_LEFT)
      self.label_3 = wx.StaticText(self, -1, "Fahrenheit\t: ---", style=wx.ALIGN_LEFT)
      self.label_4 = wx.StaticText(self, -1, "Kelvin\t\t: ---", style=wx.ALIGN_LEFT)
      self.label_5 = wx.StaticText(self, -1, "George Hadjikyriacou - 2008", style=wx.ALIGN_CENTER)
        self.button_1 = wx.Button(self, -1, "Start")
      self.button_2 = wx.Button(self, -1, "Stop")
        self.__set_properties()
        self.__do_layout()
        self.button_1.Bind(wx.EVT_BUTTON, self.OnClick_1)
      self.button_2.Bind(wx.EVT_BUTTON, self.OnClick_2)
        # end wxGlade
      
    def __set_properties(self):
        # begin wxGlade: MyFrame.__set_properties
        self.SetTitle("Arduino Temperature v1.25")
        self.SetSize((310, 180))
        self.label_1.SetMinSize((310, 17))
      self.label_2.SetMinSize((310, 17))
      self.label_3.SetMinSize((310, 17))
      self.label_4.SetMinSize((310, 17))
      self.label_5.SetMinSize((310, 17))
        self.label_1.SetForegroundColour(wx.Colour(255, 0, 0))
      self.label_2.SetForegroundColour(wx.Colour(0, 0, 255))
      self.label_3.SetForegroundColour(wx.Colour(0, 0, 255))
      self.label_4.SetForegroundColour(wx.Colour(0, 0, 255))
        # end wxGlade

    def __do_layout(self):
        # begin wxGlade: MyFrame.__do_layout
        grid_sizer_1 = wx.FlexGridSizer(6, 1, 10, 0)
      grid_sizer_2 = wx.FlexGridSizer(1, 2, 0, 5)
        grid_sizer_1.Add(self.label_1, 0, 0, 0)
      grid_sizer_1.Add(self.label_2, 0, 0, 0)
      grid_sizer_1.Add(self.label_3, 0, 0, 0)
      grid_sizer_1.Add(self.label_4, 0, 0, 0)
      grid_sizer_1.Add(grid_sizer_2, 0, 0, 0)
        grid_sizer_2.Add(self.button_1, 0, 0, 0)
      grid_sizer_2.Add(self.button_2, 0, 0, 0)
      grid_sizer_1.Add(self.label_5, 0, 0, 0)
        self.SetSizer(grid_sizer_1)
        self.Layout()
        # end wxGlade

    def on_timer(self, event):
      # Set Serial Port and Flush Input ---------------------
      ser=serial.Serial('/dev/ttyUSB0',9600, timeout=None)
      ser.flushInput()
      # Set Serial Port and Flush Input ---------------------
      ser.write("t")
      received =[]
      char_rec = ser.readline()
      cel = float(char_rec)
      far = float((1.8 * cel) + 32)
      kelv = float(cel + 273.15)
      self.label_2.SetLabel("Celsius\t\t: " + "%.2f"%(cel))
      self.label_3.SetLabel("Fahrenheit\t: " + "%.2f"%(far))
      self.label_4.SetLabel("Kelvin\t\t: " + "%.2f"%(kelv))
      ser.close()

    def OnClick_1(self, event): # wxGlade: MyFrame.<event_handler>
      # Start Timer -------------------------------------------
      self.timer = wx.Timer(self, 100)
      self.timer.Start(1000)
      wx.EVT_TIMER(self, 100, self.on_timer)
      # Start Timer -------------------------------------------
        event.Skip()

    def OnClick_2(self, event): # wxGlade: MyFrame.<event_handler>
      # Stop Timer -------------------------------------------
      self.timer.Stop()
      self.label_2.SetLabel("Celsius\t\t: ---")
      self.label_3.SetLabel("Fahrenheit\t: ---")
      self.label_4.SetLabel("Kelvin\t\t: ---")
      # Stop Timer -------------------------------------------
        event.Skip()

# end of class MyFrame

if __name__ == "__main__":
      app = wx.PySimpleApp(0)
      wx.InitAllImageHandlers()
      frame_1 = MyFrame(None, -1, "")
      app.SetTopWindow(frame_1)
      frame_1.Show()
      app.MainLoop()

Screenshot:

5

Also you can use floatToString.h ( Arduino Playground - FloatToString ) for exactness ....

for example :

#include "floatToString.h"

int therPin = 2;       
float cel = 0;
char incomingByte;
char temperature[10];  
  
void setup() {
  Serial.begin(9600);
  pinMode(therPin, INPUT);

}

void loop() {
  if (Serial.available() > 0) {
  incomingByte = Serial.read();
  if(incomingByte=='t' || incomingByte=='T'){
  cel = (5.0 * analogRead(therPin) * 100.0)/1023.0;
  Serial.println(floatToString(temperature,cel,2));
  }
  }  
}