Serial Communication Arduino to Python

Using Arduino Networking, Protocols, and Devices
#1

I am sending a float value to a python program as follows.

Serial.write((byte)1.001);

Python function to read the data:

def on_buttonClick_runTest(self, button):
        print("\n Beginning Test..")   
        totx    = []
        t = []
        self.port.write('b')
        print ("\n Starting Test") 
        
        self.port.flush()
        
        #Start Sampling Takes 2000 samples  
        
        while len(totx) < 2000:
            totx.append(self.port.read(4))
    
        print("\n Finish") 
        self.port.write('a')
        #Converts to float 
        for i in totx:
            try:
                t.append(struct.unpack('>f', i))
            except:
                pass
        for i in t:
            print(i)
        '''
        for i in totx:
            try:
                temp = float(i)/9.81
                if temp > 16:
                    t.append(0)
                else:    
                    t.append(temp)
            except:
                pass
        
        for i in t:
            print(i)
        '''
        self.port.flush()
        
        #display Figure
        
        fig = pl.figure(figsize= (4.25,4))
        pl.title('G / Samples')
        #Spl.axhline(15)
        pl.plot(t, color="black")
        
        fig.savefig('plot.png')
        self.image_icon.set_from_file("plot.png")
        #fig.show()

and the result I get is this:
(2.5784852031307537e-09,)
(2.5784852031307537e-09,)
(2.5784852031307537e-09,)
(2.5784852031307537e-09,)
…

Can anyone explain this to me. I’ve tried both little and big ended with struct.unpack

#2

ltdouthit:
I am sending a float value to a python program as follows.

Serial.write((byte)1.001);

That can't possibly work. A byte can only contain a value between 0 and 255 so your 1.001 will just be sent as 1

You need to use Serial.print(1.001); which will send the characters "1.001"

Have a look at this Python - Arduino demo

...R

#3