PyMata and fast loop

[acca84]

Hello,

I'd like to use pymata to read values from analog port of arduino and display it on a screen using a raspberry pi and pygame. My python code looks like the following :

if __name__ == '__main__':

    val1=board.analog_read(1)/1000
    val2=board.analog_read(2)/1000
    sleep(0.5)
    threading.Thread(target=affiche_pygame).start()     

    while (lecture):
        for event in pygame.event.get():
            if event.type==QUIT:

                lecture=False   
                sleep(0.5)
                pygame.quit()       
                board.close()

                quit()
                sys.exit
            if event.type==pygame.locals.KEYDOWN:

                lecture=False
                sleep(0.5)
                pygame.quit()
                board.close()
                sleep(0.5)
                quit()
                sys.exit

        val1=board.analog_read(1)/1000
        val2=board.analog_read(2)/1000
        sleep(0.1)

        print val1

The thread "affiche_pygame" is an infinite loop wich takes val1 and val2 values and draw a rectangle wich length is calculated using val1 and val2 it works well on a raspberry pi B+ But on a raspberry pi 2 (with fresh image) wich is faster, i can get first analog values then values are not updated, i can see the Arduino Tx light stop blinking after approx 10second.

If i add a sleep(0.1) at the end of the "affiche_pygame" while loop, it works but my animation is not smooth.

Do i stress pymata too much ? If i don't launch the "affiche_pygame" thread, it works well

How can i have updated values without slowing my loop please ? I only want the latest up to date analog value of analog1 and analog2

I hope it's clear, sorry for my poor english.

Regards

I have tested pyfirmata lib and the same problem occurs

[acca84]

i think there is a problem with pygame, because if i remove pygame.display.update() in my "affiche_pygame" function, arduino continues sending data. Memory leak ?

[MrYsLab]

I am not familiar with pygame or its event loop, but I suspect that the problem is integrating your code with the pygame event loop. I doubt if there is a memory leak causing your issues. I solved a similar situation for a tkinter gui I wrote for a pymata_aio project and the solution is documented here. Perhaps this may lead to a solution for your problem.

Since this does not appear to be a pymata issue I am closing this issue. If you feel it should remain open or would like to discuss this further, please feel free to contact me.

[acca84]

ok thanks

I think i have found the problem. Not sure but i think it was a global variable problem