Programming Virtual Robot to do 2 tasks at the same time. Please help

[des.marco]

Hi,

Could someone please help to debug my code. I am new in Python programming and I wanted to make my robot scan the ‘barcode’ and at the same time count the ‘inventory boxes’ on the left. I tried doing it in Python Project using a function but my variable ‘inventory’ doesn’t increase the value whenever the distance sensor reads < 30cm. In the end, the display always shows ‘None’. Here is my Python Project link: https://www.robotmesh.com/studio/60a7162ad2cf776482d02749

I tried an alternative way in a Blockly Project to learn using a thread. However, the problem still persist. My variable on thread2 doesn’t count up. Here is my Blockly Project link: https://www.robotmesh.com/studio/60aafe5dd07e4038a62aaf82

I have no problem in scanning my ‘barcode line segments’, my only problem is to count the boxes.

Looking forward to your suggestions.

Thank you.

Marco

[Sam]

Hi Marco.

When you define detectLines() you have this code:

def detectLines():
    global inventory    
    inventory = 0

Later, you have this code:

# call detectLines function for 4 times. Store the letter to scannedLetters list for every iteration.
for i in range(5):
    scannedLetter[i] = detectLines()
vexiq.lcd_write('Inventory = ' + str(inventory), 3)

You zero out inventory every time detectLines() is called. As a result, it’s 0 when you try to print it. If you want to hold on to the contents of that variable to use later, don’t set it to 0.

Cheers, Sam.

[des.marco]

Hi Sam,

Thank you for your advice. However, after deleting the code “inventory = 0” in my detectLines function I encountered this error:

Please help.

Thank you.

Marco

[Sam]

It is throwing a name error because you haven’t defined inventory yet. Move inventory = 0 outside of the function.