Combining two python codes for raspberry pi with a servo and ldr sensor

Question

I have Python code running on my raspberry pi 2b and a light sensor, which measures the amount of time it takes for the capacitor of the light sensor to charge and send the pin high:

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)

pin_to_circuit = 7

def rc_time (pin_to_circuit):
    count = 0

    #Output on the pin for 
    GPIO.setup(pin_to_circuit, GPIO.OUT)
    GPIO.output(pin_to_circuit, GPIO.LOW)
    time.sleep(0.1)

    #Change the pin back to input
    GPIO.setup(pin_to_circuit, GPIO.IN)

    #Count until the pin goes high
    while (GPIO.input(pin_to_circuit) == GPIO.LOW):
        count += 1

    if count > 1000000:
        return True
    else:
        return count

#Catch when script is interrupted, cleanup correctly
try:
# Main loop
while True:
    print rc_time(pin_to_circuit)
except KeyboardInterrupt:
    pass
finally:
    GPIO.cleanup()

I want when the count goes higher than 1000000, a MG90S, that I have also connected to the pi and a 4AA battery pack, moves about 90 degrees. The code I was trying to integrate to move the servo:

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)
GPIO.setup(12, GPIO.OUT)

p.ChangeDutyCycle(7.5)  # turn towards 90 degree
time.sleep(1) # sleep 1 second
p.stop()
GPIO.cleanup()

I want to combine these two Python codes. I tried for a bit, but I have almost no Python experience.

Franz · Answer 1 · 2017-06-05T17:35:28.670

You could just integrate the code block you are using to move the MG90S into a function, insert it before or below your def rc_time (pin_to_circuit): (but first you have to define p inside, its not really clear what p refers to):

New Function from second code block:

def move_90_degrees():
    p = '???'
    GPIO.setup(12, GPIO.OUT)
    p.ChangeDutyCycle(7.5)  # turn towards 90 degree
    time.sleep(1) # sleep 1 second
    p.stop()

After defining this function, call it inside your first block like:

if count > 1000000:
    move_90_degrees()
    return True
else:
    return count

That should work.

score 0 · Answer 2 · answered Jun 05 '17 at 13:14

The code is now:

import RPi.GPIO as GPIO
import time

GPIO.setmode(GPIO.BOARD)
pin_to_circuit = 7

def move_90_degrees():
    GPIO.setmode(GPIO.BOARD)
    GPIO.setup(12, GPIO.OUT)
    p = GPIO.PWM(12, 50)
    p.start(7.5)
    p.ChangeDutyCycle(7.5)  # turn towards 90 degree
    time.sleep(1) # sleep 1 second
    p.stop()

def rc_time (pin_to_circuit):
    count = 0

    #Output on the pin for 
    GPIO.setup(pin_to_circuit, GPIO.OUT)
    GPIO.output(pin_to_circuit, GPIO.LOW)
    time.sleep(0.1)

    #Change the pin back to input
    GPIO.setup(pin_to_circuit, GPIO.IN)

    #Count until the pin goes high
    while (GPIO.input(pin_to_circuit) == GPIO.LOW):
        count += 1

    if count > 1000000:
        return True
        move_90_degrees()
    else:
        return count

#Catch when script is interrupted, cleanup correctly
try:
    # Main loop
    while True:
        print rc_time(pin_to_circuit)
except KeyboardInterrupt:
    pass
finally:
    GPIO.cleanup()

The code does print True when the count exceeds 1000000, but the servo still doesn't move. The servo code on its own does however work correctly. (I forgot a bit of the servo code, that's why p wasn't defined, sorry.)

score 0 · Answer 3 · answered Jun 05 '17 at 17:39

I've made a mistake in the code. I changed the order of the function call inside of the

if count > 1000000:
    return True
    move_90_degrees()
else:
    return count

block to :

if count > 1000000:
    move_90_degrees()
    return True
else:
    return count

otherwise, the code returns before the function call is executed. Is it working now?

Combining two python codes for raspberry pi with a servo and ldr sensor

3 Answers3