1

I am writing a code for Ultrasonic distance sensor. I have wired all the things perfectly and written the code for it but somehow it gives a runtime error of the channel already being in use. Below is my code:

import RPi.GPIO as gpio import time def distance(measure = 'cm'): gpio.setmode(gpio.BOARD) gpio.setup(12, gpio.OUT) #Here it gives error of channel in use gpio.setup(16, gpio.IN) gpio.output(12, False) #it doesn't show me any value of distance while(gpio.input(16) == 0): nosig = time.time() while(gpio.input(16) == 1): sig = time.time() t = sig - nosig if(measure == 'cm'): distance = t / 0.000058 elif(measure == 'in'): distance = t / 0.000148 else: print('improper measurement: inches or centimeters') distance = None gpio.cleanup() return distance() print(distance('cm'))
Improve this question
1
  • In future please post 'proper' code, without the pointed arrows at the start of the line. You probably copied this in IDLE. Much better to use a text editor / IDE instead of the IDLE interpreter. Commented Feb 6, 2019 at 15:54

1 Answer 1

Reset to default
1

That's because you're running gpio.setup() on that pin every time you call that function. You need to run setmode and setup once, and then just check the distance in the function.

gpio.setmode(gpio.BOARD) gpio.setup(12, gpio.OUT) #Here it gives error of channel in use gpio.setup(16, gpio.IN) def distance(measure = 'cm'): gpio.output(12, False) ...

You might find it easier to use gpiozero's DistanceSensor class instead.

Improve this answer
2
  • No, the program should run atleast once but, when i run it it executes but doesn't show any values of distance. I don't know whether it's because of GPIO pin issue or something else but, the sensor doesn't seem to be receiving the input somehow. Commented Feb 6, 2019 at 15:02
  • @MuhammadHassan - well, you still need to move the setup code outside the function def, so that it will only be run once. As Ben says: the error you get is a result of the repeated init calls. Debugging can continue after you corrected that. Commented Feb 6, 2019 at 15:58

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.