How to check current state of GPIO pin via Python?

Question

I want to check state of GPIO pin when I start, a porgram. For example I have another program which changing state of pin ( if is low change to hihg, and if is high change to low). And now I want to write program what will be read current state of pin. But when I'll do this:

import RPi.GPIO as GP
GP.setmode(GP.BOARD)
NRpin=40
GP.setup(NRpin,GP.OUT) #now GPIO state is set to default (0)

when I am doing

 GP.setup(NRpin,GP.OUT)

current state is replacing default state (low).

The question is: If is there any way to check current state?

I know I can do like this:

import RPi.GPIO as GP
import subprocess as sub
a=sub.check_output(['sudo', 'gpio', '-g','read','21'])
print a

but what if I don't have installed wiringpi on my Raspberry Pi? (gpio command is in wiringpi package).

I suppose it can look like:

if GP.output(NRpin,1)==True:
  print "HI"
elif GP.output(NRpin,0)==True:
  print "LO"

but without:

GP.setup(NRpin,GP.OUT)

I cannot use that code.

Give me some advices, prease:)

Koxo Koxo · Accepted Answer · 2018-10-30T12:43:59

With function GPIO.gpio_function(pin) you can determine if pin is set like INPUT or OUTPUT.

To check if INPUT is HIGH or LOW, you can use if(GPIO.input(channel)==GPIO.LOW)) or if(GPIO.input(channel)==GPIO.HIGH))

How to check current state of GPIO pin via Python?

1 Answers