inteface with switches

[atux_null]

i am learning how to interface esp8266 nodemcu with hardware. I am following the guide from https://learn.adafruit.com/micropython- ... tal-inputs. I have attached in a linux machine the board and through

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screen /dev/ttyUSB 115200

i got the console of it. The i connect a cable to Ground of the board and another cable to D6. Then each end goes to the switch.
By issuing in the console

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>>> import machine
>>> button = machine.Pin(12, machine.Pin.IN, machine.Pin.PULL_UP)
>>> button.value()

i get 1 if the button is not pressed, and if i keep the button pressed and then issue

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button.value()

then i get 0. That means my setup is correct as well the code. The problem is when i am doing the while loop. the code:

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import machine
import time
button = machine.Pin(12, machine.Pin.IN, machine.Pin.PULL_UP)
while True:
    first = button.value()
    time.sleep(0.01)
    second = button.value()
    if first and not second:
        print('Button pressed!')
    elif not first and second:
        print('Button released!')

what i am doing is, while in >>> i issue ctrl-e to enter paster mode. then i paste the code. I do not exit and then i press the button on the switch. without anything to happen on the console.

another test is to stay at the >>> mode and paste the code. pressing the button nothing changes. CTRL-C exits and returns:

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...
Traceback (most recent call last):
  File "<stdin>", line 7
SyntaxError: invalid syntax

i am missing something over here.

[pythoncoder]

It works on a Pyboard (just changing the pin ID) so I'm not sure what's going wrong for you.

[atux_null]

i was wondering if i am in a wrong state of repl and needs to be somewhere else. how can i overcome the problem and see the output on the screen please?

[OutoftheBOTS_]

It is a bit of an unusual bit of code to do the task that your trying to do.

The switch must change state during this time.sleep(0.01) lines of code of nothing will happen

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    first = button.value()
    time.sleep(0.01)
    second = button.value()

You would normally do something more like this

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import machine
import time
button = machine.Pin(12, machine.Pin.IN, machine.Pin.PULL_UP)

#initilize old_state
old_state = button.value()

while True:    
	new_state = button.value()    
	
	#check to see if stae has changed
	if new_state != old_state:
        	if new_state: print('Button released!')
        	else: print('Button pressed!')

[atux_null]

thanks a lot for the reply.
the code is a copy from adafruit. as i mentioned before i am trying to learn micropython and interfacing the esp with hardware, so i used their code.
in order to run your code i am about to do the following:
-in a linux shell connect through screen to the console of the esp8266 nodemcu
-while in repl paste one line at a time your code
-await to see the outcome (button pressed...)

please acknowledge if the aforementioned steps are correct or i need something else.

I did execute your code with method i mentioned above and i cannot see anything on the console.
what am i doing wrong?

[OutoftheBOTS_]

Most people will usually write the code into a file with the extension on .py (e.g test_switch.py) then upload it to the board then import it (e.g import test_switch) but yes you can just paste it into the repl and this will run but you don't need to paste 1 line at a time just paste the whole script at once.

[atux_null]

thanks for your reply. as i mentioned above i do not see anything to happen in the console. is it something wrong with the setup?

[pythoncoder]

To paste the whole script press ctrl-e. The prompt will change as below

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>>> 
paste mode; Ctrl-C to cancel, Ctrl-D to finish
=== 

Then press ctrl-shift-v (if you're in a Linux console) to paste the code. Press ctrl-d to run it.

I agree with the comments of @OutoftheBOTS_ - the code isn't too clever - but it should work most of the time as the time spent in the 10ms delay will exceed that outside of it. So most switch changes will occur in that period. As I said, pasting it onto a Pyboard worked for me.

[OutoftheBOTS_]

maybe even start with something super simple to test to see if working

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import machine
import time
button = machine.Pin(12, machine.Pin.IN, machine.Pin.PULL_UP)

while True:    
	print (button.value)
	time.sleep(0.2)