NameError: name 'timers' isn't defined

[mdibit]

To whom is reading this post : this program is just a simplified exercise to better understand the strange behavior of my original program where the thread Semaforo should be substituted by a robot code which should receive command from web app.
So :
The error generated by the code:
Unhandled exception in thread started by <function thread_Semaforo at 0x20015d80>
Traceback (most recent call last):
File "", line 91, in thread_Semaforo
File "", line 44, in timerWait
File "", line 34, in timerAttivo
NameError: name 'timers' isn't defined

I'd like to understand why, in the following code, I get the error only if the function generating the error is called from the thread Semaforo but it's perfectly working if called from the main program (or main thread).
What is even more strange is that, in the same function, the error is generated after the same name has been used before.
Thanks
Michele

import network
import socket
import time
import random
from machine import Pin
import _thread

TEMPO_STOP = 2**31
global timers
timers = [TEMPO_STOP,TEMPO_STOP,TEMPO_STOP,TEMPO_STOP,TEMPO_STOP,TEMPO_STOP]
global T_1
T_1 = 1 # timer 1

Create an LED object on pin 'LED'

led = Pin('LED', Pin.OUT)

Wi-Fi credentials

ssid = 'YYYYYYY'
password = 'XXXXXXXX'

pulsantePremuto = False

def timerStart(timer, durata):
global timers
timers[timer] = time.ticks_add(time.ticks_ms(),durata)

def timerStop(timer):
global timers, TEMPO_STOP
timers[timer] = TEMPO_STOP

def timerAttivo(timer):
global timers, TEMPO_STOP
return (timers[timer] != TEMPO_STOP)

def timerScaduto(timer):
global timers
return ((time.ticks_ms() > timers[timer]) and timerAttivo(timer))

def timerWait(durata):
global T_1
timerStart(T_1, durata)
while ( timerAttivo(T_1)):
pass
timerStop(T_1)

HTML template for the webpage

def webpage(random_value, state):
html = f"""



<title>Pico Web Server</title>

Raspberry Pi Pico Web Server

Led Control

LED state: {state}

Fetch New Value

Fetched value: {random_value}

"""
return str(html)

def thread_Semaforo():
global pulsantePremuto
global T_1
while (True):
print("Rosso")
if pulsantePremuto == True:
for i in range(10):
led.value(1)
print("ON",i)
timerWait(1000)
led.value(0)
print("OFF",i)
timerWait(1000)
#pulsantePremuto = False
timerWait(5000)
print("Verde")
timerWait(5000)
print("Giallo")
timerWait(2000)

#-------------------------------------------------------------------------------------

_thread.start_new_thread(thread_Semaforo, ())

print("Connect to WLAN")
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(ssid, password)

Wait for Wi-Fi connection

connection_timeout = 10
while connection_timeout > 0:
if wlan.status() >= 3:
break
connection_timeout -= 1
print('Waiting for Wi-Fi connection...')
time.sleep(1)

Check if connection is successful

if wlan.status() != 3:
raise RuntimeError('Failed to establish a network connection')
else:
print('Connection successful!')
network_info = wlan.ifconfig()
print('IP address:', network_info[0])

Set up socket and start listening

addr = socket.getaddrinfo('0.0.0.0', 80)[0][-1]
s = socket.socket()
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(addr)
s.listen()

print('Listening on', addr)

Initialize variables

state = "OFF"
random_value = 0

Main loop to listen for connections

while True:
try:
print("qui")
conn, addr = s.accept()
print('Got a connection from', addr)

    # Receive and parse the request
    request = conn.recv(1024)
    request = str(request)
    print('Request content = %s' % request)

    try:
        request = request.split()[1]
        print('Request:', request)
    except IndexError:
        pass
    
    # Process the request and update variables
    if request == '/lighton?':
        print("LED on")
        led.value(1)
        state = "ON"
    elif request == '/lightoff?':
        led.value(0)
        state = 'OFF'
        pulsantePremuto = False
    elif request == '/value?':
        random_value = random.randint(0, 20)
        pulsantePremuto = True

    # Generate HTML response
    response = webpage(random_value, state)  

    # Send the HTTP response and close the connection
    conn.send('HTTP/1.0 200 OK\r\nContent-type: text/html\r\n\r\n')
    conn.send(response)
    conn.close()
    print("qua")

except OSError as e:
    conn.close()
    print('Connection closed')

[mdibit]

I'm sorry for the code not well indented, I'll try to get it better (maybe with mark down)

[robert-hh]

See the instructions. For code use lines with triple backticks before and below the code.