Power up without doing Repl changes program behaviour

[ADenislebel]

I wrote a simple timer program to turn on a light at a given time
and turn is off at a later time. When connected with Thonny the
program runs fine. However when disconnecting and powering
up the pico from a separate 5 volt source the program runs
as confirmed by flashing the onboard led but fails to initialize
the light output set in the first few lines of the code. I tried adding
a machine.reset() as the first line of the code but the symptoms
remain the same.
Program listing below unable to use the attach feature

Timer program

setup 1 minute timer

import machine
import utime
from machine import Timer,Pin

On_tm = 6 # on time @ 6 am
Off_tm = 19 # off time @ 18 pm
Hour = 6 # start hour
Minute = 0 # start minute
Sec = 0 # seconds
Alt_flg = True # altrnate action flag
Led_stat = False # led status chng flag
Min_flg = False # minute turn over flag
Led_io = Pin(25,Pin.OUT) # onboard led
Lit_io = Pin(1,Pin.OUT) # relay is on GPIO 0

update timer callback routine every second

def Upd_timer(t):
global Minute,Hour,Sec # re-use same
global Led_stat,Min_flg # variables

Sec += 1				# update sec				
Led_stat = True			# set led flag
if Sec is 60:			# chk sec turn over
    Min_flg = True		# set min flag
    Sec = 0				# clear seconds
    Minute += 1			# incrmt minute
    if Minute is 60:	# chk min turn over
        Minute = 0 		# clear minute
        Hour += 1		# update hour
        if Hour is 24:	# chk hour turn over
            Hour = 0	# clear hour
pass                    

main starts here

Led_io.on()
utime.sleep(2)
#machine.reset()

Sec_tmr=Timer(period=1000,mode=Timer.PERIODIC, callback=Upd_timer)
print('Start Time:',Hour,Minute) # show start time
if Hour >= 6 and Hour < 19: # check on time limits
Lit_io.on() # light on
while True: # run forever
if Hour is On_tm: # is it 6 Am
Lit_io.on() # light goes on
if Hour is Off_tm: # is it 19 PM
Lit_io.off() # light goes off
if Min_flg is True: # chk min flag
print('Time Hr,Min:',Hour,Minute) # show time
Min_flg = False # clr min flag
if Led_stat is True: # chk led status
if Alt_flg is True: # chk alt flag
Led_io.on() # led on
Alt_flg = False # chng flag
else : # or
Led_io.off() # led off
Alt_flg = True # chng flag
Led_stat = False # clear status
utime.sleep_ms(500) # no rush pause

[ADenislebel]

Also tried a machine.soft_reset() as well on entry, did work either

[ADenislebel]

Found the problem. I needed to rename my the timer program to main.py as Thonny simply
reloads the program with its current name to the Pico. However the pico boot up process
only looks for a main.py. In my case I had tried before a blink program that remained on
the pico as main.py. Since my program also flash the led at the same rate it seemed like it was
running when in fact it was the old blink program. When your green you don't see that
shit coming. Hope this might help other newbies with the pico.
Thanks anyway Denis

[peterhinch]

In general it's best not to rename your program. When you're ready to deploy, edit main.py to start the program. That way, if you need to edit the program, you can simply comment-out the line in main.py and run it at the REPL.