First of all, that suggestion worked! But, added to my task not...and so I guess that there is something I am missing. I have the script that starts with:

def run_start():
hw.LED.on()
hw.oephys_TRG.on()
hw.mic_TRG.on()
set_timer('session_timer', v.session_duration)

with this definition I aim to start recording in oephys, start recording of usvs and light on the led (that I can see in the video to synch the start task). The script continues with:

def init_trial(event):
if event == 'entry':
hw.LED.off()
v.trial_number += 1
print('Trial number: {}'.format(v.trial_number))
timed_goto_state('reward_delivery', v.delay_to_reward[v.delay_index])
v.delay_index += 1
elif event == 'external_poke_IN':
v.external_poke += 1
goto_state('reward_delivery')

and the def after I will switch on the LED, for this reason in the state initial trial i need the LED off.

How can I get the first led on ( when I run start) on for a time that it is visible to the camera? Because if add your suggestion to my script..I have always the same problem because in the state initial_trial the led is off.

Do you want the LED on for a couple seconds at the start of the session, and then turn off the LED as the trials begin?

You could add an intermediate state, something like this?

events =["sync_done",'external_poke_IN']
states = ["video_sync","init_trial","reward_delivery"]

initial_state = "video_sync"

v.startup_LED_duration = 5 * second 

def run_start():
    hw.LED.on()
    set_timer('sync_done', v.startup_LED_duration)
    
def video_sync():
    if event == "sync_done":
        hw.LED.off()
        goto_state("init_trial")


def init_trial(event):
    if event == 'entry':
        hw.LED.off()
        v.trial_number += 1
        print('Trial number: {}'.format(v.trial_number))
        timed_goto_state('reward_delivery', v.delay_to_reward[v.delay_index])
        v.delay_index += 1
    elif event == 'external_poke_IN':
        v.external_poke += 1
        goto_state('reward_delivery')

def reward_delivery(event):
    #reward delivery code here

Sorry if I'm still not understanding your request. If that isn't what you are asking for, please let us know.

If you can add your task code in your response that would be helpful. When pasting, first add three backticks, then python and then on the next line(s) add the code, and then a final line of three backticks like this:

```python
paste your code here in between the backticks
```