Helicopter animation using a Raspberry Pi

You could have a loop that runs at the flashing rate.

Each time through the loop decide which LEDs and functions are active or inactive based on the loop count.

Generally only the flashing LED will change each time through the loop, but after a certain number of loops each of the other functions will change state.

The flashing LED may flash between a start count and an end count.

Thanks Doug for the reply.

Help me understand you defintion of a loop? I have code that causes flashing. When I insert that code it runs once because my understanding of python is it is sequential. Step 1, step 2, step 3 and so forth. If step 2 is a loop that runs continious and the code advances to step 3 then a loop is what I think will work.

I thought step2 as a function but that didn't work. I thought step2 as a called module but that didn't work. Now forgive me when I say module. I import another python script. I have been trying to understand class objects hoping that might be the solution.

Can you provide a loop reference? When I research loops, i get the basic if then else return or while true.

Programming folks I have been put onto something called concurrency through threading or multiprocessing. I will continue to read but would appreciate someone pulling me back from the edge if I am heading in the wrong direction.

Here is a description of loops in Python:

https://www.learnpython.org/en/Loops

Assume your whole sequence takes the same time as 100 flashes, you would have a while loop that runs while count < 100

Inside the loop you can turn the flashing LED on if it is off else turn it off

If you want to turn cabin lights on at a count of 10 it is just another if statement inside the loop like if count > 10 turn on cabin led

if statement syntax can be found here:

ttps://www.tutorialspoint.com/python/python_if_else.htm

OK we are both on the same page when it comes to understanding loops. I wanted to make sure your loop and my loop were the same before proceeding with the discussion.

The turning on and then off of all lights is eight events. Four on and four offs. One of those events is a strobe. When the strobe is on, it is flashing. The whole sequence will occur over a specified time period. The whole eight event sequence is a loop.  That timing of the full loop will need to be refined as I integrate rotor animation and the sound. I'm estimating approx 2 minutes.

If the strobe was at the end of the sequence then I can see a loop working. Turn all three lights on, run the another loop to generate the strobe and then proceed to turn all three lights off. Restart sequence. Since the strobe is in the middle of turning on the lights, it needs to be a fire and forget. My thought is to have a start loop routine, then proceed with the other events and during the off sequence a stop loop routine.

I have been unable to separate the strobe to run independent from the other events. While the strobe loop is running the other two lights remain off. At least the way I have developed the code so far.

while True:

   #helicopter lights on sequence,cab_lit,stb_lit,pos_lit,lnd_lit
   GPIO.setup(cab_lit, GPIO.HIGH)

  time.sleep(3)

  objled_test.start() <--- this piece of the puzzle (strobe) needs to continue to run as the sequence of events continues. The code is an example of a failed attempt.

  GPIO.setup(pos_lit, GPIO.HIGH)

  time.sleep(3)

  GPIO.setup(lnd_lit, GPIO.HIGH)

  time.sleep(3)

   # helicopter lights off sequence,lnd_lit,pos_lit,stb_lit,cab_lit
   GPIO.setup(lnd_lit, GPIO.LOW)

  time.sleep(3)

  GPIO.setup(pos_lit, GPIO.LOW)

  time.sleep(3)

  objled_test.stop()

  GPIO.setup(cab_lit, GPIO.LOW)

  time.sleep(3)

Intergrated into this will be sound and motor control. I broke the animation into three components, light sound and motors. I'm working the light part now and add the others after that is equipped.

To calculate the number of loops in your while statement:

Suppose your strobe flashes 2 times per second (when it is flashing). In 2 minutes it would have flashed 240 times.

If it toggles on or off in each loop you would need 480 loops, with a 0.25 second delay at the end of each loop to make the 480 loops last 2 minutes.

Suppose you want the strobe to be flashing for 10 seconds at the 1 minute mark and off the rest of the time.

If the loop count is > 240 and < 280 then toggle the strobe LED on or off on each count else turn the strobe LED off

Suppose you want the cabin lights on after 10 seconds and off after 100 seconds.

If the count is > 40 and < 400 turn the cabin LEDs on else turn them off.

For any of/off event you just choose at which count it needs to happen and use an if statement to make it happen, even the strobe flashing on and off events..

What I think you need for flashing led2 is a timer routine.  In theory, when you wanted the LED2 to start flashing, you would clear a counter(if needed), and start the timer.  When the time expires (this could be you flashing rate) the timer routine would toggle the LED2 GPIO pin, reset the counter(if using), and exit.  Then when you wanted to stop the LED2 flashing, you would just have to stop the timer.  No threading or multiprocessing needed...

Thank for your input.

I have developed a routine that results in a LED2 flash that simulates a strobe. Varying the on and off times gives me the strobe effect I was looking for. When the routine is called, using my programming skills, the strobes either flash but the other LED's don't change or all the LEDs light up and nothing after that.

House  isolation gives me the time to keep programming. Keep the suggestions coming.

Try looking here for hints on how to use a timer:  https://www.geeksforgeeks.org/timer-objects-python/

Is this what you want to do:

LED1 on

LED2 start flashing

LED3 on, LED2 keep flashing

LED4 on, LED2 keep flashing

<time passess>LED2 keep flashing

LED4 off, LED2 keep flashing

LED3 off, LED2 keep flashing

LED2 off, LED2 stop flashing

LED1 off, LED2 still off

repeat...

Probably, this is the most elegant and efficient solution. The possible alternative I see is managing interrupts chained so every state set to a different state in the others but this is tricky and not interesting in this case. A real alternative, instead, at least in my opinion, is creating a dictionary in Python collecting every change in a different boolean variable. Then a single function will set/reset the LEDs on/off as well as the motor, sound, and any other part that should be included in the animation. This optimizes the code and makes easier to change the pattern of the animation.

In the main infinite cycle while true if using a json file with different animation patterns these can be randomly looped to get a more interesting effect.

Enrico