My arduino powered firework sequencer. This is gonna be a blast.

[usagi]

full details in the imgur album

[German_EE]

Ummmmm, yeah, all of that explosive material in one place, not good.

[CM800]

Ummmmm, yeah, all of that explosive material in one place, not good.

Uuuh, how do you think EVERY SHOP stores and displays them?

not a problem unless you're going about smoking next to them.

[Fungus]

Ummmmm, yeah, all of that explosive material in one place, not good.

[Fungus]

Nice build!

[T3sl4co1l]

Not really a platform for "mission-critical" applications like ignition.......

I hope you have a planned alternative method, whether it's hard wired ignitors, or dousing everything with water.

Not that these are the most dangerous pyrotechnics, just to be prepared.

Tim

[Fungus]

Not really a platform for "mission-critical" applications like ignition.......

Says who?

OK, the edge connectors on the Arduino Uno aren't great. I wouldn't use an Arduino Uno in anything critical but what's wrong with wires soldered into an Arduino Pro Mini (for example).

At the end of the day an Arduibo is just an AVR chip on a board and the AVR chip is perfectly suited to jobs like that. It has watchdogs, brown out detection, etc.

It's all the surrounding parts you have to be careful with and that applies to any chip. It's the design+software that counts.

[T3sl4co1l]

Says who?

OK, the edge connectors on the Arduino Uno aren't great. I wouldn't use an Arduino Uno in anything critical but what's wrong with wires soldered into an Arduino Pro Mini (for example).

At the end of the day an Arduibo is just an AVR chip on a board and the AVR chip is perfectly suited to jobs like that. It has watchdogs, brown out detection, etc.

It's all the surrounding parts you have to be careful with and that applies to any chip. It's the design+software that counts.

As you note, the Arduino board is just standard hardware, and, programmed responsibly (and hopefully, avoiding hardware bugs and errata in the chips?), that's fine.  I mean "Arduino" in spirit: if they're using the libraries.  Which are sketchy as hell...

(AFAIK, Arduino is supported on a lot more platforms than the official Arduino boards, so it's reasonable to associate "Arduino" more with the toolchain than just the boards.)

Tim

[NivagSwerdna]

How do you ignite each individual firework?

[SeanB]

Easy, just switch 12V to the ignitor with a Songle 3A relay. Relay will survive around 100 000 operation cycles typical in this application, which will be a pretty big number of bangs. The typical ignitor is not exactly sensitive, it needs a minimum of 1A of current to ignite, and typically will drop 1V across it in the short time it takes to blow. You really want higher voltage than 1V to ignite them, especially as the long thin disposable leads are going to drop quite a bit of voltage in that ignition time. Serious pro ignitors use a 10-50uF capacitor charged to 200-400VDC and a really heavy duty switch to do a really high pulse of current to initiate a load of ignitors all in series with thin cord, so that all will detonate before the thin cable vanishes in the blast.

[PartialDischarge]

Ummmmm, yeah, all of that explosive material in one place, not good.

At least he's doing it the right way. Electrically initiated pyrotechnics is the safest way to go.
Electricity isolates pyro stuff danger the same way optic devices isolates high voltage danger.

[Brumby]

Average citizens in NSW have access (legally) to only one form of firework - the sparkler. **

I think I would need to be extremely creative to get value out of that project.......


** That is now.  When I was growing up, we had common access to twopenny bungers (something similar in size to an 18650) and other explosive products of smaller sizes, Roman candles, Catherine wheels and a vast array of colourful display items.  Plus, there were skyrockets - from the fistful of a dozen for a shilling that just went fffffft and were gone in a second to the large bodied ones with a plastic nosecone that soared high and exploded in a glorious (for our pockets) display.

We also had a community bonfire in the park across the road.  It was not uncommon for it to be over 20 feet high ... and once the fire had burned down, people sat around toasting marshmallows over the embers.

I cannot remember how many years ago that was.......

[Syntax_Error]

What a bunch of poo-poo-ers, jeez.

Nice project, and looks ready just in time for my favorite holiday. Are you going to video your creation in action?

Have you thought about making a similar project for Christmas lights? They are getting pretty popular around where I live.

[NivagSwerdna]

I think it's really fun. (Do obviously be careful around explosives... I worked in an office once where someone was KILLED by a firework)

Anyway...

Are there techniques that need to be employed in the signalling... e.g. differential, current not voltage etc...  to stop the display being triggered by a passing taxi etc?

[Fungus]

Average citizens in NSW have access (legally) to only one form of firework - the sparkler. **

I live in the "City of Fire". There's firework shops everywhere and any excuse works. No birthday/wedding/funeral/Saints-day/whatever/etc. is complete without some fireworks. Any time of day is good: 3:00am? Not a problem.

Then there's the actual firework/fire festivals. There's days of the year when I can actually see the glass in my windows flexing because of the fireworks going off outside (no exaggeration) and aerial photos of the city look like the place is being firebombed.

This photo isn't a war zone, it's a party. 


note: This happens right in the middle of the city, narrow medieval streets and all. Some spaces are so tight you have to warn the fire brigade so they can come and supervise. This fireman isn't trying to put a fire out, he's just making sure nobody's house burns down.

[PartialDischarge]

I think it's really fun.

I live in the "City of Fire".

Come on say it, be proud, its Valencia, Spain. 

[Fungus]

I think it's really fun.

I live in the "City of Fire".

Come on say it, be proud, its Valencia, Spain. 

Getting back on topic (I forgot), there's a lot of demand for firework controllers around here.

[kolbep]

Just one thing to be careful of.
When most uC's are started up, their output registers can be in a random state.
Which means that even if you have the 1st few lines of your code set all the registers to 0, and their DDR to outputs, it may already be too late. The outputs could have already randomly fired at switch on.

One of the shows on TV was trying to find an effective way of braking a runaway truck trailer. They strapped remote control rockets onto it. But when the PyroTechnician went and turned on the receiver it did just that. Triggered the rockets which were facing their exhaust right at the cab door. He just managed to jump into the cab before turning into toast.

{Smash Lab S01E08
Runaway Trailer • 22:00 • Discovery  • 2008-02-27
The team investigates if you can stop a runaway trailer with truck using rockets. After testing 3 ways of using the rockets, a direct backwards-facing trailer-mounted system is used. A glitch in the firing system results in premature ignition, ending the experiment
}

[usagi]

Just one thing to be careful of.
When most uC's are started up, their output registers can be in a random state.
Which means that even if you have the 1st few lines of your code set all the registers to 0, and their DDR to outputs, it may already be too late. The outputs could have already randomly fired at switch on.

this is why 1) there's a "safe" mode switch, and 2) the mcp23017 has a reliable power-on-reset state.

[floobydust]

Looks like a lot of fun!

I've seen a system need an operator button press to OK advance to the next group, with an abort/stop button too.

If a firework does not ignite though, and your pulse widths looked narrow in the .gif, your software might need the ability to redo a bank?
Or it a big waterfall approach- one sequence only from start to finish?

[Fungus]

Just one thing to be careful of.
When most uC's are started up, their output registers can be in a random state.

Usually not 'random', usually it's high impedance (ie. INPUT with no pullup).

But ... if that's enough to set off the fireworks then you've already failed and shouldn't be allowed anywhere near anything explosive.

For fireworks you'd have a master relay for the 12V supply and only enable 12V power after all the Arduinos have woken up and reported their state to the master controller. Even then you'd have a second physical key on a string around your neck and only connect the 12V power a few seconds before the display is due to start.

[Fungus]

I've seen a system need an operator button press to OK advance to the next group, with an abort/stop button too.

I imagine they make it physically impossible for all fireworks to go off simultaneously in a large display. Banks of fireworks will only be enabled when previous banks have finished.

There'll be layers and layers of safeguards/redundancy/diagnostics. Plenty to keep an EE busy.

[usagi]

If a firework does not ignite though, and your pulse widths looked narrow in the .gif, your software might need the ability to redo a bank?

look at the scope image again. that's how long it takes for an igniter to blow open.

now tell me if the gif looks like it's that fast. 

[voltsandjolts]

Reminded me of this firework faux pa - everything went up in a minute. Oooops.
Be sure to remember all your semi-colons in the Arduino code, hehe 

[Fungus]

Reminded me of this firework faux pa - everything went up in a minute. Oooops.

How long was it supposed to last? Looks like an average display to me.