I was wondering about a simple tutorial on setting up a triggered stopwatch with a 555

I was wondering how it would be possible to hook up a 555 as a timer for the photon. It was recommended to me to use the 555 and not the internal timing on the unit itself?

The 555 is a bit above my comfort level as of now.

I want as the endgame to have a triggered stopwatch(trigger to be determined) and accurate timing when an accelerometer is impacted. So report back the interval between the trigger and accelerometer. I would need it to be resetable and would also need to get “lap” timing as well. So just not a beginning and end time of the event. The accelerometer would be tapped a few times before the “end” tap.


@bostonmacosx, why do you believe you need a 555 to achieve what you are looking to do? How long an interval (trigger to accelerometer) are you considering? A 555 doesn’t “report back” anything except possibly a pulse representing the time between the start and the end events. If you can give a few more details, we may be able to give you better guidance. :grinning:

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Thanks for looking in on this thread. I always appreciate help where I can get it.

The short of it is thing shuttle run over a long period of time.

So lets say a wifi-signal starts the “timer”. The when the accelerometer is “thwaped”(batman term) it would figure out the time and report it into a text file or back to somewhere online or wherever. It would continue running and then when “thawped” again it would record the time again.

After a certain amount of “thwaps” it would consider it the end of the race and just stop timing and reset for the next race.

The person I spoke to breifly said if there was an interrupt or something on the Photon itself that it could effect the timing. This is above my level of understanding currently. I currently turn on and off LED lights and am understanding circuits basically. I’m coming from more of a web design/programming background and have stumbled upon this cool world.

I have an endgame “real” product I’m hoping to develop and these are baby steps into that endgame.


[quote=“bostonmacosx, post:3, topic:19761”]
The person I spoke to breifly said if there was an interrupt or something on the Photon itself that it could effect the timing.
[/quote]I think you source needs to be “thwapped”! Just kidding!

How much time do you expect between each event? The Photon is FULL of interrupts but that doesn’t mean you can’t achieve what your looking for. If you are looking for microsecond timing between events with an accuracy of 1us then you may have an issue. However, I suspect that is not what you need. Can you please elaborate?

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I’m looking for 100th of a second accuracy over about 15 seconds to about 9 minutes…a “lap” will occurr about every 30 second or so.

@bostonmacosx, the Photon can handle that easily without need for a 555!

i think the limiting factor would be the accelerometer and wifi timing not the timing/interrupts. how many samples/sec will you get with the sensor your using + calculations required to determine a “thwap”. also wifi isnt instant… maybe UDP would be the way to go for speed, but there may have to be a fudge factor added to compensate that too.