[TriEmbed] IR sensor vs trigger

[Jon Wolfe]

I agree with the others, it sounds like the trigger should get the interrupt.

Like Jeff said, you want your interrupt to execute in as short of a time as possible. One approach might be to just set a flag on trigger presses then process the action in the main loop. That could still leave you with 1 sec latency if you are detecting IR hits, which would probably be pretty noticeable.

I have never tried this on a tiny, but I'm making it a personal mission to find a use case for it, but you could use an RTOS, like http://www.femtoos.org/  Looks promising. I've used ChibiOS on Cortex M3/4's and found it pretty nice to work with, YMMV. 


The other alternative approaches might be to try to reduce the 1 second detection loop. Or, to try to architect your own "cooperative multitasking" or coroutines. In short, write your detect loop so that instead of looping for 1 second, it just does a little bit of work and returns to the main loop, remembering where is was in the loop between each call. I use this approach a lot.

I will say that you should try to handle debouncing the trigger in hardware as much as you can. I've tried software debouncing mechanical encoders in interrupt driven routines, and I can attest that it is maddening.

Lastly, you *could* always just buy a separate tiny for the detection, but I have no ulterior motive or bias there ;)





________________________________
 From: Joe Fair <joe at fairanswers.com>
To: triembed at triembed.org 
Sent: Saturday, July 26, 2014 4:09 PM
Subject: [TriEmbed] IR sensor vs trigger
 


Ok.  I'm pretty close on getting my home made laser tag with at tiny 85s going, but now i have a question about design.
The loop I'm using detects a trigger pull, then a hit on the sensors.  however, The pulse in function I'm using to sense IR ha a timeout of 1 second.  If there is no inbound signal it is only checking got a trigger pull once a second.
So i need to use an interrupt, but does it matter if i use one on the trigger pull or the ir sensor? 
Joe

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