Home 2018 Forums Crumble Development Proximity and PIR Crumb sensors seem temperamental Reply To: Proximity and PIR Crumb sensors seem temperamental


Just for info – I’ll post the advice I got from 4tronix below. Maybe it was just too much Sun… I’ll investigate in a darker environment…

Response from 4tronix…

“Proximity crumb. This is a very simple device and should be consistent, in a consistent environment. It sends a constant IR signal and simply activates if it gets a strong enough incident IR light. The problem can be that sunlight (and some office/school lights) can provide enough signal for it to trigger even without a reflection. This is a real problem with a lot of static IR sensors like this. It is best to use these away from direct sunlight/windows and bright lights.

PIR crumb. The PIR module used on the crumb operates by detecting a change in the incident IR levels. So unlike the proximity crumb, it isn’t the absolute level that triggers it, but the rate of change of the incident brightness. Of course, similar problems can cause it to trigger as it is a fairly simple device in truth. It also has 2 trimmers on it which you may want to adjust. One sets the sensitivity and the other sets the delay time. Different modules will probably have these set to slightly different positions, causing different behaviour. To test them when I’ve built them. I turn them on, walk away 3 or 4 yards/metres, count to 15 while standing still, then walk back to the desk with them on. This has always worked fine for me.”