Intermittent issue - Interrupt being triggered in error

I have built and deployed a number of pressure sensors in local parks. As the size of the deployment has grown, I have started to see an issue come up infrequently which I suspect has to do with an electrical issue. I have a custom sensor based on an Arduino which sends an active high trigger when a pressure event is detected. That line is connected through a 1.5" un-shielded wire directly to the Electron’s B1 pin which is configured as an input. I have also selected this pin as an interrupt on the RISING edge.

Is there more I need to do to condition or filter this line? Could there be cross-talk between the wires connecting the board and the antenna for the Electron? Do I need to add a Schmidt trigger on the input to introduce hysteresis?

Any advice would be appreciated.

Thanks, Chip

Is your sensor providing a discrete level for both states (triggered/untriggered)?
If not, you may need to add a stronger pull-down.

Shielding and filtering is nevere wrong :wink:


The sensor is analog so, I have a small ATTiny on the breakout board which sends a pin HIGH once the sensor passes a certain threshold. It then hold the interrupt line high for 100mSec and brings it back low. I also have a pin I could use to manually reset the interrupt line but, have not used it. Since that ATTiny is either sending digitalWrite HIGH or LOW and I force it to wait before it can change state, I was hoping to eliminate bounce and avoid having to use PULL_DOWN on the Particle Interrupt pin.

If you or anyone else knows of a good reference on filtering and shielding - particularly with lines used to trigger interrupts, I would appreciate a link.

Thank you, Chip