Help with figuring out electronic/digital input value
I got this CO2 sensor which can be forced to calibrate with a digital input to one of its pins. I'm trying to figure out what is the safe way of doing that: The document states the need for a Digital Input "when closed for minimum 4 seconds"
I'm not sure if I can just short this pin to another PWM 1kHz output pin for 4 seconds to trigger calibration.
Can anyone help me validate this? the pin is "bCAL_in/ CAL" and the info is on top of page 5 of this doc http://www.senseair.co