A method can be used for channel mapping based on frequency hopping. In advance of the start of a slot as may, for example, be indicated by a signal from, for example, a slot timer, a state machine may schedule the function that will be permitted to interrupt a processor. A photodiode with a shallow doping profile with respect to the top surface of a substrate and a graded pinned surface layer, self-aligned to a gate stack is provided. Alternatively they may be fibers having a piezoresistive property and the changes in resistance may be monitored. A micro-porous membrane filter having a pore size smaller than 10 um is employed to cover the vent so as to reduce the flow of contaminants into the camera module.