First, Do No Harm . All of us who design multi- function devices should consider their functions separate. A problem with one subsystem should never create problems with another.

Cummins Centinel. Managing the addition of oil to a diesel engine's fuel-oil mix turns out to be a tricky problem. Here's one design that worked well.

Debug Tip: Circular History Buffer .It is often useful to examine the sequence of events leading up to an observed software anomaly.Here's a handy way to capture events of interest to RAM.