OptrexLCD (OptrexLCD.h)

These are super cheap 4 digit displays, with no decimal points, and the words "CLEAR" and/or "SECURE". They must have been made for a security alarm. These are not smart, and must be continually refreshed (supplied software driver does this). They can be purchased as surplus for as little as $1.95. This software requires the use of library MsTimer2.