Investigate creating a single voltage version of the LEK MorseKOB Loop Interface

[AESilky]

The current MorseKOB Loop Interface uses a dual-voltage LM741 Op-Amp in order to connect to an RS-232 computer port (+/- 3V to +/- 15V Mark/Space levels).

It is anticipated that many Device-In-A-Box client-interface implementations will connect to an MPU through a GPIO interface. Therefore, there isn't a need for a dual supply. So maybe a single supply Op-Amp or Voltage Comparator (like a LM393) can be used to eliminate the need for a dual (+/-) power supply and additional interface components needed to connect to the 3.3V or 5.0V GPIO MPU interface.

This issue is to investigate/research options, review options with the team, and possibly prototype an implementation.

[AESilky]

@leskerr @pwdirks I wanted to create a repo that we can use to collect our information about creating an Interface Device-In-A-Box (iDIAB). That can include circuit diagrams, code to implement them, notes, documentation, etc.