Prusa Filament Out Sensor

12/30/17 Update
This part supports Filament Out sensing directly by the Prusa Mini-Rambo 1.3a board. See section below for implementation. Please note this requires a non-standard firmware load. This far I have not found any item supported by Prusa 3.1.0 firmware that this modified firmware does not support as well. This has the advantage of supporting Filament Out sensing when printing from the SD card as well as OctoPrint.

This Prusa i3 MK2(S) Filament Run Out Sensor detects filament exhaustion and triggers a Filament Change using M600 command. After the filament is changed, printing is resumed at the point of interruption.

This design depends on Octoprint to process the Pause, Filament Change, and Resume commands. Other applications could utilize this accessory as long as they rely on GPIO4 (Board Pin 7) to signal Filament exhaustion.