Duet functional with <= 6VDC?
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I'm trying to sort out an idea in my head and was wondering if a duet board would be able to do much of anything if VIN is <= 6VDC. Specifically, could it do anything with any attached extruders, heaters, fans, or anything else "plugged in" to the duet board?
My motive for asking is that I'm thinking of the idea of having DWC and/or Paneldue act in a limited function while VIN is lower than a given threshold. In that limited mode, the "movement" and "extruder" buttons would be hidden/disabled, as well as anything else that would require a "heater", "fan" or "extruder." In place of those buttons would be some indication that power is turned off. However, macros and gcode printering would still be available (as either might call M80.)
This came about because my wife (who I love dearly, but isn't the most technologically advanced person) called me up today asking me to help her figure out why the 3d printer wasn't working… and the only reason was that the primary PSU was turned off. (The duet board is powered via it's own 5VDC going into the microUSB port.)
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The stepper drivers need at least 9V. The firmware will refuse to drive them if the measured VIN voltage is below 9.5V. The heaters and fans are normally powered from VIN too. But the firmware can respond to status requests etc. from USB/PanelDue/DWC etc. and report temperatures with just 5V power.
I guess there should be some error messages produced if you attempt movement when VIN is below 9.5V. I'll make a note to add this to the next release.
