Scale extruder motor current linearly with speed.
49% less heating when running at low speed and standstill, 4% more torque at maximum extrusion rate (15mm^3/s), 15% more torque in high speed movements (un/retractions).
StealthChop mode is used for low speeds (below 900mm/min)
spreadCycle is used above. Transition speed is well above maximum extrusion rate of 15mm^3/s (275mm/min) so mode transition is not expected to be visible on printed surface.
StealthChop is expected to improve printed surface quality (less artifacts).
Warning you can burn extruder motor if it is not the same impedance as original Prusa i3 Extruder stepper motor. There is no current feedback in low speed so lower impedance motor can be burned by over current.
Even there is no direct current feedback, there is no risk for original motor thermal runaway, as motor resistance increases with temperature, current decreases.
Standstill peak phase current is expected to be 500 mA and linearly increase with speed to 970 mA at 900mm/min where spreadCycle constant current regulation takes over and keeps peak current at 805 mA to maximum speed possible.
As motor heating increases with current squared, lowering low speed current from 700mA to 500mA decreases heating 49% in thate mode, where motor spends most of the time.
Enable E-motor cool mode in farm mode only (and experimental menu) - the experimental menu is visible AND the EEPROM_ECOOL variable has a value of the universal answer to all problems of the universe - i.e. two conditions must be met at the start of the FW to enable the E-cool mode. If the user enables the experimental menu, sets the E-cool mode and disables the menu afterwards, on the next start of the FW the E-cool mode will be DISABLED. This is still subject to discussion how much obscure (security through obscurity) we'd like this option to have .
Additional stuff:
* Add serial debug msg to verify if E-cool mode is on
* Avoid access to E-cool mode switch on machines without TMC2130
* Do not allow only M907 E in case of E-cool mode+warn the user on the serial line that the command was skipped
Co-authored-by: D.R.racer <drracer@drracer.eu>
gcode_M600_filament_change_z_shift is almost useless, since it performs
what is already been done internally by filament_unload().
However it *does* cause the carriage to raise earlier during unload
compared to making the user wait after "press for unload".
Change it so the calculated Z height matches MIN_Z_FOR_SWAP.
This change restores the minimum extruder height for filament purge
during M600 from the current 50mm back to 27mm from FW 3.9.
We do this by introducing a new option for unload_filament() to indicate
that the unload is part of an automatic swap, and in such cases avoid
raising more than absolutely necessary (this will _also_ come in handy
to avoid the extra purge in PR #2318 during M600).
A new define MIN_Z_FOR_SWAP is introduced for this purpose.
MIN_Z_FOR_UNLOAD is still used for manual lcd unload and for M702 and
hasn't been changed.
If the printer was already being pre-heated but didn't reach the target
temperature yet and a new filament is being inserted, the LCD used to
display a "Preheating to load" message to block the loading until the
extruder is hot.
This message is currently missing, and the ">Cancel" option doesn't
display immediately either, depending on the extruder height.
This PR fixes this behavior, which was broken during an earlier update.
We now force-update LCD updates during the first (and _only_) time the
screen is setup, and push all messages _before_ the carriage is
eventually raised, so that ">Cancel" is shown immediately as well.
