The requirement was simply neither obvious nor intuitive. Drawback
is, the indices of temperature sensors can now differ from these
of the heaters. That's easier to recognize for newbies, though.
This is not only handy for debugging non-PWM mode, it may also
help those who run a heated bed attached to a solid state relay.
This way it was found out connecting heaters to non-PWM pins
works just fine and did so for a loooong time.
Not yet distributed to all the config.h templates.
Now we don't have tables for default or gen7 electronics, but
two default tables for a single vs. two different thermistors.
This seems to be more logical.
This is a intrusive patch and for now, it's done for the X axis only.
To make comparison with the former approach easier ...
The advantages of this change:
- Converting from mm to steps in gcode_parse.c and back in dda.c
wastes cycles and accuracy.
- In dda.c, UM_PER_STEP simply goes away, so distance calculations
work now with STEPS_PER_MM > 500 just fine. 1/16 microstepping
on threaded rods (Z axis) becomes possible.
- Distance calculations (feedrate, acceleration, ...) become much
simpler.
- A wide range of STEPS_PER_M can now be handled at reasonable
(4 decimal digit) accuracy with a simple macro. Formerly,
we were limited to 500 steps/mm, now we can do 4'096 steps/mm
and could easily raise this another digit.
Disadvantages:
- STEPS_PER_MM is gone in config.h, using STEPS_PER_M is required,
because the preprocessor refuses to compare numbers with decimal
points in them.
- The DDA has to store the position in steps anyways to avoid
rounding errors.