The binary size impact is moderate, like 18 bytes plus
4 bytes per endstop defined.
The story is a follows:
The endstop logic can be used to use a touch probe with PCB
milling. Connect the (conductive) PCB surface to GND, the
spindle/mill bit to the signal line, turn the internal pullups
on and there you go.
However, doing so with pullups always enabled and while milling
under (conductive) water showed polished mill and drill bits to
become matte after a few hours of usage. Obviously, this small
0.5 mA current from the pullup resistors going through the
rotating mill bit is sufficient to get some spark erosion going.
That's bad, as spark erosion happening also means tools become
dull faster than neccessary.
With this patch, pullups are turned on while being used, only,
so this sparc erosion should go away.
This includes:
- Initialize them in mendel.c.
- While running, switch the pin only.
- Sort mendel.c the same order as in pinio.h.
- Remove the requirement of a parameter for this flag, like
it's with all other flags.
To INVERT an endstop, #define X_INVERT_MIN etc.
To leave it uninverted, define nothing, i.e. comment the #define out.
Probably, this change should be extended to INVERT_DIR and
INVERT_ENABLE, too.
The problem was, preprocessor flags are usually set with a simple
"#define X_INVERT_MIN", so X_INVERT_MIN is defined, but of
arbitrary value. Applies to other axes and INVERT_MAX also,
of course.
Initially, it was planned to allow "#define X_INVERT_MIN" as well
as "#define X_INVERT_MIN 0" but that turned out to be _really_
complex. See http://www.velocityreviews.com/forums/t720190-test-of-a-preprocessor-symbol-defined-as-nothing-vs-zero.html .
For curiosity, I've ported this to our purposes, debug messages
left in place:
#ifdef X_INVERT_MAX
#if CAT(1,X_INVERT_MAX) == 1
#warning "X enabled, inverted"
#define x_max() (READ(X_MAX_PIN)?0:1)
#elif X_INVERT_MAX
#warning "X enabled, inverted"
#define x_max() (READ(X_MAX_PIN)?0:1)
#else
#warning "X enabled, uninverted"
#define x_max() (READ(X_MAX_PIN)?1:0)
#endif
#else
#warning "X enabled, uninverted"
#define x_max() (READ(X_MAX_PIN)?1:0)
#endif
#warning "X disabled"
#define x_max() (0)
Markus Hitter
Bas Laarhoven
Michael Moon
Ben Jackson
Stephan Walter
Jacky2k
Markus Amsler