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A “pin” is an input or output on the Smoothieboard.
In a lot of cases ( step/direction for external stepper motors, button inputs ), you can use any pin for any use.
If other cases, a given pin is tied to a given peripheral on the board.
See Pinout to learn about which pins are where.
You can have a pin's output inverted by adding a “!” after this pin's number in the config line, example :
my_pin_name 19!
There are other modifiers for pins :
All options
! | Exclamation mark | Invert pin | ||||
o | Lowercase O letter | Set pin to open drain | ||||
^ | Caret, Shift+6 on QWERTY keyboards | Set pin to pull up (Default on most pins) | ||||
v | Lowercase v letter | Set pin to pull down | ||||
- | Minus sign | To set no pullup | ||||
@ | At / Arobase sign | To set repeater mode |