EMC uses 'nist-logic' for most IO, meaning there is one on-switch/signal to switch a thing on, one off-switch/signal to switch it off, and one indicator-signal to tell you the state.
To connect momentary-on pushbuttons to EMC you need at least the toggle component, but I've found that it doesn't work that great with things that can be set/reset by other parts of EMC. For example the coolant state might be set from the AXIS checkbox, G-code, MDI, a pyVCP button, or a hardware button through halui.
I made toggle2nist to set the coolant state with a momentary-on pushbutton. The hardware button connects to a toggle, and the toggle output connects to toggle2nist. It also needs the is-on signal, and produces as outputs the on/off signals (to halui.flood.on and halui.flood.off in this case).
component toggle2nist "toggle button to nist logic";
pin in bit in;
pin in bit is_on;
pin out bit on;
pin out bit off;
variable int old_in;
variable int to_state=0;
function _;
license "GPL";
;;
FUNCTION(_) {
if (in!=old_in) /* a toggle has occurred */ {
if (is_on) { /* turn OFF if it's on */
on=0;
off=1;
to_state=0;
}
else if (!is_on) { /* turn ON if it's off */
on=1;
off=0;
to_state=1;
}
}
else {
/* reset pins when we see the desired state */
if (to_state==is_on) {
on=0;
off=0;
}
}
old_in=in;
}