Connecter les capteurs de fin de course

Détecter une position, Electronique de commande

The endstop are use for the machine can have reference point, machine origin “0”

For endstop it’s common to use SPDT switch (Single Pole Double Throw) more information here










In the official smoothieboard endstop documentation
have this drawing  and it’s write   “Wiring a basic NC endstop

And when you see your smoothieboard , you can guest when endstop is hit the “O Volt” go to the Signal pin


If you beginner to wiring endstop in input of microcontroler may be you ask at yoursef two question.

– Why use only 2 wire and don’t use 3 wires Ground (-)   Signal and VCC (+) ?

  • Why the information “O” is send tu input of microcontroller and not “+” ?

The answer or there question are not specific for smoothieboard, the technology use is same when connect switch SPDT or pushbutton in input of electronicboard ( arduino, 3d printer board, etc … )


Why use only 2 wire and don’t use 3 wires Ground (-)   Signal and VCC (+) ?


Use 3 wire is Ok, it’s works
– when endstop push, the signal pin of électronic card receive 5Volt to send information “endstop push”

– when endstop don’t hit, the signal pin of électronic receive
0 Volt to send information ‘endstop don’t hit

It’s works, just have 3 small disadvantage

  • need buy and prepare more 3 wires if you  connect xmin ymin and 7min. 6wires more if you connect endstop min and end stop max.
    A little more money and time to prepare
  • If the red wire (+) breakdown the machine continu to more over the endstop. If the machine is small without very big motor, not damage, but with heavy and strong CNC professional, a simple wire breakdown can be cost a lot of money with damage result.
  • If you whant connect a touch plate in Zmin, only have 2 location tu connect can’t use the 3 wire.







What need to know when use only 2 wire for connect switch or push button to microcontroler board ?

Below à explain of James Lewis the creator of and youtube chanel

A pin of input microcontroler board can’t unconnect. If you do this the interference around create sometimes 4,8V; 0,15V 5V…  and create fake information inside.   That’s why in the video sometimes the LED don’t blink when push button and sometimes blink without push buton. Have somethinks out of control.

The pull up resistor solution explain by James Lewis

Support this guy with buy his DVD if you whant learn électronic because he’s explains are very good