Duet 3 MB6HC - IO Pin Capabilities

[TechNi]

I am designing a customized PCB with a NC microswitch (limit switch) which will be connected later to the IO Pin of the Duet 3 and used as axis endstop. Hence, a few questions:

1. As per the documentation, a simple 2-wire microswitch should be connected to the IN and GND pins of the IO connector. Is this 3.3V or 5.0V? Because I wish to connect an LED in series for switch feedback and need to pick an adequate resistor.

2. In addition to the microswitch and the LED mentioned above, the PCB has another brighter LED which should illuminate the scene a little bit. Is it somehow possible to turn this LED on/off using the IO connector? I know this would work with a fan connector but with an IO?

Thanks in advance.

[dc42]

1. The IO_IN pins are safe up to 30V and require a minimum input of about 0.9V for logic low and 2.4V for logic high. They have built-in 27K pullup resistors to +3.3V. I suggest you connect your LED + series resistor between the input and +5V.

2. The IO_OUT pins have a 470R series resistor to protect them, so not suitable for driving high brightness LEDs. I suggest you use a small mosfet or NPN transistor on your board to drive the LED from an IO_OUT pin.

[TechNi]

Nevermind...