Update README.md #60
Update README.md #60
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Usually NC are connected from high voltage to the NC switch, then to the Input of a controll unit. For Microcontroller you need to wire it towards ground. This should help people to understand that better.
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This is a tad more complicated and depends on the configuration. Both NC and NO switches may be wired to the +ve supply. The pullup resistors can be turned off by $18 (this will enable pulldown instead for most, if not all, drivers) and the inputs inverted by $15.
It is also possible to wire limit switches (with three terminals) to GND, the +ve supply and the inputs.
Relying only on the internal microcontroller weak pullup (or pulldown) resistor only for a board design is, IMO, bad practice. Typically these are around 50 K, with a 3.3V +ve supply the current provided could be below the switch wetting current? A capacitor and/or a lower value pullup/pulldown resistor should be added to the circuit - both for provinding enough current and improve noise immunity. Even better is to use optocouplers (some boards do) - this will increase the switch current, provide better noise immunity (since most are acting as a low-pass filter) and provide protection for the microprocessor pins.
IMO the sentence should be written a bit differently to take this into account.
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Understood, I was just focusing on the struggle I had. It is described pretty well with your explanation and the regular grbl wiki. I will see that I get something together from your answer and the grbl wiki fitting for grblHAL. |
Usually NC are connected from high voltage to the NC switch, then to the Input of a controll unit. For Microcontroller you need to wire them towards ground. This should help people to understand that better.