i have a board with atmega2560 processor, i need to use a limit switch (endstop button) i tried to connect with 5v and read like pinMode(10, INPUT); digitalRead(10); but cable is 1m length and it act like antena (floating) so randomly get high and low I saw few articles that i need to use pu…

[image] arpa123: does atmega2560 has internal pullup resistor on all pins Read the data sheet.

ATmega2560 microcontroller has internal pull-up resistors. The microcontroller has programmable pull-up resistors that can be enabled or disabled on its digital input/output pins using software. To enable the internal pull-up resistor on a specific pin, you can set the corresponding bit in the PORT…

Using an external 5.1K pull-up might save you future headaches due to unforeseen circumstances.

For longish wires, a stronger (smaller value external resistor) can be used as a pull up. See switch S2. [SwitchesAndLEDs] You can also add a 100nF capacitor from the input pin to GND.

[image] jim-p: Using an external 5.1K pull-up might save you future headaches due to unforeseen circumstances. i hake 4.7K resistor is that ok?

INPUT_PULLUP atmega2560

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paulpaulson April 14, 2023, 2:34pm 2

Read the data sheet.

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INPUT_PULLUP atmega2560

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