FezCNC

[Brett]

it sure could.

To slow down the transitions you could always use a capacitor - forming a simple RC filter.

Another easy way to make sure it’s not the vibration is to disconnect the switches

[Unknown]

@ Brett, so that would be just a 47uf capacitor across the switch and GND right?

[GMod_Errol]

That is way too big. You need 100nF or there about. Are you sure you enabled the pullup on the pin?

You might be better off to add a 10K pullup resistor beterrn every switch pin and 3V3.

[Unknown]

@ Errorl, yes I’m sure I enabled the pull up. 100nF or a 10K pull up?

[GMod_Errol]

Both…

The pullup helps immunity against noise.

The 100nf helps block noise.

[mhectorgato]

@GMod(Errol)

That is way too big. You need 100nF or there about. Are you sure you enabled the pullup on the pin?

You might be better off to add a 10K pullup resistor beterrn every switch pin and 3V3.

For my own electronic learning: Would a larger capacitor (like the 47uF mentioned) cause problems? Or is it just overkill for this application?

[GMod_Errol]

The capacitor and pullup resistor forms a RC filter. The time constant is proportional to the capacitor size and proportional to the resistor size.

This just means that the RC filter adds a delay to the circuit, the larger the capacitor, the longer the delay, the larger the resistor the larger the delay.

For a 47uf capacitor you will have to make the resistor REALLY small, 10 to 100 ohms, to get a decent response time.

If I did the math correctly then a 10k resistor and a 100nf resistor filters the same as a 21 ohm resistor and a 47uf capacitor. The problem is that the 21 ohm resistor will draw 157mA when the switch is closed, which is a problem.

Edit:
Looked at the formulas again, R is proportional, not inverse proportional…

[mhectorgato]

@GMod(Errol)

The capacitor and pullup resistor forms a RC filter. The time constant is perportional to the capacitor size and inverse perportional to the resistor size.

This just means that the RC filter adds a delay to the circuit, the larger the capacitor, the longer the delay, the smaller the resistor the shorter the delay.

For a 47uf capacitor you will have to make the resistor REALLY small, 10 to 100 ohms, to get a decent response time.

Thanks for the info!!

@GMod(Errol)

If I did the math correctly then a 10k resistor and a 100nf resistor filters the same as a 21 ohm resistor and a 47uf capacitor. The problem is that the 21 ohm resistor will draw 157mA when the switch is closed, which is a problem.

Do you have a good link explaining the maths behind this?

[Architect]

@mhectorgato

Do you have a good link explaining the maths behind this?

Ohm’s Law

Ohms Law Calculator

[Mike]

@ Architect -

I believe he is asking about RC timing calculations.

http://www.bowdenshobbycircuits.info/rc.htm

[mhectorgato]

@Mike

@ Architect -

I believe he is asking about RC timing calculations.

bowdenshobbycircuits.info

Correct

Thanks Architect & Mike!

[Architect]

Never hurts to have handy Ohm’s Law calculator close

[GMod_Errol]

Wikipedia also has a big writeup

RC circuit

BTW, the time constant is R * C.

[Unknown]

So we’re basically building it like shown in the drawing?

EDIT: Oops, changed the diagram to have the cap in parallel

[GMod_Errol]

Not quite. Will do drawing now…

[GMod_Errol]

This must be repeated for every switch…

[Unknown]

@ Errol, what does a 100nF cap look like? I’m at a loss; it’s been a very long time

[Mike_Bagnaschi]

@ kurtnelle - From the picture you got some caps and diodes. But the cap you are looking for should say 104 on it. I would say the ones you have on the right side in the picture.

[Unknown]

I’ve found 2 thanks Michael (I also found the packaging there were in) This means I only have 2. I have 103s though.

[Mike_Bagnaschi]

Those are 10nF