Go Down

Topic: Using a Normally-Closed Switch to Reset Arduino (Read 963 times) previous topic - next topic

WizenedEE

Hi, I have an arduino Uno that I would like to reset using a normally closed switch, rather than the normal normally-open one. The reason is that I want to reset the arduino when a cable is pulled (the same cable sends power and data to an external chip which must be syncronized)

The arduino has a 10k pullup resistor on the reset pin, and I believe the atmega328 also has an internal pull-up. So, I was thinking that I would have to put a stronger pull-down resistor, say, 1k, to gnd and then have a connection to Vcc going through the cable. Would this work? Are there any other possibilities?

Thank you!

Si

a 1K 'pull down' should work just fine. As 1 K and 10K in a potential divider would leave the reset pin at around half a volt, well below the 2.5 volt threshold.

It would however mean that you were burning 5mA through the resistor all the time.

A 4k7 resistor should work fine too, and that way you'd only be burning an extra 1 mA.
--
I write books about Arduino and Electronics: http://simonmonk.org

WizenedEE

How would a 1uF capacitor with one end on the reset line and the other getting pulled to ground when the switch is closed work? That's how the DTR auto-reset works.

Slightly unrelated, does it matter if it's .1uF or 1uF on the auto-reset for uploading code? Or does the speed of resetting matter?

Go Up
 


Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy