Adding a switch to 32U4

Sorry for this being a total noob question…

I’ve used your Zumo For Arduino bots for years to teach an intro to programming & robotics class. Awesome product! They eventually wore out, so I’ve bought several of the 32U4 bots.

The kids can be rough on the bots, so I’m designing a cool-looking “cover” to protect the components & provide a handle for catching runaways. One of the things that frequently wore out on the old bots was the push button – it got a ton of use.

What I’d like to do is cover the existing buttons on the board and put a “disposable” button on my cover. I plan to solder some header pins to the top expansion holes for quick connect/disconnect of the button.

My question is this:
Your pinout says that Button A is on Arduino pin 14. To get my disposable button to work, do I connect to pin 14 & ground, or pin 14 & 5V?



Just to be clear you are asking about adding buttons to the Zumo 32U4, not the Zumo Shield for Arduino, correct?

Either way, it it is always good to check the schematic before making a modification to either of these boards. We provide them on the product pages under the resources tab. Here is a link to the schematic for the Zumo 32U4.

If you want to add another Button A on the Zumo 32U4 that functions just like the button surface-mount button, then you can connect one side of the new button to pin 14 and the other side to GND through a 1kΩ resistor, just like the button shown in the schematic. (The resistor helps protect the pin from being shorted to GND if it is accidentally set to an output and the button is pressed.) However, the circuits for Button B and Button C are a little more complicated, so let me know if you want to try adding buttons for those.

By the way, I would be interested to know more about how the buttons are failing. Are these failures occurring with the Zumo shields, the 32U4 control boards, or both? If there is some kind of visible damage, could you post pictures showing it?

- Patrick

Correct, I am targeting the Zumo 32U4.

I will use Button A as you recommend.

The button failure was on the older Zumo Shield for Arduino. It was the user pushbutton referenced on page 10 of the Pololu Zumo Shield for Arduino User’s Guide.

We always wrote our programs to wait for that button to be pushed, play a short audible countdown, then do whatever.

The failures manifested when a kid pushed the button & nothing happened. I noticed that if you pressed the button multiple times, it would sometimes work. I removed that failing button, replaced it, and everything started working again.
When the button failed, you could notice a difference in the physical press; it seemed softer. However, there was no visible damage.

Like I said, we used the heck out of those bots, and some of the kids could get pretty rough in their excitement to get back to the sumo ring. I don’t think it was a quality failure, just age & use.

Thanks for your help!

Thank you for the extra information, Jon. I am not sure if it would help much, and it may make the buttons harder to press, but you could also consider trying out this shell cover someone designed for our Zumo 32U4, or something else like it.

- Patrick