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Topic starter
Hi everyone,
I’m trying to connect an external momentary push button (normally open) to the Omini Zero 2 Go Rev 2.
I’ve wired it between SWITCH-GPIO4 and GND, but as soon as I plug any wire into the SWITCH pin and power the Omini, it turns on immediately—even without pressing the button.
I suspect the pin is floating and gets pulled low when something is connected.
Even with the button properly wired, the same happens.
I can hold the button for 5 seconds to power off the board, but as soon as I release it, the Omini turns back on.
I’d like to use an external button that behaves exactly like the onboard one—how can I achieve that? Do I need to configure something with pull-up/down resistors?
Thanks in advance for any help!
Posted : 02/05/2025 3:50 pm
The GPIO4 on Raspberry Pi connects to PB2 pin in ATtiny841, which is initialized with internal pull-up. However that internal pull-up may not be enough for your use case.
If your wire is rather long, adding extra pull-up to 3.3V is a good practise.
I don't think you are wiring it when the board is being powered, but I still want to remind everyone who read this: do NOT do wiring when the board is being powered.
Posted : 02/05/2025 4:14 pm
Topic starter
Thanks so much for your help!
One quick question: where should I take the 3.3V from on the Omini board?
I see 3.3V on pin 3 — is that the right place to use?
Do I need to add any resistors?
My idea was to bring 3.3V to the SWITCH pin and from there connect a wire to the external push button. Does that make sense?
Posted : 02/05/2025 4:22 pm
@jacopo_t You can not use the 3.3V pin in Raspberry Pi's GPIO header: there is no voltage when the Pi is not powered.
You can find Zero2Go Omini board's own 3.3V on the back of the board, it is one pin in that ICSP connector footprint, whith "3V3" label.
You definitely need a resistor to be placed between the SWITCH pin and that 3.3V pin. Otherwise you are shorting that 3.3V when pressing the button. A common value is 4.7K or 10K.
My idea was to bring 3.3V to the SWITCH pin and from there connect a wire to the external push button. Does that make sense?
It makes sense as long as you use pull-up resistor.
Posted : 02/05/2025 4:30 pm
Topic starter
@admin Thanks! I just tested it and I'm attaching a photo.
As soon as I connect the power, Omini immediately turns on — the LED lights up.
If I press and hold the button for 5 seconds, it seems to go off, but as soon as I release the button, it turns on again right away.
Posted : 02/05/2025 4:58 pm
@jacopo_t Have you checked the "Default State" mentioned on page 14 in the user manual?
Posted : 02/05/2025 6:09 pm
Topic starter
I’ve installed an application that currently doesn’t give me access to the terminal, so I can’t launch the Omini application.
However, I can confirm that if I don’t connect any wires to the switch ports, the board powers on and off normally.
So I believe the default configuration is correctly set.
That means the issue only occurs when using an external button connected to the switch.
However, if I absolutely need to verify the settings, I can install Raspberry OS and try to look for this information.
Posted : 02/05/2025 6:51 pm
Topic starter
Hi,
I tried connecting the Zero2Go Omini to my Raspberry Pi via GPIO. As soon as I did, the Pi shut down and now it won’t power on anymore — not even with the previous configuration where it was always on by default.
The LED on the Zero2Go is blinking, but pressing the button doesn’t power the Pi either.
Is it possible the board got damaged?
Thanks for any help.
Jacopo
Posted : 02/05/2025 9:11 pm