Hi,
There is plenty of reference to the 'OFF' pin on a google search, but all they say is uno-r4 wifi has one, but not how to use it.
Is power off when it is high?
Is it 5v or only 3.3v?
If I have missed this in the documentation, I think I have been through it all, please point to where it is.
Thankyou
"OFF" is connected to pin 7 of the buck converter IC.
From the ISL854102 datasheet
Connecting "OFF" to GND will turn off the +5V supply, and hence the +3V3 (unless the board is powered by USB).
The UNO R4 WiFi features a VRTC pin, that is used to keep the onboard RTC running, even when the boards power supply is is cut off. In order to use this, apply a voltage in the range of 1.6 - 3.6 V to the VRTC pin.
A real-time clock (RTC) is used to measure the time, and is useful in any time-tracking applications.
It is a shame that this feature is not available on the Uno R4 Minima as well.
Thanks for the explanation @JohnLincoln , and I can confirm this. As you stated the OFF pin will disable the board's power supply if powered via VIN. Shorting it while powered via USB will have no effect.
We will update the documentation with a note on this. Thank you!
Hi @ksoderby
Actually @JohnLincoln was responding to my post as I posted the explanation from the documentation
Hi @arduinobotting I was referring to this explanation:
Your post is also of course, accurate 
and thanks for referencing the documentation 
No worries 
Thank you @JohnLincoln for your prompt reply.
Where did you come by the detailed circuit diagram? I only saw the block diagrams on the Arduino datasheet ABX00087.
Blockquote
4hpost #3
The UNO R4 WiFi features a VRTC pin, that is used to keep the onboard RTC running, even when the boards power supply is is cut off. In order to use this, apply a voltage in the range of 1.6 - 3.6 V to the VRTC pin.
A real-time clock (RTC) is used to measure the time, and is useful in any time-tracking applications.
Blockquote
Thankyou I had read that.
The schematics are to be found at https://docs.arduino.cc/resources/schematics/ABX00087-schematics.pdf
I got there by clicking on the "schematics in .pdf" button on the webpage: https://store.arduino.cc/products/uno-r4-wifi
Thanks.
Didn't think to look at the store page!?
You will also find the schematics in the resources section of this board:
I missed that bit, didn't scroll down far enough!
A post was split to a new topic: When I unplug USB and plug back again, RTC is set to initial time
Check this Arduino UNO R4 WiFi VRTC & OFF Pins
