I want to use a USB connection to send data (keystrokes) through an Arduino UNO R4 WiFi to wake a sleeping computer, but power it through the barrel jack to avoid drawing power from the computer. The Arduino communicates with my main computer through a WiFiS3 script by acting as a server which continually listens for clients.
How can I transfer data from my UNO R4 WiFi without powering it from the USB? I understand it may draw some power when sending the data, but I want it to not draw any power otherwise.
Can I stop the USB from powering the board while still transferring data?
I am new to this forum, please tell me if this is placed in the wrong category, or if I should formulate my question and problem better.
I'm not sure if what you want is possible without physically modifying the UNO board. If you want to do so, you could remove D2 from the board, which is the diode that feeds into the UNO's 5V net from VUSB. This will prevent a connected USB host from powering the Arduino, while still maintaining a common GND as well as data pin connections.
Yes, that should still work as long as the Arduino is powered.
A possible undesirable side effect is if the Arduino is not powered, it may try to 'power itself' through the USB data lines. I suspect the Renesas controller on the Arduino is protected against this, but I'd have to look into it.
Btw, in all honesty, this approach to remotely powering up the computer sounds like a bit of a kludge to me. I'd be more inclined to use a more official route like Wake-on-LAN using a WiFi to ethernet gateway/router.