Fio v3 power control

Projects Networking, Protocols, and Devices
1

hi everyone,

super noob here so apologies in advance for any posting mistakes I am about to make.

I am trying to use the fio v3 (atmega32u4) to power two (5v) fans. I was hoping to connect them to the "- and 5v" holes on the back of the device so when I plug in the USB cable - they receive power. This does in fact work, but is there any way to program the Fio to give the fans power based on a switch or input of some kind? or are those spots hard wired to just output 5v no matter what if a USB cable is plugged in? See pic attached for reference.

Thank you in advance for any advice!

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2

Hardwired if you look at the board schematic.
You need to add a BJT transistor or MOSFET that can be controlled with a PWM signal for controlling fan speed.

3

thank you - so basically what the MOSFET or BJT transistor will do is reduce the voltage to such a level the fan won't run at all? how would I adjust it up or down though?

also, what about controlling the fan speed with a bluetooth interface such as an xbee on this board? or will that still not be addressing the hardware problem?