Hi, I couldn't find such information, so basically I want to power some 5V peripherals from the UNO's VIN pin, while the UNO is powered from the 5V pin by a 5V regulated supply. Is it normal to do it in such way without frying something? Also, if I introduce a voltage drop from a diode ( -0.7V ) at the 5V pin, will the VIN output the same voltage as the voltage supplied to the board?
If you have a 5V regulated power supply, power everything from that supply, including the Arduino via its "5V" pin.
Ignore the Vin pin in this case. It is a power INPUT, voltage > 7V.
You can get 5V from the IOREF pin, but don't try to draw more than 300mA.
garabetov:
Hi, I couldn't find such information, so basically I want to power some 5V peripherals from the UNO's VIN pin, while the UNO is powered from the 5V pin by a 5V regulated supply.
That is nonsensical. 