If powering the Arduino (Mega) through the USB port, is a voltage of 5.19VDC acceptable?
3 Answers
Yes, the ATMEGA328 processor will work without any problem, in fact if you go in the power informations section on the datasheet, you will find that the processor can run from a little less of 3V to a maximum of 5.5V.
Just be careful, because the processor works at that power, but the board will need from 5 to 5.5V.
That's the approximate expected voltage. The Arduino devices are typically powered at 5V, but the chips themselves are rated to work at values lower and higher than 5V.
The 5.19V you see, I guess you expect 5.00V, is a combination of power supply tolerance and the tolerance of your voltmeter.
Your voltmeter also has some error, we tend to forget that sometimes.