Hi all,
I'm using Arduino Nano 3.0 powered by external power supply (12V
connected to "Vin" pin).
It reads temperature values from the sensor and stores results in a flash memory.
Everything is OK.
But, sometimes, I need to connect a notebook to the USB-serial port
to validate the measuring data or change parameters on a text menu.
The problem is:
When I connect to a computer (my notebook or others), without disconnecting the
external power, it doesn't recognize the USB device.
The LEDs RX and TX on Nano board don't flash.
I have tested 3 Nano boards.
No problem if Nano is only powered over USB, but there is no USB host
device where this hardware will be placed.
No problem if Nano is powered over USB and I connect the external source too.
Conclusion: I can't use USB port just as a monitor when the board is
being powered by external power source.
The same project works fine on Arduino Duemilanove board. Why?
Another question:
How "the FTDI FT232RL chip on the Nano is only powered if the board is
being powered
over USB" if VCC and VCCIO pins are connected to +5V line? Is this +5V line
powered by voltage regulator, isn't it?