Power

Hi

My Uno with ethernet shield is running fine with it connected to my PC with USB cable. But then I connect the Arduino to a USB charger it did no connect to the network.

Can any one help?

--
Allan

Voltage? How connected? What is connected?

I used the USB cable and first an iphone charger 5V 0.5A, and then that does not work I tried an ipad charger 5V 2A. That still does not work. It seems that the unit power up, but the light for the ethernet connection does not light up.

If yoy connect 5V through the jack_barrel, or Vin, voltage will be to low.
Connect direct to the 5V-rail

I have now tried with 9v 300mA and 12v 1A in the jack, with same result.

allankok:
I used the USB cable and first an iphone charger 5V 0.5A, and then that does not work I tried an ipad charger 5V 2A. That still does not work. It seems that the unit power up, but the light for the ethernet connection does not light up.

With the 9V 300mA DC jack supply, or the 12V 1A DC jack supply, try them again. And see what happens if you press the reset button.

Hi, now it´s working. I only set the 12v adapter, and reset, but now the become a lit hot, so I changed to the 9v adapter. That adapter can change voltage, so I changed it to 6v and it’s still running.

Allan

The adjustable wall-wart adapters (I assume that's what it is?) are typically not trustworthy - they are normally not regulated, and you can't trust the voltage coming out of them. If it's actually putting out 6v, though, you're running the Arduino board at a voltage other than 5v - the dropout on the regulator is like 1.5-1.8v... so you've got like 4~4.5v on it. A guy on another forum trashed a pair of STM32-based boards with one of those set to 5v.

Powering with 5v through the USB connector is my recommended way of powering externally off 5v. That way, you aren't using the regulator, so you only need 5v, not 7 - and by using the USB socket, you prevent yourself from connecting it to computer at the same time like could happen if you used the 5v pin to supply it (powering from 5v pin while plugged into USB can damage the 16u2 on official Unos). That absolutely should work, if it works on USB without you having to tell it to do stuff over serial. I think there was some other issue that was preventing it from working correctly before (since I see that you reported it not working with the 12v supply, and then later it was working), so I would retry the USB charger.

is there a diode protection circuit that you can make to protect your computer from smoking, reason being you forget your stm chip is 5volt powered and you accidentally plug in your usb cable ?