Ethermega - power source vs ethernet

Combining the power of the ATmega2560 MCU with onboard Ethernet, a microSD card slot, an efficient switchmode power supply, and a small prototyping area. [Product page]
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will2be
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Ethermega - power source vs ethernet

Post by will2be » Wed Feb 24, 2016 7:44 am

I cannot find this issue in the forum. I have two EtherMega boards here and both exhibit the same behavior.

When I power the EM through USB, the ethernet works as expected.

When I power the EM through the DC jack (moving the power jumper appropriately), the ethernet does not work. The answer to Ethernet.localIP is 0.0.0.0, I get no ethernet lights when I plug-in a connection, and no net connection.

I've read in several places where the Freetronics forum monitor suggests to the forum user to supply external power to ensure that the voltage is good.

While programming the USB port powering is fine, but for deployment I want to use DC input.

I have no jumpers set on the POE header.

andrew
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Re: Ethermega - power source vs ethernet

Post by andrew » Wed Feb 24, 2016 9:30 pm

Could you please check your external DC supply - it needs to offer 7-28V DC with at least 1A current.

will2be
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Re: Ethermega - power source vs ethernet

Post by will2be » Thu Feb 25, 2016 3:27 pm

Thanks, that must be the problem. I am using an external supply to power a string of high-current LED's. They needed 5V so I have a 5V x 2A supply. I guess I will need to step up the supply and put a voltage regulator between the PS and the LED's. Other than the Wiznet the 5V supply was working fine with the EtherMega.

andrew
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Re: Ethermega - power source vs ethernet

Post by andrew » Thu Feb 25, 2016 10:05 pm

I see. The Arduino-half of the circuitry can run (not that well) at below 5V, which is what it gets after the original 5 is run through the regulator.
So yes, please increase the voltage to the board.

will2be
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Re: Ethermega - power source vs ethernet

Post by will2be » Fri Feb 26, 2016 3:28 am

I switched over to a 12VDC supply and all is good with the Wiznet.

How much current can I run through the EtherMega regulator to the 5V pin?

I need 2.5A at 5V to get through to my LED strip. If I cannot pull that through the EM regulator, then I must must get a separate regulator to pull the 12V down to 5A for the LED's.

andrew
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Re: Ethermega - power source vs ethernet

Post by andrew » Fri Feb 26, 2016 3:53 am

No more than 500 mA, the connectors on the board and PCB tracing aren't rated for 2.5A.

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