Pages: [1]   Go Down
Author Topic: Ethernet Shield only working if USB is plugged in  (Read 881 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 2
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi smiley

I have a problem with the Ethernet shield.

If I connect the USB cable (via PC or standard phone USB charger) it works perfectly.

If I connect a 9V adapter there is a problem.
The power (red) led is on, but the link, 100M (orange) leds are not on.

A'm I missing something?

A'm using:
Arduino UNO (ATMEGA328P / ATMEGA8U2)
Arduino Ethernet Shield, SD shield (w5100 version)
9V, 1000mA adaptor.

Any ideas?

Sorry if this is a noob question, I'm new here smiley
Logged

Forum Administrator
Cambridge, MA
Offline Offline
Faraday Member
*****
Karma: 11
Posts: 3538
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

What if you press the reset button after plugging in the board? 

Does the Uno work by itself when it's on the external power supply (e.g. with just a blink program)?
Logged

0
Offline Offline
Tesla Member
***
Karma: 141
Posts: 9541
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

The external voltage regulation on my arduino (with an ethernet shield) never seemed to work correctly. When I connected a 9v battery to the external supply, the board voltage jumped to ~7v and with a 12v supply it went to ~8v+. The arduino survived, but the LEDs got brighter before I disconnected the external supply. Measure the voltage at the board 5v pin and see what it is.
Logged

Consider the daffodil. And while you're doing that, I'll be over here, looking through your stuff.   smiley-cool

Austin, TX
Offline Offline
Faraday Member
**
Karma: 71
Posts: 6146
Baldengineer
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

Ethernet shield by itself draws 190mA.  That's just sitting idle; with only 5V and GND connected.  Add 20mA for the Arduino and you are at a total of 210mA for the combined.

9V - 5V = 4V
4V * 210mA = 840mW

That's a pretty large amount of power for the Arduino's on-board regulator to dissipate.  It is quite possible the on-board regulator is shutting down. 
Logged

Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

Offline Offline
Newbie
*
Karma: 0
Posts: 2
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I have tried the reset button, but the problem was not fixed.

I'll will try to measure the voltage and look for a solution.

I'll write back if I find one smiley

Thanks for the replies.
Logged

Greenville, IL
Offline Offline
Edison Member
*
Karma: 15
Posts: 1330
Warning Novice on board! 0 to 1 chance of errors!
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


 It is recommended in a book I have, to use an external power supply. The book stated that USB power would not always be enough.
Logged


Austin, TX
Offline Offline
Faraday Member
**
Karma: 71
Posts: 6146
Baldengineer
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

I'll will try to measure the voltage and look for a solution.

It would be good to look at the 5V line and make sure it is actually 5V when externally powered, ethernet shield is connected, and any other hardware you are using is connected.
Logged

Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

Ft. Worth, Texas
Offline Offline
God Member
*****
Karma: 0
Posts: 591
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Just a thought, but I'm probably wrong.

1) USB spec is 500ma

2)You say the power LED is on, double check voltages as stated

3) If you have an aligator clip handy, ground arduino ground pin with a ground pin on computer case. (This is assuming hat you have a cable plugged in- USB is providing a ground, 9V is not...I don't think ethernet uses a ground, but I could be wrong)
Logged

KF5RVR

Camberley, Surrey, UK
Offline Offline
Newbie
*
Karma: 0
Posts: 7
Arduino rocks
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset


I have exactly this problem and the original topic owner didn't post their solution so I hope it's OK to reopen this thread.

Just as the OP (although with slightly older hardware) I have a Arduino Duemilanove with Arduino Ethernet shield running from a 9V 2A smoothed powersupply.

I've done all my coding with the USB cable plugged in and now I want to run it on it's the Ethernet Shield that won't connect.  The Arduino itself is staying powered fine  smiley-confuse

I've checked the 5V and 3.3V lines which are both fine.  Any ideas please?  smiley-confuse
Logged

Anaheim CA.
Offline Offline
Faraday Member
**
Karma: 46
Posts: 2883
...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Yes the key observation that I have is that the voltage was -7 volts on the 9V batt and when you plugged in the 12 v supply you measured ~8V... Where was your meter ground connected to? as I see the schematic there is no easy way for you to do that. If you reversed the battery D1 would not conduct so the -7 volt reading doesn't make sense and if your power supply was an AC output wall wart and this time the meter negative lead was at ground on the second measurement, that ~ 8V reading would be a correct voltage under load for 12 v AC in but the board wouldn't work. the reason isn't immediately clear... the dc after d1 from an ac supply would 'average' out the pulsating output of D1 and show that voltage but the regulator wouldn't work well or the board because of the 60Hz unfiltered component of the 'measured' voltage... Or you 'Bricked' the board.
which is short of connecting external power to the 5 and 3.3V sources pins (Bad Idea) nearly impossible.


Doc
Logged

--> WA7EMS <--
“The solution of every problem is another problem.” -Johann Wolfgang von Goethe
I do answer technical questions PM'd to me with whatever is in my clipboard

Pages: [1]   Go Up
Jump to: