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Author Topic: Arduino Ethernet shield and SD card  (Read 1052 times)
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Hi there!
I'm using Arduino Mega R2 with Ethernet shield R2 for some time now, it works flawlessly.
Now I received new Arduino Mega R3 and Ethernet shield R3 and I started having some issues: the same program that works well with Mega R2 + Ether R2, would start up with error reading SD card. I checked the formatting of the (new) card (using SD Formatter, as adviced in other post), tried to use the old card and still the problem would be there. Then I tested some different setups:
(Mega + Shield)
R2 + R2
R2 + R3
R3 + R3
- I found out that the problem occurs when running with the R3 shield: I will have problem with the SD card not found only if I have no external power supply.
- If I start with USB power, there will be the SD not found error, if I plug the external power and reset the Mega, still the error will come up; If then I take the SD out and put it back again in and reset the Mega, then it will work.
- With R2 + R2 I still get a good result
Does this makes any sense to anyone?
Of course I can run the setup with external power supply, but It would be great to know what might be the issue.
Any ideas?
Thanks you guys!
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Miramar Beach, Florida
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Can you post the setup() function from your sketch? Sometimes it is the way the two devices are initialized.

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Hi there!
here goes:

void setup()
{
  Serial.begin(9600);
  pinMode(10, OUTPUT); 
  digitalWrite(10, HIGH); //so that SPI will work
  pinMode(53, OUTPUT); //so that SPI will work
  pinMode(4, OUTPUT);
  delay(100); //some time to stabilize outputs
 
  if (!SD.begin(4))
  {
    Serial.println("SD card failed or not present");.
    return;
   }
  ...
}

Thanks!
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Miramar Beach, Florida
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That part looks good. ??
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Yes, and it works perfectly with Mega R2.
Only with the other combinations I need the external power supply to make it work... hmmm smiley-confuse
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