Sketch Won't Upload with Ethernet Shield Attached

Using Arduino Project Guidance
1

I too am having a problem uploading sketches to my UNO with the Ethernet Shield attached. I get the message

avrdude: stk500_getsync(): not in sync: resp=0x00

If I remove the shield, it uploads every time. But as you can imagine, it slows down the development process to:

  1. unplug the USB
  2. unplug the Ethernet Shield
  3. plug in the USB
  4. upload the sketch
  5. unplug the USB
  6. line up the pins and plug in the Ethernet Shield
  7. plug in the USB
  8. test, repeat from step 1

From looking at the schematics, I don't see why the Shield should interfere with the serial upload of the sketch. The only thing that they seem to have in common is the reset. For a while I thought that it might be that the USB-to-Serial chip could not reset both boards to begin the upload. I tried manually resetting the boards, like you had to do with the early Arduinos, but I still couldn't get the sketches to upload.

What is the problem here?

2

Earlier reversions of the Ethernet shield (which by default mean the ones sold on eBay) suffer this issue. You need to bend the pins for 0 and 1 out of the way when plugging it onto the Arduino.

3

Good thought ... but didn't work.

4

Some shields sold on ebay that have PoE support built in seem to require pushing the reset button when the code starts. Search the forum for PoE to find previous post on the issue. The ebay shields I saw with the PoE had a clear disclamer about the process.

5

zoomkat:
Some shields sold on ebay that have PoE support built in seem to require pushing the reset button when the code starts. Search the forum for PoE to find previous post on the issue. The ebay shields I saw with the PoE had a clear disclamer about the process.

Manually pressing the reset button when the sketch begins loading is one of the things I tried. I didn't try it more than half a dozen times though.

6

Perhaps you have a link to the board you purchased so we will know what you actually have. The PoE issue is with a w5100 board variant.

7

The board is a POE version of the board. It was supposed to be V6 of the Ethernet Shield. I had hoped to find a reasonably price POE module to add to it but never did. I think I got it about 6 month ago from some place in NJ but I forget the name of the place now.

Does anyone know what caused of the problem with the POE boards? I didn't see anything in the schematic that I could point to.

8

Somebody below claimed to have had some type of sequence fix for programming.

https://www.google.com/search?hl=en&as_q=PoE&as_epq=&as_oq=&as_eq=&as_nlo=&as_nhi=&lr=&cr=&as_qdr=all&as_sitesearch=http%3A%2F%2Farduino.cc%2Fforum%2F&as_occt=any&safe=off&tbs=&as_filetype=&as_rights=

9

I have had some success with manually resetting the unit while uploading. I hit reset at the same time I hit the upload bottom. I then hit the reset 1-2 seconds after the "Uploading..." message appears in the status area. It works about half the time. I guess I should have suspected the reset more than I did. It appears that the unit does not reset when you start a serial terminal, this is not normal.

Usually, when you start a serial terminal, the DTR signal goes low, this reset the Arduino. However, this does not happen when the Ethernet Shield is attached. I assume it has something to do with the added capacitance added to the Shield's reset circuit use for the power on reset.

I have done so yet, but does anyone see a down side to diode isolating the reset for the two boards. I was thinking of putting a diode on the reset pin of the ICSP connector of the Ethernet Shield. This should allow both boards to be reset by pressing the reset button on the shield however the main board would not reset the shield. I would also need to bend the reset pin back so that is also disconnected.

Does anyone see a down side to this modification?

10

thanks so much for this post. i was having the same problem with a custom shield i made and this fixed it for me.

happy camper :slight_smile: