W5100 + Mega 2560 prevents uploading sketch

Projects Networking, Protocols, and Devices
1

I am trying to iron-out some problems with my Arduino Mega 2560 and a W5100 break-out board (this one).

Connecting the W5100's reset line to Arduino RST means it resets properly with the Arduino.

However doing so prevents uploading code successfully. (It hangs on "uploading" then I get: avrdude: stk500v2_getsync(): timeout communicating with programmer)

I can solve this either by disconnecting the W5100 reset pin whilst uploading code, then reconnecting it when done, then hitting reset on the Arduino once again. Or I can simply tie W5100 reset high, but that means W5100 chip isn't reset.

When I take my project to PCB, right now the only option is for me to have a physical switch that deals with this, but I'd really rather not!

I've checked some posts on this issue but most seem related to people using a stackable shield.

I also experimented with connecting the W5100 reset pin to an IO pin on the mega and faffing with a setup routine that ties it high for a second, then low then high to reset the card. I couldn't make that work.

Any other ideas?

2

If there is a capacitor on the reset line on the w5100 board, that could cause the problem you describe. It will prevent the reset line from going low enough to reset the Arduino and the breakout board.

Here is a test. Connect the w5100 board reset line to the reset on the Arduino, then when you want to upload a new sketch, press the reset button on the Arduino while the sketch compiles, then release it when the IDE shows "uploading". Does it upload the sketch?

3

@SurferTim

Thanks. When I do exactly what you described, it still hangs on "uploading". I experimented with holding Arduino reset button for a bit longer after the "uploading" appears as well, but to no avail.

4

Then it is not the same problem that the shields have. Only other thing I can advise is check the w5100 IC for solder bridges.