help testing ethernet shield

Using Arduino Networking, Protocols, and Devices
1

I just started learning Arduino and networking.

I connected an Arduino Uno to my iMac, uploaded "blink" example and got it working just working fine.

I then connected the Desloo Ethernet Shield W5100 Micro-sd Card Slot for Arduino 2009 UNO Mega 1280 2560 Duemilanove, tried to upload the "Ethernet>WebServer" example and received an error message:

Using Port : /dev/cu.usbmodem1411
Using Programmer : arduino
Overriding Baud Rate : 115200
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding

This continued to cycle to 10 attempts and then failed with the message, "Problem uploading to board."

I assumed that the ethernet shield is bad since it runs fine before connecting the shield (I have the correct board and port selected for the Arduino Uno before connecting the shield).

Is there a way I can test the shield to confirm it is bad and also to find out the specific error with it?

Please note: I am working with Arduino not just to use it to build with it but to understand circuit design and electronics building as a whole. I would also be interested in additional ideas on how to check, test , analyze the shield as a defective circuit board I am trying to understand/fix/repair.

Thanks.

2

Can you still upload the sketch without the shield connected? Or do you get that error ever since you first connected the shield even if you remove the shield?

3

I couldn't load the sketch into the Arduino even after removing the board. I had to reset (disconnect and reconnect) the uno and the ide to get it to function again (sans eth shield).

4

I had to reset (disconnect and reconnect) the uno and the ide to get it to function again (sans eth shield).

The UNO gets reset when you upload a sketch. What do you mean by resetting the IDE?

It sounds like a bad shield, it might include a fake chip. I found it on amazon for $5.80 although the main chip W5100 costs almost $4 if you take thousands of it.

5

Be aware that if you try to pull more current than the USB port will supply, the Mac will shut the port down without a notification. When this happens the device file is deleted and will not be recreated until the USB port is reset.

You can check whether the device file exists by opening Terminal and using the following command

ls /dev/cu*

Writing to the UNO, with a (cheap) Ethernet shield fitted, might be enough to tip the port shutdown.

Ideally, you would power the arduino with a separate 7.5V PSU (wall wart). At a push, you could connect a 5V regulated PSU to the UNO's 5V rail but you lose the rudimentary protection offered by the onboard Voltage regulator and should only do so when entirely confident of the potential consequences.

After a visual inspection and reading the data sheet, measuring current draw and voltage drop is the next step in hardware fault finding but you need the equipment to do it. i.e. An adjustable linear bench power supply and a couple of decent multimeters.

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