The ethernet shield has a micro SD slot and uses pin 4 to select it. I have soldered a DS18B20 onto my shield and without the ethernet shield I can get temperature readings off the board.
As soon as I add the ethernet shield the temperature is read as zero.
Based on my reading (http://arduino.cc/en/Main/ArduinoEthernetShield) it seems digital pin 4 is off limits if you are using the ethernet shield.
Is there any way to change the pin the DS18B20 is using? I am guessing no, but wondered if there was a jumper or solder join I can change to resolve this?
Not the end of the world, since the temp sensing was a nice bonus, but it would be good to have it if possible.
Thanks,
Ben
Re: Accessing on-board DS18B20 (on EmonTX Shield) when using an ethernet shield
If you don't plan using the SD slot, then you might be able to work around it by putting the Ethernet Shield on top of the stack, and cutting off (or bending away) digital pin 4 leg so there's no connection. If you go that route you might need to add a pull-up resistor somewhere on the digital pin 4 on the Ethernet Shield, to prevent it floating low (or they may have done that on the shield, you'd need to check the schematic).
Re: Accessing on-board DS18B20 (on EmonTX Shield) when using an ethernet shield
Thanks dBC - but unfortunately I am going to be using one of these (http://www.freetronics.com/products/etherten#.U9me1vmSxP0) which is an integrated Arduino Uno clone + ethernet shield. I don't have it yet, but am testing with an Uno + Ethernet shield. I did read somewhere that if the SD slot is not being used I should be ok - but I can't find that link anymore, and I am definitely not able to access the DS18B20 currently.