Connect Arduino to cRIO
 

How would I go about wiring my Arduino uno to the Digital Sidecar for use as a slave through I2C?

I tried just wiring up pins A4 & A5 to the SDA ans SDL lines but that did not work...

I was reading somewhere that those two lines need pullup resistors, is this true and will this make a difference?

Thanks, Chiller!

Re: Connect Arduino to cRIO
 

Grab an NXT cable and cut it in half. Wire the SCL / SDA pins into the cable for the Clock / Data lines, respectively (pinout). Connect the NXT plug into the gray NXT-like plug on the Digital Sidecar. Huzzah!

-Danny

Re: Connect Arduino to cRIO
 

Use ground as well to give the sidecar/robot a common ground with the Arduino.

Also, in your Arduino code, you will need to set the clock speed for the I2C (Wire) library to the same as the cRIO/sidecar. Add the following line to your code, PRIOR to the wire.h include:
#define TWI_FREQ 38400L

Re: Connect Arduino to cRIO
 

Would you happen to know if I need those pullup resistors?

Re: Connect Arduino to cRIO
 

There are internal pullups on these lines in the sidecar, so you do not need to add additional pullups. Just connect the sidecar outputs directly to the Arduino A4/A5.