I2C hanging or something, please help!

I'm trying to connect a wii remote ir sensor to an arduino uno. I'm certain I have the connections correct (SCL to A5, SDA to A5) and when the circuit was built on a breadboard everything worked properly. However, now when I run the same sketch the program does not make it past either Wire.begin() or a call to Wire.write(). I assume it's Wire.begin(). I know this because I have a Serial.println before and after a call to PVision.init() which in turn calls Wire.begin() and then write(). PVision is the library I am using to communicate with the IR sensor.

Any ideas as to what would cause the call to Wire.begin() to stop the program?


Edit: I have also noticed that the L LED, which I believe is connected to pin 13, stays on or blinks very rapidly the entire time the program is running. Interestingly, while I "wait" for the Serial.println message after PVision.init() the L LED remains on.

Do you have propper 4.7Kohm pull-up resistors in each SDA and SCL line? Wrong slave address?

Find out exactly which call's stalling it- if it's begin, I'd check the library. If it's write, I'd look at the hardware.

This has been a slow learning process for me, too... the i2c buss is pretty low- level, and thus, fault- intolerant.

And as always, if it worked once, go back to the hardware and software that worked, then try going 'forward' one step at a time. I spent a long time wrestling with what turned out to be a bad USB cable...