Wii Motion Plus Line Level Signals

[Xptical]

To all,

I have an Arduino Mega 2560 and a WM+ gyro board.

+5v and GND are wired to pins 1 and 6 of the WM+ IAW the photos on this page: http://www.multiwii.com/connecting-elements

I have Pin 21 (SCL) tied to pin 2 of the WM+. This is the clocking signal?

Pin 20 (SDA) is ties to pin 5 of the WM+.

I have uploaded a copy of my config.


Nothing else is attached to my boards. No ESCs, gyros, or receivers. It is my understanding that when the code sees a good sensor, the "L" LED will blink. I get 2 blinks at power-on and then a steady LED.


I started probing with an o-scope and I can sometimes see a clock signal. When it's there, it's strong and clear. The problem is that I *rarely* see anything across the data line. I would think that there would be a constant block of bits coming from the WM+ to the Arduino.


So, do I need to attach other devices to "arm" the Arduino before it starts communicating with the WM+?

When looking at the line level signals, what's the flow direction? Is the Arduino providing the clock? The WM+?

Is the SDA bi-directional? Or should the WM+ just start spitting out positional data to the Arduino?



Since I can't see a consistent clock or data on the physical wires, is there a point on the WM+ board I can probe prior to the pin header? My board looks like the one on the following page:

http://letsmakerobots.com/node/23926



Anyway, if you can offer help, I'd be grateful.