I too have a brand new Grove I2C motor controller and have been struggling to get all the info required to make is fully usefull.
I have it mostly working, here are the things I had to do and some hopefully usefull info:
- Make sure power is connected to the motor controller when RUNNING your code, otherwise the I2C bus hangs/blocks" Arduino code execution. You mention LEDs on, so this is not the issue that you have.
- Did you try the delay mentioned in the wiki "arduino-0019 and it works fine, but when i use arduino - 0022, I need to add some delay() at the end of Wire.endTransmission(). "
- I am using the Arduino GUI 1.0 version and new wire lib version and had to make small changes to get the code to compile & REMOVE some lines
- The GRoveR project at erroraccessdenied.com/grover has more information, including the argument to stop the motor.
- In my first tests, one motor did not work, but there was a buzzing sound (less than 100Hz I think). This was probably buzzing at the PWM frequency (whatever that is). The motor worked and buzzing stopped, when I increased the speed argument to max 255. So it seemed that the original set speed (125) was to low to get that motor moving! But it only moves (the steering) when the wheels do not touch the floor!
- I am currently looking at the small battery pack (looks like AA batteries under the plastic) to monitor the battery voltage and noise so see if that is one area that needs an upgrade.
- I have successfully run the motor controller with it providing power to the arduino (and about 8 sensors) - but am uncertain about how this will behave with both motors running and when the batteries are low on power.
- Have you looked at jumper J4? It is used to allow the motor controller to power your arduino if it is connected (factory default), or if disconnected, you provide your own power to the Arduino - which is usually the best idea for supply stability & Arduino stability (going by other general web robot info).
labels - have not checked - just used the standard Grove cables to an I2C hub and then to the motor controller.
At least three people (including me, and I see you found it as well) are also looking for the source code and firmware (and the build info). See http://www.seeedstudio.com/forum/viewtopic.php?f=17&t=2735&hilit=i2c