|May 10, 2011, 12:46 PM|
How to make a ITG3205 breakout from WM+ with ITG3205
It seems that a lot of people using Wii Motion+ with blue board with ITG3205, so that info and a picture might be useful to some of you.
I used the photo taken from this post (not sure who's the owner, I can't read German):
and also was inspired by this post to follow those traces on the board:
I guess picture should be pretty much self explanatory.
Just connect four wires to whatever places you prefer, I think golden pads on the back side are the most convenient place for I2C wires (SCL to X2, and SDA to X3), and pins 1 for +3.3V and 6-7 for GND. You can also connect INT to X4 if you intend to use interrupts.
I2C adress of ITG3205 is set to 0x68 (AD0 PIN connected to GND).
All you need to do to isolate ITG3205 from the other chip is to take proper tools and desolder and lift three legs (2, 3, and 4, which are connected accordingly to SCL, SDA, and INT), or just brutally cut or tear out those three legs if you never plan to use WM+ as it was intended.
Don't forget to power the board from +3.3V, and not 5V, otherwise you might get very strange readings.
I connected the SCL and SDA directly to Arduino I2C pins and just disabled AVR built-in pull-ups, no level converter needed, gyro works just fine.
UPDATE (08/25/2011): Since my brief description in the post seems to be confusing sometimes, I'll try to summarize all the needed changes here:
- you have to connect SCL to X2, SDA to X3 (or you can use other spots on the other side that are shown on the picture in yellow and green color);
- you also need to connect +3.3V and GND to the appropriate spots on the board (shown on the picture with red and black color);
- you have to disconnect the other big chip from ITG3205 by desoldering or cutting pins 2 and 3 (shown on the right picture with yellow and green small circles);
- you have to power the board with the voltage in the range from +1.8V to +3.6V; do not power it with +5V, it won't work;
- I2C adress of ITG3205 is 0x68 (7-bit), or 0xD0 (8-bit), it is the default in Alex's MultiWii code, no need to change it;
- you need to disable Arduino I2C internal pull ups (comment out #define INTERNAL_I2C_PULLUPS line), since WM+ board has it's own pull-up resistors connected to +3.3V; otherwise Arduino internal pull ups connected to +5V will mess I2C bus.
After doing that mod you cannot connect Nunchuk to that board in passthru mode anymore.
If you want to use Nunchuk in standalone mode you have to connect it in parallel to the same Arduino I2C lines (SCL and SDA).
|Jun 02, 2011, 10:11 AM|
|Jul 20, 2011, 06:45 AM|
Joined Jul 2011
Thank you! It helped me too!
But i couldn't connect nunchak correctly to such board! I think the problem is I2C address. Which contact must be connected to GND when using with nunchak?
|Jul 20, 2011, 09:38 PM|
Remember that with this mod you have to connect both boards in parallel to the same I2C pins of Arduino board.
|Jul 24, 2011, 12:23 PM|
I write for the second time because it is you who has spoken so far of this and what wmp nk blue. Correct me if I'm wrong. The wmp and nk and arduino must all be supplied with v 3.3?! how can I do from my issuing the BEC 6V. According to what I understand, my BEC powers the Arduino which in turn feeds the nk, which feeds the wmp but not by 3.3 v 5.5 v terminal, is that correct? I ask this because I want to be well on it's the only change you made to make it work. a small pattern would be welcome to allow me to see what to do because I'm not accustomed to soldering and electronic cards.
|Jul 24, 2011, 01:35 PM|
Boulybooly, unfortunately you cannot power those sensors from your BEC that outputs 6V, you will destroy them.
Arduino Pro Mini is fine if you connect 6V to it's RAW pin, it has internal 5V regulator, but WMP and NK require +3.3V power source, so you have to get a separate voltage regulator, they are cheap, here is the example of 3.3V regulator from Sparkfun.
Also looking at your pictures looks like connections are wrong. If you trying to connect ITG3205 as I described in my post then you cannot connect Nunchuk to it like you did, you have to connect them in parallel.
Only if you use unmodified WMP then you can connect Nunchuk to it in passthru mode. Here in berkely's blog on a second diagram you can see how you need to connect unmodified WMP and NK. Remember that you still have to power that blue WMP board from additional 3.3V power source.
My advice would be not to connect Nunchuk at this point at all, and make your copter work with just a Motion+. After that is working you can try to add a Nunchuk to it.
|Oct 28, 2011, 04:16 PM|
Joined Sep 2008
Can I have a traduction for noobs of this:
you need to disable Arduino I2C internal pull ups (comment out #define INTERNAL_I2C_PULLUPS line), since WM+ board has it's own pull-up resistors connected to +3.3V; otherwise Arduino internal pull ups connected to +5V will mess I2C bus
Do you know an easy explanation for the pull-up resistors ?
Why we do not need logic level convertor for SDA and SDO ?
|Oct 28, 2011, 10:42 PM|
We do not need logic converter because Arduino processor (which is ATmega328P) being powered from +5V has input high level voltage (logical 1) from +3V to +5V, so high level from WM+ at +3.3V would be still in that range, so processor will recognize it perfectly.
And input low level voltage (logical 0) should be from -0.5V to +1.5V, and low level from WM+ is usually around 0V, so again it's still within range.
There are some sensors that can be powered with as low as +1.8V, then for such sensors for sure you would need to use logic level converter.
I hope that answers your question.
If you interested in more details here is a good article about logic level thresholds.
|Dec 07, 2011, 10:10 AM|
USA, CA, Fontana
Joined Mar 2005
Thanks for the guide. Was looking for this.
The only thing that I have not done is lift the 3 pins of the other IC.
I have wired 4 line to the SOIC8 pads. Powered the little guy with 3.3V. But all I get was a little blimp of ready at the beginning of the cycle then it gone. Think removing those pins is going to help. Once that is working. I will try connecting my nunchuck.
|Dec 07, 2011, 11:16 PM|
Sure, you're welcome!
I guess that other chip probably is blocking the I2C lines, so you can either lift the legs, or just cut the traces near those legs (2 and 3) that are shown with green and yellow color.
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