Monday, July 5, 2010

I Love the Mailman

I think certain clarifications are in order - I am completely heterosexual; its just that today, one of the mailmen brought me a few parcels, which I have been eagerly waiting for. One of those parcels was a Sensiron SDP610 sample, which is a CMOS differential pressure sensor; the other parcel is the subject of this blog.

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Left: The Sensirion SDP610 differential pressure sensor
Right: A Nintendo Wii MotionPlus clone

I’m building a quadrotor, and after doing a bit of searching online, found that IMUs cost a bomb. Not wanting to spend $$$ on commercial units I decided to go the DIY way. I got onto DealExtreme and purchased a Wii MotionPlus clone (hereafter simply ‘M+’). The original M+ was made by Nintendo (of the Super Mario/Contra/Space Invaders fame), as an accessory for its Wii gaming console.

The Wii revolutionized the way the world played video games. Nintendo introduced a motion controlled gaming device that took the world by storm. However soon, gamers wanted more, and when they found that the WiiMote controller gave inaccurate results when moved vigourously, they decide to add a piggy-back module to the controller.

The M+ is a 3 axis gyroscope to complement the 3 axis accelerometer already in the WiiMote. Simple maths says 3+3=6; the M+ coupled with the WiiMote gives a complete 6DOF motion controller, using which you can 'swing’ a simulated golf club, or ‘throw’ punches at the world’s deadliest boxer, maybe even ‘play’ a game of pool.

So I spent USD12~INR550, and DX shipped me the M+ along with a complimentary rubber sleeve to protect my (inexistent) WiiMote. Shipping was free, and was done via registered mail. The package took 23 days to ship from HK to Gurgaon, India.

Packaging was good – the M+ came plastic wrapped in a product box. The outer packaging was a bubble mailer. No damage other than a few wrinkles on the box’s surface.

3Good packaging by DX 

Also included in the product box were ‘documentation’ and leaflets – they’ll go straight to the raddi pile to be sold as scrap paper since I can’t read Chinese. Thoughtful of the manufacturers, but useless to me :-|

Decent build quality

The M+ itself looks solid, and build quality is good – no loose bits or clamps (not that it really matters since I’m gonna tear it apart anyway). The M+ presented me with a small problem – it was held together by tri-wing screws. Not one to be outsmarted by two screws, I took a small flathead screwdriver and gently got the screws out.

The tri-wing and the flathead that got it out.

The pieces

Here are the innards of the M+:

The upper side of the PCB. Visible on the top left corner is the IXZ650 gyro. The black epoxy in the centre covers the microcontroller, in a CoB construction style. The connector is to the left, while the expansion port is to the flat cable on the right.

The bottom side of the PCB. In the centre is the IDG650. On the top right is what seems like an EEPROM chip.

It seems funny why the clone would have two 2-axis gyros when just a 2-axis and a 1-axis would suffice. I guess I’ll have to get my hands dirty to see if there’s any difference in its functioning.

Updates in a bit.

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