Welp, JUST over a month, and I’ve got it pretty much completed. I have it all together, working, packaged up in it’s enclosure, and mobile. (I’ll do a proper video of it soon and post it)
Microsoft has been going around coercing manufacturers of Android devices into licensing agreements, where each Android device they ship, they must pay Microsoft some amount of money. Or else Microsoft will sick their pack of lawyers on them. Every company Microsoft has tried this tactic on so far as complied in the end, and some reports have Microsoft making more money off Android licensing deals than they do off of Windows Phone 7.
Unfortunately for us, part of the deal these companies are forced to make is a Non-Disclosure Agreement forbidding them from revealing what patents MS was actually threatening them with. Now, thanks to a brazen move by Barns & Nobel (who had previously signed a similar deal with MS), we now know what patents they are using.
Some of the patents appear to be oriented towards the Linux Kernel it’s self, while others are oriented towards specific features in Android (albeit extremely general and basic features).
The following is a list of the 10 Patents and a brief description of each one.
Testing the accuracy of my device has been quite an interesting ride, and it has lead me to one conclusion: Breathalyzers are far from an ideal way of testing Blood Alcohol Content (BAC).
This must be why in real serious cases, Police Departments use blood or urine tests as they are directly measuring the concentration of alcohol in your blood.
Breathalyzers however, are a one-off test. Quite simply, they are measuring the amount of alcohol gas in your mouth. Thats an important distinction. There is the obvious factor that could throw off the test, that you could have liquid alcohol in your mouth. Some of this will be in gas form, and thus what you will be measuring is the concentration of that liquid. Which has absolutely ZERO to do with your BAC.
It’s obvious, but let me really drive this point home: you can take a mouth full of Vodka, spit it out, even rinse your mouth, and still blow a deadly level on a Breathalyzer, mean while your BAC is still zero.
Still waiting on Arduino to release their WiFi shield… So the drinking continues! Er… I mean the MQ3 project continues!
So I’ve put some time into looking for parts and methods for more making this handheld. Ordered some bits, and I’ll update more on that once those parts come in. But the more immediate and all important challenge, is continuing to iterate on the over all implementation of the circuits and software that turn this into a Breathalyzer.
Accuracy is important if this project is going to be successful. There are limitations to the MQ3 sensor, but I want to get the most out of it. So after increasing the accuracy 4.5x last week, we tested again. (All these tests occur when my friends come over to watch The Walking Dead on Friday’s). The first test we saw values ranging between 0 to 6. (Remember these values are just voltage readings from an Analog to Digital [A2D] converter provided on the Arduino). Now that wasn’t good, over 10 beers, the values only increased 6 points. That’s not nearly enough resolution in the signal to be useful. My second attempt after the 4.5x bump in resolution, produced values between 11 and 23. (Note the oddity there of nothing below 11. In my next post I’ll go into my testing procedures, and why there are oddities in these readings, as well as almost certainly in commercial breathalyzers used by authorities.) Continue reading