Flavonoid — 1st Prototype
1st Flavonoid Prototype
Slating Flavonoid. This version I created for the C5 "Quest for Success" competition during ISEA 2006 (San Jose, CA). Just a rough prototype to start working through the concept. Here the device is communicating its current readings in real-time to my laptop. I devised a bit of code that simply keeps count (four bytes, two words, high and low) the current number of steps. My idea is that these figures would be automatically slated with a timestamp anytime the device is linked to the Flavonoid mothership. One idea I'm doing presently is to have that happen over Bluetooth (very easy, expensive in the context of what I think the device should cost) or USB (also easy, and cheap, but more awkward and you can't really do it easily if you configure the system to use a phone, like the N70, to automatically upload the data while on the go). I wore the device throughout the day and slated it when I got back (total steps - 0x0B87 in 8 hours and 1 minute)
So, basically its a Bluetooth-enabled pedometer.
This one was a prototype using a Basic Stamp, Bluetooth radio, and a Memsic 2125 dual-axis accelerometer. It's basically a DIY pedometer, that counts how many steps you've taken. The data is sent over the Bluetooth link if one is up. Otherwise, it stores the data in a nugget of EEPROM on the Basic Stamp.
What I was hoping to accomplish is just get a little work in creating a movement sensor in a very simple way. The prototype got me thinking about more complicated motion rather than just pedometric, for instance, the motion that might be involved when snowboarding or surfing, for instance. That kind of motion is more fluid in a way than walking, which has a predictable sort of cadence and beat.
The touch sensor is a little problematic because it may need to be carefully tuned to respond to human-body capacitance rather than the capacitance of any large object. There are some design notes on tuning the thing, but this will take time. Also, it will be easier to design for the sensor once it is in some sort of enclosure, perhaps wooden, for the aesthetics. This version uses the QT113H capacitive touch sensor. (Version 05 uses the AD7150 from Analog Devices, but I haven't fired it up yet.)
What did I learn?
It is entirely possible to build the code on both the Mac and on Windows, which is a great boon. Right now, I'm compiling on my Mac laptop and flashing the device on the PC. The Windows PC has the laptop drive mounted as a shared volume, and I use AVR Studio's AVR Programming interface, which is connected to my STK500 development board. I also have a AVR ICE MkII programmer which _should_ work from the laptop directly, although that'll take some fiddling to get going. I can leave the Flavonoid connected over USB on the laptop and just hook it up to the programmer and leave it that way, so that I can compile, flash the device, and then see the new output over USB on the Mac without having to undo any connections, move things around, etc.
I created a simple bit of code to do basic testing of the I/O, test each of the little "subsystems" (EEPROM, the real-time clock, accelerometer) individually.
The small 100mA 3.7 volt battery didn't last long enough. I replaced it with a 900mA 3.7 volt battery that's almost exactly the same footprint as the PCB.
Next Steps: send off the slightly modified board design to get fabricated. Start thinking about the firmware to support the device's purpose. Talk to someone about enclosure fabrication.
Incremental Prototyping: Testing the QT113H Proximity Sensor