You are currently browsing the October, 2012 archives.

Joyous Samhain

Posted 2012.10.31 11.51 in Spiritual by Stephanie

Blessed be, everyone.

ISEB Mark III – Electronics Done!

Posted 2012.10.27 11.30 in Computers/Internet/Technology by Stephanie

I could be wrong, but I’m pretty sure that as of this morning, I’ve finished the electronics on the Integrated Sensors Electronic Bracer Mark III. (Wait haven’t I said that before?)

I’ve mounted the last electronic component. It seems to be working fine. All that remains to be done from this point, is finishing the software and the new leather bracer. And an enclosure.

The last part was the micro TV-B-Gone that I assembled a while back.

I’m pretty happy with how things have turned out, even if it has taken a few months to get to this point. It’s all self-contained and even though there are a couple wires, nothing is going to be flexing around – it’s one solid unit.

One minor challenge is the name – ISEB-6 is not entirely applicable as the Mark III has more than 6 sensors… and ISEB-8 just doesn’t roll off the tongue as well. #madscienceproblems

Tweeted 2012.10.22 3.43 in DID, Twitter by Stephanie

D’oh! A Deer!

Posted 2012.10.21 12.51 in Uncategorized by Stephanie

Filed under Things You Don’t Expect To Encounter While Walking Downtown.

Halfway around the block from my house, in a little parkette, was this doe munching quietly on some leaves.¬†She didn’t seem to mind the handful of us who stopped to watch and snap some pictures.

Remarkable.

Mark III Rev D – It’s Alive!

Posted 2012.10.21 10.40 in Computers/Internet/Technology by Stephanie

The ISEB-6 Mark III revision D is alive! I put the finishing touches on the soldering this morning. All that’s left now is finalizing the software. And making the actual leather bracer. And mounting the electronics. And building a slick enclosure. And…

Ok there’s a lot more to go yet. But still – look!

Isn’t it kewl?

The only real bother I ran into was the display’s only got 3 bolts instead of 4. It’s still sturdy, the data connections are all soldered solid. The problem was when I routed all the traces, I forgot to leave room on both sides of the board for the hardware. So the top-left corner under the screen has two SMD resistors that would short against the nut, and the bottom of the board has two traces that would be cut if I counter-sunk the hole to accomodate the flat-head bolt. Bummer.

Apart from the problem with that one bolt, everything else went together fairly smoothly. Mostly.

The image below shows it almost ready for the screen – the BMP085 is in place for sensing temperature and air pressure; the ADXL345 is in place for measuring accelleration. I’ve also added a white LED to serve as a flashlight, and with some creative snipping and soldering, I fit the Lillypad Vibration motor in underneath the screen too!

When the whole thing’s done and finished, I’ll be posting everything (code, board layout, BOM, assembly) so anyone can make their own ISEB-6.

Also noteworthy: there are still two available analog inputs (A0 and A1) and three available digital IO ports – B2, C2, and C3. Expansion possibilities!

I positioned C3 near the ICSP port so one could add a SPI peripheral by using C3 as a slave select (the display is already using the default SS pin). C2 is on the sub-board with the buttons, to allow expansion there. The other three available I/O pins, along with the I2C bus and power are available at the top edge of the board for easy expansion.

Building & Testing

Posted 2012.10.20 9.59 in Computers/Internet/Technology by Stephanie

Last night I started the build of the latest version of the ISEB-6 circuit board. So far it’s all been surface-mount parts, but I was able to get it to this point using a standard handheld soldering iron with a fine tip.

The smallest-pitch part is the FT232R chip (USB to serial) which has 28 leads that are only 3/10ths of a millimeter across, and about 3/10ths of a millimeter between each pin. That’s basically soldering with your nose to the board, the soldering iron right next to your face, and while using a 5x jeweller’s loupe to see what you’re doing.

At least, that’s my technique.

Apart from the microcontroller and the USB chip, I’ve installed & tested the GPS module, temperature sensor, humidity sensor, light sensor, a voltage-divider for monitoring the battery charge, the voltage regulator and the LiPo charger. And of course all the sundry supporting passive components, and a smattering of LEDs.

There’s only about a half dozen surface-mount parts left to be mounted. The three remaining ICs though are tricky. They don’t have leads – they have pads on the bottom, so you can’t actually get to them with a soldering iron.

To get these soldered, I need to use a hot air tool and some luck. There’s the air-pressure sensor, an accellerometer, and the magnetometer. I’ll put them down in that order (from least-complex to most, and least-expensive to most.) and test between each one to ensure they’re working. All three use I2C so it’s pretty straightforward to test if they’re working or not.

Then the last bit of work on the circuit-board is to mount the display screen. This will require a little bit of hardware work to securely mount it with the mounting holes. It has to be last since it covers some of the other circuitry.

And after that, the leather-work begins – making a new wristband, and mounting / enclosing the circuitboard.

Yummy Purple PCB

Posted 2012.10.16 21.56 in Computers/Internet/Technology by Stephanie

Another batch of boards from OSHPark has arrived.

More precision soldering in my near future.

Looking forward to it.