Making a Smart Watch

Michael Torrie torriem at gmail.com
Wed Feb 13 17:23:45 MST 2013


On 02/13/2013 04:58 PM, Sasha Pachev wrote:
> What are my options, what are the steps I need to take, and what kind
> of price tag am I looking at? My expertise is in software, my EE
> geekiness ends with some very basic understanding of circuit
> components. I am willing to learn, though, and I am also willing to
> outsource given there is a good bang for the buck.

So microcontrollers these days don't require very much EE knowledge at
all.  If you can learn ohms law, a voltage divider, pull-up or pull-down
signalling, how to use a transister to switch a different voltage (I
always have to look up NPN vs PNP and get wiring diagrams off of google
to refresh my mind every few days), you can pretty much do anything with
embedded electronics these days.

Any Arm-based system is going to be a bit tricky because it's 3.3v
(lower volts and amps than a standard TTL-level system), and uses GPIO
pins instead of AtMega-style banks of I/O pins that have built-in
pull-ups, analog and PWM modes, and other goodies, but the principles
are still the same.

Your first stage is probably going to be using an ARM kit (say the
beaglebone or even a raspberry pi) a breadboard, and a screen.  Once you
have the UI worked out (buttons, screen, etc) using buttons on the GPIO
pins, then you can get someone to make you a board design that
integrates everything.  The cool thing about embedded arm and linux is
that you can do the programming in any language that can access the gpio
pins, which are usually accessed using special files in /proc or /sys.
So you can use python or even bash!

https://projects.drogon.net/raspberry-pi/gpio-examples/ladder-game/
http://www.emsystech.de/lcd-display-add-on-for-raspberry-pi/

But really, embedded stuff like this is now a software problem more than
an electronic issue.  I'm building a fairly complicated rate controller
with arduino right now and the electronics is really just the sensors,
and a few resistors.  I'll be using a few ancillary chips in this case
as well to RS-485 serial communication.  But the chips are fairly
self-contained these days.  Even my motor-control chip has built in
diodes so I can hook this motor (1 amp only) directly to the chip's
pins.  90% of my project is software.  And there are great communities
out there too that surround the different systems.


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