[Dprglist] Robotics in Costa Rica

[Eric Yundt]

Thanks, Clay!

Clayton Timmons wrote:
> Welcome BAAHCK Eric!
> Always fun to get back to robotics.   Hope all is well in Costa Rica.
 Would
> love to chat and catch up.

Come on down!  jajaja.  I've got the coffee on... a nice roasted blend of
beans
from our own farm out back -- just kidding!  I do have coffee plants
growing but
they are mostly for show, we drink coffee we buy from the super in a bag.
;-)

I expect today is the big Robot day in our house.  Our parts from which we
hope
to build Rayo Pinky-Pie should have cleared customs yesterday and last night
would have hopped a truck to the base of our volcano.  I'll head on down to
pick
them up this afternoon after I get confirmation they've arrived.

So... I've never seen an Arduino before, but that seemed to be a goto brain
for
the simple robot these days.  I ordered an Arduino Uno, some "TT" gear
motors
with shaft encoders, the Pololu TB6612FNG H-bridge motor driver, a couple of
HC-SR04 tweeters, a 10-80 cm Sharp IR sensor, the TCS3200 Color Sensor from
Waveshare, the Pololu QTR-8RC reflectance array, a pair of foto
interrupters to
read the wheel encoders, an HS-422 servo, 2 7.4v LiPo battery packs and the
DFR0205 25W DC-DC converter from DFRobot.  Plus a few sets of the basics
our new Robot Lab lacks (variety packs of resistors, capacitors, hex
standoffs,
breadboard, jumpers, wire stripper, multimeter, etc.)

If we can swing it all in time, we'd like to show the Robot with these
skills:

    Line Following (QTR-8RC LED array)
    Find the Color (TCS3200 sensor)
    Avoid Obstacles / Find Door (HC-SR04 & Sharp IR sensor)
    Precision Driving (wheel encoders, odometry)

After studying the Arduino pins a bit, our current plan is to hook up
thusly:

    Arduino Uno powered directly from 7.4v LiPo via Power Jack
    Motors powered via 7.4v LiPo >> DFR0204 converter >> 6v

    Arduino Uno pins:

        A0 - Sharp IR Vo
        A1 - QTR LED 3
        A2 - QTR LED 4
        A3 - QTR LED 5
        A4 - QTR LED 6
        A5 - TB6612FNG STBY
        D0 - External Interrupt from Motor A Encoder DOUT
        D1 - External Interrupt from Motor B Encoder DOUT
        D2 - S3 Color Filter Select TCS3200
        D3 - S4 Color Filter Select TCS3200
        D4 - OUT Color Frequency TCS3200
        D5 - PWM for HS-422 Servo
        D6 - PWMA for Motor A via TB6612FNG H-bridge
        D7 - AIN1 Motor A Direction via TB6612FNG H-bridge
        D8 - AIN2 Motor A Direction via TB6612FNG H-bridge
        D9 - PWMB for Motor B via TB6612FNG H-bridge
        D10 - BIN1 Motor B Direction via TB6612FNG H-bridge
        D11 - BIN2 Motor B Direction via TB6612FNG H-bridge
        D12 - ECHO from HC-SR04
        D13 - TRIG from HC-SR04

Of course that runs us out of pins and I've only got 4 of the 8 LEDs for the
line sensor array hooked up.  We can live with that, but six would be
better!
I didn't think about ordering any sort of shift-register or pin multiplexor
stuff,
nor did I plan for using the I2C or SPI interfaces.  So I've been mulling
over
our options...  I can wire STBY on the H-bridge HIGH so it is always enabled
to free up A5 and the turn on LED pin of the TCS3200 HIGH to always have
the color sensor LED on so no need to waste a pin for those.

I've been trying to figure out if I can double-up on a pin or two to free
some
up for either more LEDs from our line sensor or to read a useful button
state.
Maybe we'll forgo using both the HC-SR04 and the Sharp IR in the same
configuration and gain a pin or two that way.  I'd like to keep everything
we
might use connected to minimize stress and error on Science Fair day, but
maybe we'll have to reconsider that and be prepared to carefully disconnect
something to connect something else.  However we are a team consisting
of a 5 year old who is a bit clumsy, a 6 year old who is most insightful and
in the end will become the creative inventor, and a 7 year old who is very
careful with his things.  I think our 7 year old could manage carefully
undoing
or redoing a jumper wire with practice...  Maybe all of this could be done
using switches on a breadboard.  Yeah, that would be safer.  Too bad I
didn't think about ordering some nice sized breadboard switches.

Already I know we will wish we had more parts, but until I see how this
flies
with customs and import tax I thought we ought to get our basic rig going
and then think about fancy.

I found the RobotShop.com to be a wonderful one-stop shopping place which
could consolidate all of our basic ingredients into a single shipment which
simplifies things with my freight forwarder and Costa Rican customs.

If anyone has any insight on our sensors or pin plan I'd love to hear it.  I
had to plan this out in theory and take a one-shot leap of faith on almost
all
of it.  Once we get rolling and the kids start playing with LEDs I'll be
happy.  ;-)

BTW, thanks to all involved with putting up such nice videos on DPRGclips.
They are inspiring and very instructive.

It looks like our mailing list doesn't handle including pics, but I'll
attach my
pin plan in case it makes it through.

Thanks again for any feedback and insight on an Arduino Uno based bot.

--
Eric
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