[Dprglist] Rayo Pinky-Pie 7.0

Eric Yundt eric at facetcorp.com
Tue Aug 7 00:24:24 PDT 2018


Progress!  Last night we had a chance to neatly mount some stuff.  We're
using a pair of "TT" gear motors and one of the common "Smart Car" acrylic
bases on which to mount things -- so far:

    Arduino UNO
    2 x 7.4v LiPo 1000mAh (1 direct for UNO & Sensors, 1 via DC-DC
converter for motors)
    2 x 6v "TT" gear motors 1:48
    2 x 20 slot shaft encoders
    2 x Waveshare foto interrupters
    DFRobot 25W Step-down DC-DC converter (for 7.4v LiPo to 6v for motors)
    Hitec HS-422 servo motor (for sweeping sonar range finder)
    HC-SR04 ultrasonic range finder
    Pololu TB6612FNG dual H-bridge

Still to mount:

    Pololu QTR-8RC reflectance array
    TCS3200 color sensor

Finally our 1st good WOW!!! moment with the fam...  ;-)  We wired up the
foto interruptors and the sonar servo motor and I loaded up a servo sweep
program, then let'r rip!  Our foto interrupters have some nice red and
green LED's that blink with encoder disk readings.  The servo motor did
nothing but hold the sonar sensor up high and sweep back and forth, but
that made for real showy flashing lights, and moving the Robot "head"
around showed the family we actually could drive a motor with our little
Robot brain.  Rayo Pinky-Pie has officially been declared alive by all who
were there for our 1st real show-and-tell.  Our 7-year old remembered our
favorite 2 animals (dolphins & bats) that get around using similar sonar
echo object detection and explained how echos work to mama and grandma both.

I got a chance to troubleshoot and overcome our 1st real challenge --
program upload errors.  Of course we never hit this when playing with the
Arduino and a few things on a breadboard.  Finally I narrowed it down to
the shaft encoder signals interfering with the USB Tx/Rx.  We've got them
hooked to D0 & D1 of the Arduino for the external interrupt capability.
Those 2 pins also double as Tx/Rx pins used for the USB program loader.
When that finally clicked, we disconnected the foto interrupter signal
wires and were able to successfully upload a program to the UNO.

I think tomorrow we'll be able to wire up our DC-DC step-down converter,
the H-bridge, and put the juice to our drive motors.  Actually driving
around while waving the sonar back and forth will be our next big WOW!!!
waypoint on our journey into Robotics.

BTW, having comm errors with our Arduino was enough to scare me into buying
a spare UNO and the bigger brain (ATmega2560).  I found an in country
distributor of Arduino, Adafruit, and Sparkfun products and shockingly the
prices were not all that horrible!  Genuine UNO Rev 3 for $21.95 USD,
Generic UNO R3 with USB cable for $7.95, Generic MEGA 2560 Rev 3 for $18.95.

Time to start planning our software approach...  Yay!!!


On Sat, Aug 4, 2018 at 7:23 AM, Eric Yundt <eric at facetcorp.com> wrote:

> I stunned and amazed at how easy working with the Arduino UNO is.
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