Robot Project 2021 Notes

(BBC micro:bit + Sparkfun moto:bit)

Sparkfun moto:bit Carrier Board

The moto:bit - micro:bit Carrier Board (Qwiic) uses a Qwiic interface? and offers pins for:

• six 3-pin sensors,
• two 3-pin servo motors
• two 2-pin “big” motors

and an I2C bus (as well as a Qwiic “port” and power switch)

       +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                              micro:bit CONNECTOR BUS


           ANALOG           DIGITAL
           DIGITAL            ONLY
              |                |
       +-+----+-------+ +------+------+-+
       | |            | |             | |                           SCL  ☐
    P0 • •  P1     P2 • • P8      P12 • • P14      P15 • • P16      SDA  ☐
   3V3 • • 3V3    3V3 • • 3V3     3V3 • • 3V3      VCC • • VCC      3V3  ☐
   GND • • GND    GND • • GND     GND • • GND      GND • • GND      GND  ☐

      SENSOR         SENSOR          SENSOR           SERVO         I2C BUS



        BLACK •   LEFT                           RIGHT  • RED
        RED   •   MOTOR                          MOTOR  • BLACK


   POWER IN
  INPUT RANGE
  VCC: 3 - 11V                                                  QWIIC


                  STOP                RUN
                 MOTORS              MOTORS

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Wheel Motor Assembly

• Geez! They weren’t kidding! Getting the front motor mounts over the big motors was a PITA! Ultimately, brute forcing it with my hand rather than pliers proved the most successful.
• The rear motor mounts were only slightly better.
• Mounting the assemblage to the bottom chassis, I was sure I was going to snap something in two or tear out a wire.
• The motor I’ve mounted on the right side has a black wire whose solder point looks suspect…

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Line folowing sensors

• The pins should be sticking out on the smooth side of the “bottom” mount.
• By contrast, this slipped together so easily that I worry it might be too loose, though it will undoubtedly tighten up when mounted to the chassis.
• This tutorial seems to be a thinly disguised advertisment for electrical tape…

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Chassis

• 10-year-olds my ass. This required a hell of a lot of strength to snap the chassis together without snapping.
• Don’t forget: there are eight snap points: Four at the corners and two above the wheels. I got the outer four, and didn’t notice the wheel ones until after the fact. It took forever to get those to snap into place.

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Wiring

• Motor wires may need to be flipped (black to red and vice versa).
• IMPORTANT SAFETY TIP: The instructions fail to mention that the battery pack should be rotated 90 degrees after slipping in the back so that the power cable is coming out the left side behind the wheel – or if the instructions did mention it, that tidbit wasn’t clear to me.
• God help you if you ever have to replace the batteries…

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Powering on

• Providing power causes the micro:bit to boot with an introductory “H…E…L…L…O” and then prompts you to push buttons A and then B.

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Uploading code to the micro:bit

• Connecting the micro:bit to desktop or laptop computer via USB provides sufficient power to program it. No need to waste the “eternal life” batteries, while downloading code to the micro:bit. So I would recommend keeping the moto:bit disconnected from the battery pack.
• The short MicroUSB to USB cable works better for me if I disconnect the micro:bit from the moto:bit and flip it upside down, exposing the side with all the writing, the RESET button, and the yellow LED.
• Identify your micro:bit version. There is a bit of contradictory information on the page, but it turns out, my kit contained a micro:bit v 1.5 but there’s a newer v 2.0. Disappointing… One would have expected SparkFun to send the latest and greatest.
• REALLY disappointing! The v 2.0 has a built-in microphone and speaker. The v 1.5 does not! That kind of blows my whole reason for playing with this! And it’s out of stock on SparkFun and AdaFruit. I’m back-ordering it on SparkFun.
• Speaking of latest and greatest, just to be sure, I like to know I’m using the most recent version of the firmware.
• After “upgrading” (though I think it already had the latest) my DETAILS.TXT contains: