MKR Motor Carrier Buzz On Startup

Greetings,

I have recently received a new in box Arduino Engineering Kit. At this point I have completed the preliminary chapters of the Rev.1 documentation and have now assembled the DrawBot (from Chapter 4).

I did update the firmware via the Arduino IDE for the MKR Motor Carrier and a new symptom has started happening. When I turn on the carrier board and connect to the MKR1000 via command line in Matlab. The two little dc motors with Encoders buzz/whine really loud until I instantiate them in code. Once I do they are silent until I command a speed from them.

Is there a potential for flaw in the firmware? It's almost as if a small voltage is being applied to the channels in the H Bridge until I take ownership of them in code.

Cheers,

While I have not had any experience with this hardware, it sounds like a classic case of floating inputs of those pins you use for the small DC motors.

Try a 10K pull down resistor on those pins. That is connect a 10K resistor from the pin to ground on both motor pins.

Modify your MATLAB script to initialize and set the motor speeds to 0 as soon as the connection to the MKR1000 is established:

motorA = device.MotorA;
motorA.Speed = 0;
motorB = device.MotorB;
motorB.Speed = 0;

But that means you will still get the noise during the time it takes to establish the virtual port address, and check if a down load is required.

This is the route I take normally. I just think the firmware should be changed to pull the pins some kind of way until the programmatics takes over.

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