Connection lost when attempting to drive DC motor

[Horowitz]

When attempting to link a DC motor to a Raspberry Pi Pico using an external power source via an L9110S motor driver board, an issue arises where the connection is lost in MicroBlocks, both in its Standard and Pilot versions. Could this be attributed to the amount of current being drawn? I am using Mac OS Ventura 13.5.

[John Maloney]

Yes, problem sound like crawing too much current and causing the board to "brown out" (i.e. crash due to low power supply voltage).

Ideally, the L9110S would be powered by a separate power source from power supply connected to the VCC pin of the L9110S board. For example, the L9110S might be powered by a battery pack while the Raspberry Pi Pico is powered but the USB cable.

As a test, you might try disconnecting the motor. Without no load, I would not expect to see the brown out issue, even if the Pico and L9110S share the same power supply.

Let me know if using separate power supplies helps.

I'm renaming this issue to be more descriptive.

[Horowitz]

Discovered the root cause (despite not fully understanding it) and the remedy for this issue: Avoid using a USB cable longer than 30 cm and use external power when operating a DC motor through an L9110S motor driver.

[John Maloney]

Glad you found a solution! I am surprised that the USB cable length makes a difference if you are using a separate, extenal power supply for the L9110S. Perhaps there some electrical coupling due to the common ground.

In any case, glad things are now working.