Crazyflie brushed motors not spinning consistently during direct motor test

[vchidurala]

Crazyflie brushed motors not spinning consistently during direct motor test

Hi,

I am setting up a Crazyflie with a Raspberry Pi 4 and am seeing inconsistent behavior from the four motors. I would appreciate some help determining whether this is expected at low motor power or indicates a motor/hardware issue.

Setup

• Raspberry Pi 4
• Raspberry Pi OS Trixie
• Python 3.13 virtual environment
• cflib
• Crazyflie connected directly to the Raspberry Pi over USB (usb://0)
• Battery connected
• Loco Positioning Deck attached and detected (deck.bcLoco = 1)
• Standard small cylindrical brushed motors
• Propellers removed for all motor tests

Communication appears to be working correctly. For example, I can connect successfully using SyncCrazyflie, and battery telemetry (pm.vbat) is around 4.1–4.2 V.

Motor test

I enabled direct motor control using:

scf.cf.param.set_value("motorPowerSet.enable", "1")

and tested motorPowerSet.m1 through motorPowerSet.m4.

I initially tested each motor at:

• 3000
• 5000
• 7000
• 9000

for approximately 2 seconds at each level.

The motors did not behave consistently. M2 and M4 initially rotated, M3 mostly gave a small shake/twitch, and M1 did not rotate.

I then performed a short simultaneous test of all four motors at a power value of 5000 for 2 seconds.

Again, M1 did not move, M3 only gave a small shake, while M2 and M4 moved.

M1/M2 motor swap test

To determine whether the issue was associated with the motor or the M1 output, I powered everything off and physically swapped the M1 and M2 motors/connectors.

After swapping:

• The motor now connected at M1 runs well.
• The motor originally at M1, now connected at M2, runs but does not run as well.
• M4 runs well.
• M3 also runs, but weakly/inconsistently.

This seems to suggest that at least part of the behavior may follow the physical motor rather than the M1 output, but I would like to confirm the correct interpretation before replacing motors or doing additional tests.

Question

Is this amount of variation between brushed motors normal when using relatively low motorPowerSet values such as 3000–9000 with no propellers?

Is there a recommended Bitcraze procedure or motor power value for individually testing the four brushed motors and determining whether a motor should be replaced?

Thanks!

[ArisMorgens]

Hello @vchidurala!

From the tests you ran, I agree that the motor output on the board looks fine. The brushed motors should spin within the 3000-9000 range of motorPowerSet.

This behavior usually happens when there's no battery connected to the Crazyflie. Could you unplug the USB and check if the Crazyflie can power on properly with the battery? Also, if you have a Crazyradio around, could you connect via cfclient and run the same test?

If the battery looks fine, please record a video of the misbehaving propellers.

After that, we'll hopefully have more information to determine where the issue originates from.