Advanced settings – Pololu Simple User Manual

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Invert motor direction option enabled, Forward means the average voltage on OUTA is less than the average voltage
on OUTB.

The PWM frequency setting specifies the frequency of the rapidly-switching (PWM) signal used to control the
speed of the motor. Several PWM Frequency options are available between 1.12 and 21.77 kHz. The default PWM
frequency is 21.77 kHz. This is an ultrasonic frequency; it is too high for humans to hear, so you won’t hear the
high-pitched whine from the motor that other motor controllers can cause. Using a lower PWM frequency will reduce
switching losses and slightly increase the power output to the motor because the duty cycle (the percentage of the time
that the H-bridge is powering the motor) can be closer to 100%. Note that a speed of 3200 is called 100 % but it does
not correspond to a duty cycle of 100 %. The correspondence between maximum duty cycle and PWM frequency is
shown in the table below.

PWM Frequency

Duty cycle when speed is 100%

21.77 kHz

96.8%

11.07 kHz

98.4%

7.42 kHz

98.9%

5.58 kHz

99.2%

4.47 kHz

99.3%

3.20 kHz

99.5%

2.04 kHz

99.7%

1.12 kHz

99.8%

Speed zero brake amount is a number between 0 and 32 that specifies how strongly to brake the motor when the
Current Speed is set to 0. This corresponds to the percentage of time that the low-side MOSFETs will be turned on
and braking the motor. The default is 32, which means full brake. This means that whenever the Current Speed gets
set to zero (because of an error or any other reason) the motor will brake as fast as possible, and it will be relatively
hard to turn the motor by hand while it is stopped. If you would prefer that your motor have a more gradual stop or
be easier to turn while it is stopped, you can set Speed zero brake amount to 0, which is almost full coast. Another
way to have gradual stops is to set a deceleration limit, which will cause the Current Speed to slowly drop to zero.

5.3. Advanced Settings

The Advanced Settings tab lets you fine-tune the details of how your Simple Motor Controller behaves.

Pololu Simple Motor Controller User's Guide

5. Configuring Your Motor Controller

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