BBB + Motor Cape V1.0 PWM under 1khz

Hi,

While working with a BBB + Motor cape I was playing around with the PWM signals generated by the DC motor outputs.

I noticed that the min. frequency has to be 1khz while if I insert 1001 as frequency it produces this with a good stability. Is it possible to have PWM signals with frequencies lower than 1khz?

Thanks in advance!