The following code generates the proper frequency provided I specify 980 or higher.

If I specify 976 the PWM frequency suddenly divides by 4 to 244Hz.

If I specify 400, the output frequency again divides by 4 and generates 100Hz.

What gives?


Code:
DEFINE  OSC 4 
HPWM 1,127,977      '980 = 980Hz, 977 = 980Hz,  976 = 244Hz,, 400 = 100Hz