Datasheet

PIC12(L)F1501
DS41615A-page 186 Preliminary  2011 Microchip Technology Inc.
23.2 FIXED DUTY CYCLE (FDC) MODE
In Fixed Duty Cycle (FDC) mode, every time the
accumulator overflows, the output is toggled. This
provides a 50% duty cycle, provided that the increment
value remains constant. For more information, see
Figure 23-2.
The FDC mode is selected by clearing the NxPFM bit
in the NCOxCON register.
23.3 PULSE FREQUENCY (PF) MODE
In Pulse Frequency (PF) mode, every time the accumu-
lator overflows, the output becomes active for one or
more clock periods. Once the clock period expires, the
output returns to an inactive state. This provides a
pulsed output.
The output becomes active on the rising clock edge
immediately following the overflow event. For more
information, see Figure 23-2.
The value of the active and inactive states depends on
the polarity bit, NxPOL in the NCOxCON register.
The PF mode is selected by setting the NxPFM bit in
the NCOxCON register.
23.3.1 OUTPUT PULSE WIDTH CONTROL
When operating in PF mode, the active state of the out-
put can vary in width by multiple clock periods. Various
pulse widths are selected with the NxPWS<2:0> bits in
the NCOxCLK register.
When the selected pulse width is greater than the
accumulator overflow time frame, the output of the
NCOx operation is indeterminate.
23.4 OUTPUT POLARITY CONTROL
The last stage in the NCOx module is the output polar-
ity. The NxPOL bit in the NCOxCON register selects the
output polarity. Changing the polarity while the inter-
rupts are enabled will cause an interrupt for the result-
ing output transition.
The NCOx output can be used internally by source
code or other peripherals. Accomplish this by reading
the NxOUT (read-only) bit of the NCOxCON register.