PIC24FJ64GA705 Datasheet, PDF (174/412 Pages) –

PIC24FJ256GA705 FAMILY
FIGURE 15-1:
OUTPUT COMPARE x BLOCK DIAGRAM (16-BIT MODE)
OCTSEL<2:0>
SYNCSEL<4:0>
TRIGSTAT
TRIGMODE
OCTRIG
OCx Clock
Sources
Trigger and
Sync Sources
Clock
Select
Increment
Reset
Trigger and
Sync Logic
Match Event
Reset
OCxCON1
OCxCON2
OCxR and
DCB<1:0>
Comparator
Match Event
OCM<2:0>
OCINV
OCTRIS
FLTOUT
FLTTRIEN
FLTMD
ENFLT<2:0>
OCFLT<2:0>
DCB<1:0>
OCxTMR
Comparator
Match Event
OCx Output and
Fault Logic
OCxRS
OCx Interrupt
OCx Pin⁽¹⁾
OCFA/OCFB⁽²⁾
Note 1:
2:
The OCx outputs must be assigned to an available RPn pin before use. See Section 11.5 “Peripheral Pin
Select (PPS)” for more information.
The OCFA/OCFB Fault inputs must be assigned to an available RPn/RPIn pin before use. See Section 11.5
“Peripheral Pin Select (PPS)” for more information.
15.2 Compare Operations
In Compare mode (Figure 15-1), the output compare
module can be configured for Single-Shot or Continu-
ous mode pulse generation. It can also repeatedly
toggle an output pin on each timer event.
To set up the module for compare operations:
1. Configure the OCx output for one of the
available Peripheral Pin Select pins if available
on the OCx module you are using. Otherwise,
configure the dedicated OCx output pins.
2. Calculate the required values for the OCxR and
(for Double Compare modes) OCxRS Duty
Cycle registers:
a) Determine the instruction clock cycle time.
Take into account the frequency of the
external clock to the timer source (if one is
used) and the timer prescaler settings.
b) Calculate the time to the rising edge of the
output pulse relative to the timer start value
(0000h).
c) Calculate the time to the falling edge of the
pulse based on the desired pulse width and
the time to the rising edge of the pulse.
3. Write the rising edge value to OCxR and the
falling edge value to OCxRS.
4. Set the Timer Period register, PRy, to a value
equal to or greater than the value in OCxRS.
5. Set the OCM<2:0> bits for the appropriate
compare operation (= 0xx).
6. For Trigger mode operations, set OCTRIG to
enable Trigger mode. Set or clear TRIGMODE
to configure Trigger mode operation and
TRIGSTAT to select a hardware or software
trigger. For Synchronous mode, clear OCTRIG.
7. Set the SYNCSEL<4:0> bits to configure the
Trigger or Sync source. If free-running timer
operation is required, set the SYNCSELx bits to
‘00000’ (no Sync/Trigger source).
8. Select the time base source with the
OCTSEL<2:0> bits. If necessary, set the TON bit
for the selected timer, which enables the com-
pare time base to count. Synchronous mode
operation starts as soon as the time base is
enabled; Trigger mode operation starts after a
Trigger source event occurs.
DS30010118B-page 174
 2016 Microchip Technology Inc.