Datasheet

 2011-2013 Microchip Technology Inc. DS40001609C-page 295
PIC16(L)F1508/9
26.0 COMPLEMENTARY WAVEFORM
GENERATOR (CWG) MODULE
The Complementary Waveform Generator (CWG)
produces a complementary waveform with dead-band
delay from a selection of input sources.
The CWG module has the following features:
• Selectable dead-band clock source control
• Selectable input sources
• Output enable control
• Output polarity control
• Dead-band control with independent 6-bit rising
and falling edge dead-band counters
• Auto-shutdown control with:
- Selectable shutdown sources
- Auto-restart enable
- Auto-shutdown pin override control
26.1 Fundamental Operation
The CWG generates two output waveforms from the
selected input source.
The off-to-on transition of each output can be delayed
from the on-to-off transition of the other output, thereby,
creating a time delay immediately where neither output
is driven. This is referred to as dead time and is covered
in Section 26.5 “Dead-Band Control”. A typical
operating waveform, with dead band, generated from a
single input signal is shown in Figure 26-2.
It may be necessary to guard against the possibility of
circuit faults or a feedback event arriving too late or not
at all. In this case, the active drive must be terminated
before the Fault condition causes damage. This is
referred to as auto-shutdown and is covered in
Section 26.9 “Auto-Shutdown Control”.
26.2 Clock Source
The CWG module allows the following clock sources
to be selected:
• Fosc (system clock)
• HFINTOSC (16 MHz only)
The clock sources are selected using the G1CS0 bit of
the CWGxCON0 register (Register 26-1).
26.3 Selectable Input Sources
The CWG generates the output waveforms from the
input sources in Tabl e 26-1.
The input sources are selected using the GxIS<2:0>
bits in the CWGxCON1 register (Register 26-2).
26.4 Output Control
Immediately after the CWG module is enabled, the
complementary drive is configured with both CWGxA
and CWGxB drives cleared.
26.4.1 OUTPUT ENABLES
Each CWG output pin has individual output enable
control. Output enables are selected with the GxOEA
and GxOEB bits of the CWGxCON0 register. When an
output enable control is cleared, the module asserts no
control over the pin. When an output enable is set, the
override value or active PWM waveform is applied to
the pin per the port priority selection. The output pin
enables are dependent on the module enable bit,
GxEN. When GxEN is cleared, CWG output enables
and CWG drive levels have no effect.
26.4.2 POLARITY CONTROL
The polarity of each CWG output can be selected
independently. When the output polarity bit is set, the
corresponding output is active-high. Clearing the output
polarity bit configures the corresponding output as
active-low. However, polarity does not affect the
override levels. Output polarity is selected with the
GxPOLA and GxPOLB bits of the CWGxCON0 register.
TABLE 26-1: SELECTABLE INPUT
SOURCES
Source Peripheral Signal Name
Comparator C1 C1OUT_sync
Comparator C2 C2OUT_sync
PWM1 PWM1_out
PWM2 PWM2_out
PWM3 PWM3_out
PWM4 PWM4_out
NCO1 NCO1_out
CLC1 LC1_out