PIC16F631/677/685/687/689/690
The PWM outputs are multiplexed with I/O pins and are
11.4 PWM (Enhanced Mode)
designated P1A, P1B, P1C and P1D. The polarity of the
PWM pins is configurable and is selected by setting the
CCP1M bits in the CCP1CON register appropriately.
The Enhanced PWM Mode can generate a PWM signal
on up to four different output pins with up to 10-bits of
resolution. It can do this through four different PWM
Output modes:
Table 11-4 shows the pin assignments for each
Enhanced PWM mode.
• Single PWM
Figure 11-5 shows an example of a simplified block
diagram of the Enhanced PWM module.
• Half-Bridge PWM
• Full-Bridge PWM, Forward mode
• Full-Bridge PWM, Reverse mode
Note:
To prevent the generation of an
incomplete waveform when the PWM is
first enabled, the ECCP module waits until
the start of a new PWM period before
generating a PWM signal.
To select an Enhanced PWM mode, the P1M bits of the
CCP1CON register must be set appropriately.
FIGURE 11-5:
EXAMPLE SIMPLIFIED BLOCK DIAGRAM OF THE ENHANCED PWM MODE
DC1B<1:0>
P1M<1:0>
CCP1M<3:0>
4
Duty Cycle Registers
2
CCPR1L
CCP1/P1A
CCP1/P1A
P1B
TRIS
TRIS
TRIS
TRIS
CCPR1H (Slave)
Comparator
P1B
Output
Controller
R
S
Q
P1C
P1C
(1)
TMR2
P1D
P1D
Comparator
PR2
Clear Timer2,
toggle PWM pin and
latch duty cycle
PWM1CON
Note 1: The 8-bit timer TMR2 register is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler to create the 10-bit
time base.
Note 1: The TRIS register value for each PWM output must be configured appropriately.
2: Clearing the CCP1CON register will relinquish ECCP control of all PWM output pins.
3: Any pin not used by an Enhanced PWM mode is available for alternate pin functions
TABLE 11-4: EXAMPLE PIN ASSIGNMENTS FOR VARIOUS PWM ENHANCED MODES
ECCP Mode
P1M<1:0>
CCP1/P1A
P1B
P1C
P1D
Single
00
10
01
11
Yes(1)
Yes
Yes(1)
Yes
Yes(1)
No
Yes(1)
No
Half-Bridge
Full-Bridge, Forward
Full-Bridge, Reverse
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Note 1: Pulse Steering enables outputs in Single mode.
© 2007 Microchip Technology Inc.
DS41262D-page 133
MICROCHIP [ MICROCHIP ]
