PIC16F684
Figure 11-3 shows a simplified block diagram of PWM
operation.
11.3 Enhanced PWM Mode
The Enhanced CCP module produces up to a 10-bit
resolution PWM output and may have up to four
outputs, depending on the selected operating mode.
These outputs, designated P1A through P1D, are
multiplexed with I/O pins on PORTC. The pin
assignments are summarized in Table 11-3.
To configure I/O pins as PWM outputs, the proper PWM
mode must be selected by setting the P1M<1:0> and
CCP1M<3:0>
bits
(CCP1CON<7:6>
and
CCP1CON<3:0>, respectively). The appropriate
TRISC bits must also be set as outputs.
FIGURE 11-3:
SIMPLIFIED BLOCK DIAGRAM OF THE ENHANCED PWM MODULE
CCP1CON<5:4>
P1M<1:0>
CCP1M<3:0>
4
Duty Cycle Registers
2
CCPR1L
CCP1/P1A
RC5/CCP1/P1A
TRISC<5>
TRISC<4>
TRISC<3>
TRISC<2>
CCPR1H (Slave)
Comparator
P1B
RC4/C2OUT/P1B
RC3/AN7/P1C
Output
R
Q
Controller
P1C
(1)
TMR2
S
P1D
RC2/AN6/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.
The general relationship of the outputs in all
configurations is summarized in Figure 11-3.
11.3.1
PWM OUTPUT CONFIGURATIONS
The P1M<1:0> bits in the CCP1CON register allows
one of four configurations:
Note:
Clearing the CCP1CON register will force
the PWM output latches to their default
inactive levels. This is not the PORTC I/O
data latch.
• Single Output
• Half-bridge Output
• Full-bridge Output, Forward mode
• Full-bridge Output, Reverse mode
TABLE 11-3: PIN ASSIGNMENTS FOR VARIOUS ENHANCED CCP MODES
CCP1CON
ECCP Mode
RC5
RC4
RC3
RC2
Configuration
Compatible CCP
00xx11xx
10xx11xx
x1xx11xx
CCP1
P1A
RC4/C2OUT
P1B
RC3/AN7
RC3/AN7
P1C
RC2/AN6
RC2/AN6
P1D
Dual PWM
Quad PWM
P1A
P1B
Legend: x= Don’t care. Shaded cells indicate pin assignments not used by ECCP in a given mode.
Note 1: TRIS register values must be configured appropriately.
2: With ECCP in Dual or Quad PWM mode, the C2OUT output control of PORTC must be disabled.
DS41202C-page 78
Preliminary
2004 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
