MA180025 Microchip Technology, MA180025 Datasheet - Page 180

• Manufacturer Part Number: MA180025
• Description: MODULE PLUG-IN PIC18F87J90 PIM
• Manufacturer: Microchip Technology
• Series: PIC®r

Specifications of MA180025

• Accessory Type: Plug-In Module (PIM) - PIC18F87J90
• Product: Microcontroller Modules
• Silicon Manufacturer: Microchip
• Core Architecture: PIC
• Core Sub-architecture: PIC18
• Silicon Core Number: PIC18F
• Silicon Family Name: PIC18FxxJxx
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: PICDEM LCD 2 Demonstration Board (DM163030)
• For Use With: DM163030 - KIT DEV PICDEM LCD2
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC18F87J90 FAMILY
16.4.2
The PWM duty cycle is specified by writing to the
CCPR2L register and to the CCP2CON<5:4> bits. Up
to 10-bit resolution is available. The CCPR2L contains
the eight MSbs and the CCP2CON<5:4> contains the
two LSbs. This 10-bit value is represented by
CCPR2L:CCP2CON<5:4>. The following equation is
used to calculate the PWM duty cycle in time:
EQUATION 16-2:
CCPR2L and CCP2CON<5:4> can be written to at any
time, but the duty cycle value is not latched into
CCPR2H until after a match between PR2 and TMR2
occurs (i.e., the period is complete). In PWM mode,
CCPR2H is a read-only register.
TABLE 16-4:
DS39933D-page 180
Timer Prescaler (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
PWM Duty Cycle = (CCPR2L:CCP2CON<5:4>) •
PWM Frequency
PWM DUTY CYCLE
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
T
OSC
• (TMR2 Prescale Value)
2.44 kHz
FFh
16
14
9.77 kHz
FFh
12
4
39.06 kHz
The CCPR2H register and a 2-bit internal latch are
used to double-buffer the PWM duty cycle. This
double-buffering is essential for glitchless PWM
operation.
When the CCPR2H and 2-bit latch match TMR2,
concatenated with an internal 2-bit Q clock or 2 bits of
the TMR2 prescaler, the CCP2 pin is cleared.
The maximum PWM resolution (bits) for a given PWM
frequency is given by the equation:
EQUATION 16-3:
Note:
FFh
10
1
PWM Resolution (max)
If the PWM duty cycle value is longer than
the PWM period, the CCP2 pin will not be
cleared.
156.25 kHz
3Fh
1
8
 2010 Microchip Technology Inc.
312.50 kHz
=
1Fh
log
-----------------------------bits
1
7
log


---------------
F
F
PWM
2  
OSC
416.67 kHz


6.58
17h
1